1 .. -*- coding: utf-8-with-signature -*-
3 ==========================
4 The Tahoe REST-ful Web API
5 ==========================
7 1. `Enabling the web-API port`_
8 2. `Basic Concepts: GET, PUT, DELETE, POST`_
13 4. `Slow Operations, Progress, and Cancelling`_
14 5. `Programmatic Operations`_
17 2. `Writing/Uploading a File`_
18 3. `Creating a New Directory`_
19 4. `Getting Information About a File Or Directory (as JSON)`_
20 5. `Attaching an Existing File or Directory by its read- or write-cap`_
21 6. `Adding Multiple Files or Directories to a Parent Directory at Once`_
22 7. `Unlinking a File or Directory`_
24 6. `Browser Operations: Human-Oriented Interfaces`_
26 1. `Viewing a Directory (as HTML)`_
27 2. `Viewing/Downloading a File`_
28 3. `Getting Information About a File Or Directory (as HTML)`_
29 4. `Creating a Directory`_
30 5. `Uploading a File`_
31 6. `Attaching an Existing File Or Directory (by URI)`_
32 7. `Unlinking a Child`_
33 8. `Renaming a Child`_
34 9. `Relinking ("Moving") a Child`_
35 10. `Other Utilities`_
36 11. `Debugging and Testing Features`_
38 7. `Other Useful Pages`_
39 8. `Static Files in /public_html`_
40 9. `Safety and Security Issues -- Names vs. URIs`_
41 10. `Concurrency Issues`_
42 11. `Access Blacklist`_
45 Enabling the web-API port
46 =========================
48 Every Tahoe node is capable of running a built-in HTTP server. To enable
49 this, just write a port number into the "[node]web.port" line of your node's
50 tahoe.cfg file. For example, writing "web.port = 3456" into the "[node]"
51 section of $NODEDIR/tahoe.cfg will cause the node to run a webserver on port
54 This string is actually a Twisted "strports" specification, meaning you can
55 get more control over the interface to which the server binds by supplying
56 additional arguments. For more details, see the documentation on
57 `twisted.application.strports`_.
59 Writing "tcp:3456:interface=127.0.0.1" into the web.port line does the same
60 but binds to the loopback interface, ensuring that only the programs on the
61 local host can connect. Using "ssl:3456:privateKey=mykey.pem:certKey=cert.pem"
64 This webport can be set when the node is created by passing a --webport
65 option to the 'tahoe create-node' command. By default, the node listens on
66 port 3456, on the loopback (127.0.0.1) interface.
68 .. _twisted.application.strports: https://twistedmatrix.com/documents/current/api/twisted.application.strports.html
71 Basic Concepts: GET, PUT, DELETE, POST
72 ======================================
74 As described in `docs/architecture.rst`_, each file and directory in a Tahoe
75 virtual filesystem is referenced by an identifier that combines the
76 designation of the object with the authority to do something with it (such as
77 read or modify the contents). This identifier is called a "read-cap" or
78 "write-cap", depending upon whether it enables read-only or read-write
79 access. These "caps" are also referred to as URIs (which may be confusing
80 because they are not currently RFC3986_-compliant URIs).
82 The Tahoe web-based API is "REST-ful", meaning it implements the concepts of
83 "REpresentational State Transfer": the original scheme by which the World
84 Wide Web was intended to work. Each object (file or directory) is referenced
85 by a URL that includes the read- or write- cap. HTTP methods (GET, PUT, and
86 DELETE) are used to manipulate these objects. You can think of the URL as a
87 noun, and the method as a verb.
89 In REST, the GET method is used to retrieve information about an object, or
90 to retrieve some representation of the object itself. When the object is a
91 file, the basic GET method will simply return the contents of that file.
92 Other variations (generally implemented by adding query parameters to the
93 URL) will return information about the object, such as metadata. GET
94 operations are required to have no side-effects.
96 PUT is used to upload new objects into the filesystem, or to replace an
97 existing link or the contents of a mutable file. DELETE is used to unlink
98 objects from directories. Both PUT and DELETE are required to be idempotent:
99 performing the same operation multiple times must have the same side-effects
100 as only performing it once.
102 POST is used for more complicated actions that cannot be expressed as a GET,
103 PUT, or DELETE. POST operations can be thought of as a method call: sending
104 some message to the object referenced by the URL. In Tahoe, POST is also used
105 for operations that must be triggered by an HTML form (including upload and
106 unlinking), because otherwise a regular web browser has no way to accomplish
107 these tasks. In general, everything that can be done with a PUT or DELETE can
108 also be done with a POST.
110 Tahoe's web API is designed for two different kinds of consumer. The first is
111 a program that needs to manipulate the virtual file system. Such programs are
112 expected to use the RESTful interface described above. The second is a human
113 using a standard web browser to work with the filesystem. This user is given
114 a series of HTML pages with links to download files, and forms that use POST
115 actions to upload, rename, and unlink files.
117 When an error occurs, the HTTP response code will be set to an appropriate
118 400-series code (like 404 Not Found for an unknown childname, or 400 Bad Request
119 when the parameters to a web-API operation are invalid), and the HTTP response
120 body will usually contain a few lines of explanation as to the cause of the
121 error and possible responses. Unusual exceptions may result in a 500 Internal
122 Server Error as a catch-all, with a default response body containing
123 a Nevow-generated HTML-ized representation of the Python exception stack trace
124 that caused the problem. CLI programs which want to copy the response body to
125 stderr should provide an "Accept: text/plain" header to their requests to get
126 a plain text stack trace instead. If the Accept header contains ``*/*``, or
127 ``text/*``, or text/html (or if there is no Accept header), HTML tracebacks will
130 .. _RFC3986: https://tools.ietf.org/html/rfc3986
131 .. _docs/architecture.rst: ../architecture.rst
137 Tahoe uses a variety of read- and write- caps to identify files and
138 directories. The most common of these is the "immutable file read-cap", which
139 is used for most uploaded files. These read-caps look like the following::
141 URI:CHK:ime6pvkaxuetdfah2p2f35pe54:4btz54xk3tew6nd4y2ojpxj4m6wxjqqlwnztgre6gnjgtucd5r4a:3:10:202
143 The next most common is a "directory write-cap", which provides both read and
144 write access to a directory, and look like this::
146 URI:DIR2:djrdkfawoqihigoett4g6auz6a:jx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq
148 There are also "directory read-caps", which start with "URI:DIR2-RO:", and
149 give read-only access to a directory. Finally there are also mutable file
150 read- and write- caps, which start with "URI:SSK", and give access to mutable
153 (Later versions of Tahoe will make these strings shorter, and will remove the
154 unfortunate colons, which must be escaped when these caps are embedded in
157 To refer to any Tahoe object through the web API, you simply need to combine
158 a prefix (which indicates the HTTP server to use) with the cap (which
159 indicates which object inside that server to access). Since the default Tahoe
160 webport is 3456, the most common prefix is one that will use a local node
161 listening on this port::
163 http://127.0.0.1:3456/uri/ + $CAP
165 So, to access the directory named above, the URL would be::
167 http://127.0.0.1:3456/uri/URI%3ADIR2%3Adjrdkfawoqihigoett4g6auz6a%3Ajx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq/
169 (note that the colons in the directory-cap are url-encoded into "%3A"
172 Likewise, to access the file named above, use::
174 http://127.0.0.1:3456/uri/URI%3ACHK%3Aime6pvkaxuetdfah2p2f35pe54%3A4btz54xk3tew6nd4y2ojpxj4m6wxjqqlwnztgre6gnjgtucd5r4a%3A3%3A10%3A202
176 In the rest of this document, we'll use "$DIRCAP" as shorthand for a read-cap
177 or write-cap that refers to a directory, and "$FILECAP" to abbreviate a cap
178 that refers to a file (whether mutable or immutable). So those URLs above can
181 http://127.0.0.1:3456/uri/$DIRCAP/
182 http://127.0.0.1:3456/uri/$FILECAP
184 The operation summaries below will abbreviate these further, by eliding the
185 server prefix. They will be displayed like this::
190 /cap can be used as a synonym for /uri. If interoperability with older web-API
191 servers is required, /uri should be used.
196 Tahoe directories contain named child entries, just like directories in a regular
197 local filesystem. These child entries, called "dirnodes", consist of a name,
198 metadata, a write slot, and a read slot. The write and read slots normally contain
199 a write-cap and read-cap referring to the same object, which can be either a file
200 or a subdirectory. The write slot may be empty (actually, both may be empty,
201 but that is unusual).
203 If you have a Tahoe URL that refers to a directory, and want to reference a
204 named child inside it, just append the child name to the URL. For example, if
205 our sample directory contains a file named "welcome.txt", we can refer to
208 http://127.0.0.1:3456/uri/$DIRCAP/welcome.txt
210 (or http://127.0.0.1:3456/uri/URI%3ADIR2%3Adjrdkfawoqihigoett4g6auz6a%3Ajx5mplfpwexnoqff7y5e4zjus4lidm76dcuarpct7cckorh2dpgq/welcome.txt)
212 Multiple levels of subdirectories can be handled this way::
214 http://127.0.0.1:3456/uri/$DIRCAP/tahoe-source/docs/architecture.rst
216 In this document, when we need to refer to a URL that references a file using
217 this child-of-some-directory format, we'll use the following string::
219 /uri/$DIRCAP/[SUBDIRS../]FILENAME
221 The "[SUBDIRS../]" part means that there are zero or more (optional)
222 subdirectory names in the middle of the URL. The "FILENAME" at the end means
223 that this whole URL refers to a file of some sort, rather than to a
226 When we need to refer specifically to a directory in this way, we'll write::
228 /uri/$DIRCAP/[SUBDIRS../]SUBDIR
231 Note that all components of pathnames in URLs are required to be UTF-8
232 encoded, so "resume.doc" (with an acute accent on both E's) would be accessed
235 http://127.0.0.1:3456/uri/$DIRCAP/r%C3%A9sum%C3%A9.doc
237 Also note that the filenames inside upload POST forms are interpreted using
238 whatever character set was provided in the conventional '_charset' field, and
239 defaults to UTF-8 if not otherwise specified. The JSON representation of each
240 directory contains native Unicode strings. Tahoe directories are specified to
241 contain Unicode filenames, and cannot contain binary strings that are not
242 representable as such.
244 All Tahoe operations that refer to existing files or directories must include
245 a suitable read- or write- cap in the URL: the web-API server won't add one
246 for you. If you don't know the cap, you can't access the file. This allows
247 the security properties of Tahoe caps to be extended across the web-API
251 Slow Operations, Progress, and Cancelling
252 =========================================
254 Certain operations can be expected to take a long time. The "t=deep-check",
255 described below, will recursively visit every file and directory reachable
256 from a given starting point, which can take minutes or even hours for
257 extremely large directory structures. A single long-running HTTP request is a
258 fragile thing: proxies, NAT boxes, browsers, and users may all grow impatient
259 with waiting and give up on the connection.
261 For this reason, long-running operations have an "operation handle", which
262 can be used to poll for status/progress messages while the operation
263 proceeds. This handle can also be used to cancel the operation. These handles
264 are created by the client, and passed in as a an "ophandle=" query argument
265 to the POST or PUT request which starts the operation. The following
266 operations can then be used to retrieve status:
268 ``GET /operations/$HANDLE?output=HTML (with or without t=status)``
270 ``GET /operations/$HANDLE?output=JSON (same)``
272 These two retrieve the current status of the given operation. Each operation
273 presents a different sort of information, but in general the page retrieved
276 * whether the operation is complete, or if it is still running
277 * how much of the operation is complete, and how much is left, if possible
279 Note that the final status output can be quite large: a deep-manifest of a
280 directory structure with 300k directories and 200k unique files is about
281 275MB of JSON, and might take two minutes to generate. For this reason, the
282 full status is not provided until the operation has completed.
284 The HTML form will include a meta-refresh tag, which will cause a regular
285 web browser to reload the status page about 60 seconds later. This tag will
286 be removed once the operation has completed.
288 There may be more status information available under
289 /operations/$HANDLE/$ETC : i.e., the handle forms the root of a URL space.
291 ``POST /operations/$HANDLE?t=cancel``
293 This terminates the operation, and returns an HTML page explaining what was
294 cancelled. If the operation handle has already expired (see below), this
295 POST will return a 404, which indicates that the operation is no longer
296 running (either it was completed or terminated). The response body will be
297 the same as a GET /operations/$HANDLE on this operation handle, and the
298 handle will be expired immediately afterwards.
300 The operation handle will eventually expire, to avoid consuming an unbounded
301 amount of memory. The handle's time-to-live can be reset at any time, by
302 passing a retain-for= argument (with a count of seconds) to either the
303 initial POST that starts the operation, or the subsequent GET request which
304 asks about the operation. For example, if a 'GET
305 /operations/$HANDLE?output=JSON&retain-for=600' query is performed, the
306 handle will remain active for 600 seconds (10 minutes) after the GET was
309 In addition, if the GET includes a release-after-complete=True argument, and
310 the operation has completed, the operation handle will be released
313 If a retain-for= argument is not used, the default handle lifetimes are:
315 * handles will remain valid at least until their operation finishes
316 * uncollected handles for finished operations (i.e. handles for
317 operations that have finished but for which the GET page has not been
318 accessed since completion) will remain valid for four days, or for
319 the total time consumed by the operation, whichever is greater.
320 * collected handles (i.e. the GET page has been retrieved at least once
321 since the operation completed) will remain valid for one day.
323 Many "slow" operations can begin to use unacceptable amounts of memory when
324 operating on large directory structures. The memory usage increases when the
325 ophandle is polled, as the results must be copied into a JSON string, sent
326 over the wire, then parsed by a client. So, as an alternative, many "slow"
327 operations have streaming equivalents. These equivalents do not use operation
328 handles. Instead, they emit line-oriented status results immediately. Client
329 code can cancel the operation by simply closing the HTTP connection.
332 Programmatic Operations
333 =======================
335 Now that we know how to build URLs that refer to files and directories in a
336 Tahoe virtual filesystem, what sorts of operations can we do with those URLs?
337 This section contains a catalog of GET, PUT, DELETE, and POST operations that
338 can be performed on these URLs. This set of operations are aimed at programs
339 that use HTTP to communicate with a Tahoe node. A later section describes
340 operations that are intended for web browsers.
346 ``GET /uri/$FILECAP``
348 ``GET /uri/$DIRCAP/[SUBDIRS../]FILENAME``
350 This will retrieve the contents of the given file. The HTTP response body
351 will contain the sequence of bytes that make up the file.
353 To view files in a web browser, you may want more control over the
354 Content-Type and Content-Disposition headers. Please see the next section
355 "Browser Operations", for details on how to modify these URLs for that
359 Writing/Uploading a File
360 ------------------------
362 ``PUT /uri/$FILECAP``
364 ``PUT /uri/$DIRCAP/[SUBDIRS../]FILENAME``
366 Upload a file, using the data from the HTTP request body, and add whatever
367 child links and subdirectories are necessary to make the file available at
368 the given location. Once this operation succeeds, a GET on the same URL will
369 retrieve the same contents that were just uploaded. This will create any
370 necessary intermediate subdirectories.
372 To use the /uri/$FILECAP form, $FILECAP must be a write-cap for a mutable file.
374 In the /uri/$DIRCAP/[SUBDIRS../]FILENAME form, if the target file is a
375 writeable mutable file, that file's contents will be overwritten
376 in-place. If it is a read-cap for a mutable file, an error will occur.
377 If it is an immutable file, the old file will be discarded, and a new
378 one will be put in its place. If the target file is a writable mutable
379 file, you may also specify an "offset" parameter -- a byte offset that
380 determines where in the mutable file the data from the HTTP request
381 body is placed. This operation is relatively efficient for MDMF mutable
382 files, and is relatively inefficient (but still supported) for SDMF
383 mutable files. If no offset parameter is specified, then the entire
384 file is replaced with the data from the HTTP request body. For an
385 immutable file, the "offset" parameter is not valid.
387 When creating a new file, you can control the type of file created by
388 specifying a format= argument in the query string. format=MDMF creates an
389 MDMF mutable file. format=SDMF creates an SDMF mutable file. format=CHK
390 creates an immutable file. The value of the format argument is
391 case-insensitive. If no format is specified, the newly-created file will be
392 immutable (but see below).
394 For compatibility with previous versions of Tahoe-LAFS, the web-API will
395 also accept a mutable=true argument in the query string. If mutable=true is
396 given, then the new file will be mutable, and its format will be the default
397 mutable file format, as configured by the [client]mutable.format option of
398 tahoe.cfg on the Tahoe-LAFS node hosting the webapi server. Use of
399 mutable=true is discouraged; new code should use format= instead of
400 mutable=true (unless it needs to be compatible with web-API servers older
401 than v1.9.0). If neither format= nor mutable=true are given, the
402 newly-created file will be immutable.
404 This returns the file-cap of the resulting file. If a new file was created
405 by this method, the HTTP response code (as dictated by rfc2616) will be set
406 to 201 CREATED. If an existing file was replaced or modified, the response
409 Note that the 'curl -T localfile http://127.0.0.1:3456/uri/$DIRCAP/foo.txt'
410 command can be used to invoke this operation.
414 This uploads a file, and produces a file-cap for the contents, but does not
415 attach the file into the filesystem. No directories will be modified by
416 this operation. The file-cap is returned as the body of the HTTP response.
418 This method accepts format= and mutable=true as query string arguments, and
419 interprets those arguments in the same way as the linked forms of PUT
420 described immediately above.
422 Creating a New Directory
423 ------------------------
425 ``POST /uri?t=mkdir``
429 Create a new empty directory and return its write-cap as the HTTP response
430 body. This does not make the newly created directory visible from the
431 filesystem. The "PUT" operation is provided for backwards compatibility:
432 new code should use POST.
434 This supports a format= argument in the query string. The format=
435 argument, if specified, controls the format of the directory. format=MDMF
436 indicates that the directory should be stored as an MDMF file; format=SDMF
437 indicates that the directory should be stored as an SDMF file. The value of
438 the format= argument is case-insensitive. If no format= argument is
439 given, the directory's format is determined by the default mutable file
440 format, as configured on the Tahoe-LAFS node responding to the request.
442 ``POST /uri?t=mkdir-with-children``
444 Create a new directory, populated with a set of child nodes, and return its
445 write-cap as the HTTP response body. The new directory is not attached to
446 any other directory: the returned write-cap is the only reference to it.
448 The format of the directory can be controlled with the format= argument in
449 the query string, as described above.
451 Initial children are provided as the body of the POST form (this is more
452 efficient than doing separate mkdir and set_children operations). If the
453 body is empty, the new directory will be empty. If not empty, the body will
454 be interpreted as a UTF-8 JSON-encoded dictionary of children with which the
455 new directory should be populated, using the same format as would be
456 returned in the 'children' value of the t=json GET request, described below.
457 Each dictionary key should be a child name, and each value should be a list
458 of [TYPE, PROPDICT], where PROPDICT contains "rw_uri", "ro_uri", and
459 "metadata" keys (all others are ignored). For example, the PUT request body
463 "Fran\u00e7ais": [ "filenode", {
464 "ro_uri": "URI:CHK:...",
466 "ctime": 1202777696.7564139,
467 "mtime": 1202777696.7564139,
469 "linkcrtime": 1202777696.7564139,
470 "linkmotime": 1202777696.7564139
472 "subdir": [ "dirnode", {
473 "rw_uri": "URI:DIR2:...",
474 "ro_uri": "URI:DIR2-RO:...",
476 "ctime": 1202778102.7589991,
477 "mtime": 1202778111.2160511,
479 "linkcrtime": 1202777696.7564139,
480 "linkmotime": 1202777696.7564139
484 For forward-compatibility, a mutable directory can also contain caps in
485 a format that is unknown to the web-API server. When such caps are retrieved
486 from a mutable directory in a "ro_uri" field, they will be prefixed with
487 the string "ro.", indicating that they must not be decoded without
488 checking that they are read-only. The "ro." prefix must not be stripped
489 off without performing this check. (Future versions of the web-API server
490 will perform it where necessary.)
492 If both the "rw_uri" and "ro_uri" fields are present in a given PROPDICT,
493 and the web-API server recognizes the rw_uri as a write cap, then it will
494 reset the ro_uri to the corresponding read cap and discard the original
495 contents of ro_uri (in order to ensure that the two caps correspond to the
496 same object and that the ro_uri is in fact read-only). However this may not
497 happen for caps in a format unknown to the web-API server. Therefore, when
498 writing a directory the web-API client should ensure that the contents
499 of "rw_uri" and "ro_uri" for a given PROPDICT are a consistent
500 (write cap, read cap) pair if possible. If the web-API client only has
501 one cap and does not know whether it is a write cap or read cap, then
502 it is acceptable to set "rw_uri" to that cap and omit "ro_uri". The
503 client must not put a write cap into a "ro_uri" field.
505 The metadata may have a "no-write" field. If this is set to true in the
506 metadata of a link, it will not be possible to open that link for writing
507 via the SFTP frontend; see FTP-and-SFTP.rst_ for details. Also, if the
508 "no-write" field is set to true in the metadata of a link to a mutable
509 child, it will cause the link to be diminished to read-only.
511 Note that the web-API-using client application must not provide the
512 "Content-Type: multipart/form-data" header that usually accompanies HTML
513 form submissions, since the body is not formatted this way. Doing so will
514 cause a server error as the lower-level code misparses the request body.
516 Child file names should each be expressed as a Unicode string, then used as
517 keys of the dictionary. The dictionary should then be converted into JSON,
518 and the resulting string encoded into UTF-8. This UTF-8 bytestring should
519 then be used as the POST body.
521 ``POST /uri?t=mkdir-immutable``
523 Like t=mkdir-with-children above, but the new directory will be
524 deep-immutable. This means that the directory itself is immutable, and that
525 it can only contain objects that are treated as being deep-immutable, like
526 immutable files, literal files, and deep-immutable directories.
528 For forward-compatibility, a deep-immutable directory can also contain caps
529 in a format that is unknown to the web-API server. When such caps are retrieved
530 from a deep-immutable directory in a "ro_uri" field, they will be prefixed
531 with the string "imm.", indicating that they must not be decoded without
532 checking that they are immutable. The "imm." prefix must not be stripped
533 off without performing this check. (Future versions of the web-API server
534 will perform it where necessary.)
536 The cap for each child may be given either in the "rw_uri" or "ro_uri"
537 field of the PROPDICT (not both). If a cap is given in the "rw_uri" field,
538 then the web-API server will check that it is an immutable read-cap of a
539 *known* format, and give an error if it is not. If a cap is given in the
540 "ro_uri" field, then the web-API server will still check whether known
541 caps are immutable, but for unknown caps it will simply assume that the
542 cap can be stored, as described above. Note that an attacker would be
543 able to store any cap in an immutable directory, so this check when
544 creating the directory is only to help non-malicious clients to avoid
545 accidentally giving away more authority than intended.
547 A non-empty request body is mandatory, since after the directory is created,
548 it will not be possible to add more children to it.
550 ``POST /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir``
552 ``PUT /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir``
554 Create new directories as necessary to make sure that the named target
555 ($DIRCAP/SUBDIRS../SUBDIR) is a directory. This will create additional
556 intermediate mutable directories as necessary. If the named target directory
557 already exists, this will make no changes to it.
559 If the final directory is created, it will be empty.
561 This accepts a format= argument in the query string, which controls the
562 format of the named target directory, if it does not already exist. format=
563 is interpreted in the same way as in the POST /uri?t=mkdir form. Note that
564 format= only controls the format of the named target directory;
565 intermediate directories, if created, are created based on the default
566 mutable type, as configured on the Tahoe-LAFS server responding to the
569 This operation will return an error if a blocking file is present at any of
570 the parent names, preventing the server from creating the necessary parent
571 directory; or if it would require changing an immutable directory.
573 The write-cap of the new directory will be returned as the HTTP response
576 ``POST /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir-with-children``
578 Like /uri?t=mkdir-with-children, but the final directory is created as a
579 child of an existing mutable directory. This will create additional
580 intermediate mutable directories as necessary. If the final directory is
581 created, it will be populated with initial children from the POST request
582 body, as described above.
584 This accepts a format= argument in the query string, which controls the
585 format of the target directory, if the target directory is created as part
586 of the operation. format= is interpreted in the same way as in the POST/
587 uri?t=mkdir-with-children operation. Note that format= only controls the
588 format of the named target directory; intermediate directories, if created,
589 are created using the default mutable type setting, as configured on the
590 Tahoe-LAFS server responding to the request.
592 This operation will return an error if a blocking file is present at any of
593 the parent names, preventing the server from creating the necessary parent
594 directory; or if it would require changing an immutable directory; or if
595 the immediate parent directory already has a a child named SUBDIR.
597 ``POST /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir-immutable``
599 Like /uri?t=mkdir-immutable, but the final directory is created as a child
600 of an existing mutable directory. The final directory will be deep-immutable,
601 and will be populated with the children specified as a JSON dictionary in
602 the POST request body.
604 In Tahoe 1.6 this operation creates intermediate mutable directories if
605 necessary, but that behaviour should not be relied on; see ticket #920.
607 This operation will return an error if the parent directory is immutable,
608 or already has a child named SUBDIR.
610 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=NAME``
612 Create a new empty mutable directory and attach it to the given existing
613 directory. This will create additional intermediate directories as necessary.
615 This accepts a format= argument in the query string, which controls the
616 format of the named target directory, if it does not already exist. format=
617 is interpreted in the same way as in the POST /uri?t=mkdir form. Note that
618 format= only controls the format of the named target directory;
619 intermediate directories, if created, are created based on the default
620 mutable type, as configured on the Tahoe-LAFS server responding to the
623 This operation will return an error if a blocking file is present at any of
624 the parent names, preventing the server from creating the necessary parent
625 directory, or if it would require changing any immutable directory.
627 The URL of this operation points to the parent of the bottommost new directory,
628 whereas the /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=mkdir operation above has a URL
629 that points directly to the bottommost new directory.
631 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir-with-children&name=NAME``
633 Like /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=NAME, but the new directory will
634 be populated with initial children via the POST request body. This command
635 will create additional intermediate mutable directories as necessary.
637 This accepts a format= argument in the query string, which controls the
638 format of the target directory, if the target directory is created as part
639 of the operation. format= is interpreted in the same way as in the POST/
640 uri?t=mkdir-with-children operation. Note that format= only controls the
641 format of the named target directory; intermediate directories, if created,
642 are created using the default mutable type setting, as configured on the
643 Tahoe-LAFS server responding to the request.
645 This operation will return an error if a blocking file is present at any of
646 the parent names, preventing the server from creating the necessary parent
647 directory; or if it would require changing an immutable directory; or if
648 the immediate parent directory already has a a child named NAME.
650 Note that the name= argument must be passed as a queryarg, because the POST
651 request body is used for the initial children JSON.
653 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir-immutable&name=NAME``
655 Like /uri/$DIRCAP/[SUBDIRS../]?t=mkdir-with-children&name=NAME, but the
656 final directory will be deep-immutable. The children are specified as a
657 JSON dictionary in the POST request body. Again, the name= argument must be
658 passed as a queryarg.
660 In Tahoe 1.6 this operation creates intermediate mutable directories if
661 necessary, but that behaviour should not be relied on; see ticket #920.
663 This operation will return an error if the parent directory is immutable,
664 or already has a child named NAME.
666 .. _FTP-and-SFTP.rst: FTP-and-SFTP.rst
669 Getting Information About a File Or Directory (as JSON)
670 -------------------------------------------------------
672 ``GET /uri/$FILECAP?t=json``
674 ``GET /uri/$DIRCAP?t=json``
676 ``GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=json``
678 ``GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=json``
680 This returns a machine-parseable JSON-encoded description of the given
681 object. The JSON always contains a list, and the first element of the list is
682 always a flag that indicates whether the referenced object is a file or a
683 directory. If it is a capability to a file, then the information includes
684 file size and URI, like this::
686 GET /uri/$FILECAP?t=json :
690 "verify_uri": verify_uri,
696 If it is a capability to a directory followed by a path from that directory
697 to a file, then the information also includes metadata from the link to the
698 file in the parent directory, like this::
700 GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=json
704 "verify_uri": verify_uri,
709 "ctime": 1202777696.7564139,
710 "mtime": 1202777696.7564139,
712 "linkcrtime": 1202777696.7564139,
713 "linkmotime": 1202777696.7564139
716 If it is a directory, then it includes information about the children of
717 this directory, as a mapping from child name to a set of data about the
718 child (the same data that would appear in a corresponding GET?t=json of the
719 child itself). The child entries also include metadata about each child,
720 including link-creation- and link-change- timestamps. The output looks like
723 GET /uri/$DIRCAP?t=json :
724 GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR?t=json :
727 "rw_uri": read_write_uri,
728 "ro_uri": read_only_uri,
729 "verify_uri": verify_uri,
733 "foo.txt": [ "filenode",
738 "ctime": 1202777696.7564139,
739 "mtime": 1202777696.7564139,
741 "linkcrtime": 1202777696.7564139,
742 "linkmotime": 1202777696.7564139
744 "subdir": [ "dirnode",
749 "ctime": 1202778102.7589991,
750 "mtime": 1202778111.2160511,
752 "linkcrtime": 1202777696.7564139,
753 "linkmotime": 1202777696.7564139
757 In the above example, note how 'children' is a dictionary in which the keys
758 are child names and the values depend upon whether the child is a file or a
759 directory. The value is mostly the same as the JSON representation of the
760 child object (except that directories do not recurse -- the "children"
761 entry of the child is omitted, and the directory view includes the metadata
762 that is stored on the directory edge).
764 The rw_uri field will be present in the information about a directory
765 if and only if you have read-write access to that directory. The verify_uri
766 field will be present if and only if the object has a verify-cap
767 (non-distributed LIT files do not have verify-caps).
769 If the cap is of an unknown format, then the file size and verify_uri will
772 GET /uri/$UNKNOWNCAP?t=json :
775 "ro_uri": unknown_read_uri
778 GET /uri/$DIRCAP/[SUBDIRS../]UNKNOWNCHILDNAME?t=json :
781 "rw_uri": unknown_write_uri,
782 "ro_uri": unknown_read_uri,
785 "ctime": 1202777696.7564139,
786 "mtime": 1202777696.7564139,
788 "linkcrtime": 1202777696.7564139,
789 "linkmotime": 1202777696.7564139
792 As in the case of file nodes, the metadata will only be present when the
793 capability is to a directory followed by a path. The "mutable" field is also
794 not always present; when it is absent, the mutability of the object is not
800 The value of the 'tahoe':'linkmotime' key is updated whenever a link to a
801 child is set. The value of the 'tahoe':'linkcrtime' key is updated whenever
802 a link to a child is created -- i.e. when there was not previously a link
805 Note however, that if the edge in the Tahoe filesystem points to a mutable
806 file and the contents of that mutable file is changed, then the
807 'tahoe':'linkmotime' value on that edge will *not* be updated, since the
808 edge itself wasn't updated -- only the mutable file was.
810 The timestamps are represented as a number of seconds since the UNIX epoch
811 (1970-01-01 00:00:00 UTC), with leap seconds not being counted in the long
814 In Tahoe earlier than v1.4.0, 'mtime' and 'ctime' keys were populated
815 instead of the 'tahoe':'linkmotime' and 'tahoe':'linkcrtime' keys. Starting
816 in Tahoe v1.4.0, the 'linkmotime'/'linkcrtime' keys in the 'tahoe' sub-dict
817 are populated. However, prior to Tahoe v1.7beta, a bug caused the 'tahoe'
818 sub-dict to be deleted by web-API requests in which new metadata is
819 specified, and not to be added to existing child links that lack it.
821 From Tahoe v1.7.0 onward, the 'mtime' and 'ctime' fields are no longer
822 populated or updated (see ticket #924), except by "tahoe backup" as
823 explained below. For backward compatibility, when an existing link is
824 updated and 'tahoe':'linkcrtime' is not present in the previous metadata
825 but 'ctime' is, the old value of 'ctime' is used as the new value of
826 'tahoe':'linkcrtime'.
828 The reason we added the new fields in Tahoe v1.4.0 is that there is a
829 "set_children" API (described below) which you can use to overwrite the
830 values of the 'mtime'/'ctime' pair, and this API is used by the
831 "tahoe backup" command (in Tahoe v1.3.0 and later) to set the 'mtime' and
832 'ctime' values when backing up files from a local filesystem into the
833 Tahoe filesystem. As of Tahoe v1.4.0, the set_children API cannot be used
834 to set anything under the 'tahoe' key of the metadata dict -- if you
835 include 'tahoe' keys in your 'metadata' arguments then it will silently
838 Therefore, if the 'tahoe' sub-dict is present, you can rely on the
839 'linkcrtime' and 'linkmotime' values therein to have the semantics described
840 above. (This is assuming that only official Tahoe clients have been used to
841 write those links, and that their system clocks were set to what you expected
842 -- there is nothing preventing someone from editing their Tahoe client or
843 writing their own Tahoe client which would overwrite those values however
844 they like, and there is nothing to constrain their system clock from taking
847 When an edge is created or updated by "tahoe backup", the 'mtime' and
848 'ctime' keys on that edge are set as follows:
850 * 'mtime' is set to the timestamp read from the local filesystem for the
851 "mtime" of the local file in question, which means the last time the
852 contents of that file were changed.
854 * On Windows, 'ctime' is set to the creation timestamp for the file
855 read from the local filesystem. On other platforms, 'ctime' is set to
856 the UNIX "ctime" of the local file, which means the last time that
857 either the contents or the metadata of the local file was changed.
859 There are several ways that the 'ctime' field could be confusing:
861 1. You might be confused about whether it reflects the time of the creation
862 of a link in the Tahoe filesystem (by a version of Tahoe < v1.7.0) or a
863 timestamp copied in by "tahoe backup" from a local filesystem.
865 2. You might be confused about whether it is a copy of the file creation
866 time (if "tahoe backup" was run on a Windows system) or of the last
867 contents-or-metadata change (if "tahoe backup" was run on a different
870 3. You might be confused by the fact that changing the contents of a
871 mutable file in Tahoe doesn't have any effect on any links pointing at
872 that file in any directories, although "tahoe backup" sets the link
873 'ctime'/'mtime' to reflect timestamps about the local file corresponding
874 to the Tahoe file to which the link points.
876 4. Also, quite apart from Tahoe, you might be confused about the meaning
877 of the "ctime" in UNIX local filesystems, which people sometimes think
878 means file creation time, but which actually means, in UNIX local
879 filesystems, the most recent time that the file contents or the file
880 metadata (such as owner, permission bits, extended attributes, etc.)
881 has changed. Note that although "ctime" does not mean file creation time
882 in UNIX, links created by a version of Tahoe prior to v1.7.0, and never
883 written by "tahoe backup", will have 'ctime' set to the link creation
887 Attaching an Existing File or Directory by its read- or write-cap
888 -----------------------------------------------------------------
890 ``PUT /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=uri``
892 This attaches a child object (either a file or directory) to a specified
893 location in the virtual filesystem. The child object is referenced by its
894 read- or write- cap, as provided in the HTTP request body. This will create
895 intermediate directories as necessary.
897 This is similar to a UNIX hardlink: by referencing a previously-uploaded file
898 (or previously-created directory) instead of uploading/creating a new one,
899 you can create two references to the same object.
901 The read- or write- cap of the child is provided in the body of the HTTP
902 request, and this same cap is returned in the response body.
904 The default behavior is to overwrite any existing object at the same
905 location. To prevent this (and make the operation return an error instead
906 of overwriting), add a "replace=false" argument, as "?t=uri&replace=false".
907 With replace=false, this operation will return an HTTP 409 "Conflict" error
908 if there is already an object at the given location, rather than
909 overwriting the existing object. To allow the operation to overwrite a
910 file, but return an error when trying to overwrite a directory, use
911 "replace=only-files" (this behavior is closer to the traditional UNIX "mv"
912 command). Note that "true", "t", and "1" are all synonyms for "True", and
913 "false", "f", and "0" are synonyms for "False", and the parameter is
916 Note that this operation does not take its child cap in the form of
917 separate "rw_uri" and "ro_uri" fields. Therefore, it cannot accept a
918 child cap in a format unknown to the web-API server, unless its URI
919 starts with "ro." or "imm.". This restriction is necessary because the
920 server is not able to attenuate an unknown write cap to a read cap.
921 Unknown URIs starting with "ro." or "imm.", on the other hand, are
922 assumed to represent read caps. The client should not prefix a write
923 cap with "ro." or "imm." and pass it to this operation, since that
924 would result in granting the cap's write authority to holders of the
928 Adding Multiple Files or Directories to a Parent Directory at Once
929 ------------------------------------------------------------------
931 ``POST /uri/$DIRCAP/[SUBDIRS..]?t=set_children``
933 ``POST /uri/$DIRCAP/[SUBDIRS..]?t=set-children`` (Tahoe >= v1.6)
935 This command adds multiple children to a directory in a single operation.
936 It reads the request body and interprets it as a JSON-encoded description
937 of the child names and read/write-caps that should be added.
939 The body should be a JSON-encoded dictionary, in the same format as the
940 "children" value returned by the "GET /uri/$DIRCAP?t=json" operation
941 described above. In this format, each key is a child names, and the
942 corresponding value is a tuple of (type, childinfo). "type" is ignored, and
943 "childinfo" is a dictionary that contains "rw_uri", "ro_uri", and
944 "metadata" keys. You can take the output of "GET /uri/$DIRCAP1?t=json" and
945 use it as the input to "POST /uri/$DIRCAP2?t=set_children" to make DIR2
946 look very much like DIR1 (except for any existing children of DIR2 that
947 were not overwritten, and any existing "tahoe" metadata keys as described
950 When the set_children request contains a child name that already exists in
951 the target directory, this command defaults to overwriting that child with
952 the new value (both child cap and metadata, but if the JSON data does not
953 contain a "metadata" key, the old child's metadata is preserved). The
954 command takes a boolean "overwrite=" query argument to control this
955 behavior. If you use "?t=set_children&overwrite=false", then an attempt to
956 replace an existing child will instead cause an error.
958 Any "tahoe" key in the new child's "metadata" value is ignored. Any
959 existing "tahoe" metadata is preserved. The metadata["tahoe"] value is
960 reserved for metadata generated by the tahoe node itself. The only two keys
961 currently placed here are "linkcrtime" and "linkmotime". For details, see
962 the section above entitled "Getting Information About a File Or Directory (as
963 JSON)", in the "About the metadata" subsection.
965 Note that this command was introduced with the name "set_children", which
966 uses an underscore rather than a hyphen as other multi-word command names
967 do. The variant with a hyphen is now accepted, but clients that desire
968 backward compatibility should continue to use "set_children".
971 Unlinking a File or Directory
972 -----------------------------
974 ``DELETE /uri/$DIRCAP/[SUBDIRS../]CHILDNAME``
976 This removes the given name from its parent directory. CHILDNAME is the
977 name to be removed, and $DIRCAP/SUBDIRS.. indicates the directory that will
980 Note that this does not actually delete the file or directory that the name
981 points to from the tahoe grid -- it only unlinks the named reference from
982 this directory. If there are other names in this directory or in other
983 directories that point to the resource, then it will remain accessible
984 through those paths. Even if all names pointing to this object are removed
985 from their parent directories, then someone with possession of its read-cap
986 can continue to access the object through that cap.
988 The object will only become completely unreachable once 1: there are no
989 reachable directories that reference it, and 2: nobody is holding a read-
990 or write- cap to the object. (This behavior is very similar to the way
991 hardlinks and anonymous files work in traditional UNIX filesystems).
993 This operation will not modify more than a single directory. Intermediate
994 directories which were implicitly created by PUT or POST methods will *not*
995 be automatically removed by DELETE.
997 This method returns the file- or directory- cap of the object that was just
1001 Browser Operations: Human-oriented interfaces
1002 =============================================
1004 This section describes the HTTP operations that provide support for humans
1005 running a web browser. Most of these operations use HTML forms that use POST
1006 to drive the Tahoe node. This section is intended for HTML authors who want
1007 to write web pages that contain forms and buttons which manipulate the Tahoe
1010 Note that for all POST operations, the arguments listed can be provided
1011 either as URL query arguments or as form body fields. URL query arguments are
1012 separated from the main URL by "?", and from each other by "&". For example,
1013 "POST /uri/$DIRCAP?t=upload&mutable=true". Form body fields are usually
1014 specified by using <input type="hidden"> elements. For clarity, the
1015 descriptions below display the most significant arguments as URL query args.
1018 Viewing a Directory (as HTML)
1019 -----------------------------
1021 ``GET /uri/$DIRCAP/[SUBDIRS../]``
1023 This returns an HTML page, intended to be displayed to a human by a web
1024 browser, which contains HREF links to all files and directories reachable
1025 from this directory. These HREF links do not have a t= argument, meaning
1026 that a human who follows them will get pages also meant for a human. It also
1027 contains forms to upload new files, and to unlink files and directories
1028 from their parent directory. Those forms use POST methods to do their job.
1031 Viewing/Downloading a File
1032 --------------------------
1034 ``GET /uri/$FILECAP``
1036 ``GET /uri/$DIRCAP/[SUBDIRS../]FILENAME``
1038 This will retrieve the contents of the given file. The HTTP response body
1039 will contain the sequence of bytes that make up the file.
1041 If you want the HTTP response to include a useful Content-Type header,
1042 either use the second form (which starts with a $DIRCAP), or add a
1043 "filename=foo" query argument, like "GET /uri/$FILECAP?filename=foo.jpg".
1044 The bare "GET /uri/$FILECAP" does not give the Tahoe node enough information
1045 to determine a Content-Type (since Tahoe immutable files are merely
1046 sequences of bytes, not typed+named file objects).
1048 If the URL has both filename= and "save=true" in the query arguments, then
1049 the server to add a "Content-Disposition: attachment" header, along with a
1050 filename= parameter. When a user clicks on such a link, most browsers will
1051 offer to let the user save the file instead of displaying it inline (indeed,
1052 most browsers will refuse to display it inline). "true", "t", "1", and other
1053 case-insensitive equivalents are all treated the same.
1055 Character-set handling in URLs and HTTP headers is a dubious art [1]_. For
1056 maximum compatibility, Tahoe simply copies the bytes from the filename=
1057 argument into the Content-Disposition header's filename= parameter, without
1058 trying to interpret them in any particular way.
1061 ``GET /named/$FILECAP/FILENAME``
1063 This is an alternate download form which makes it easier to get the correct
1064 filename. The Tahoe server will provide the contents of the given file, with
1065 a Content-Type header derived from the given filename. This form is used to
1066 get browsers to use the "Save Link As" feature correctly, and also helps
1067 command-line tools like "wget" and "curl" use the right filename. Note that
1068 this form can *only* be used with file caps; it is an error to use a
1069 directory cap after the /named/ prefix.
1071 URLs may also use /file/$FILECAP/FILENAME as a synonym for
1072 /named/$FILECAP/FILENAME.
1074 Getting Information About a File Or Directory (as HTML)
1075 -------------------------------------------------------
1077 ``GET /uri/$FILECAP?t=info``
1079 ``GET /uri/$DIRCAP/?t=info``
1081 ``GET /uri/$DIRCAP/[SUBDIRS../]SUBDIR/?t=info``
1083 ``GET /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=info``
1085 This returns a human-oriented HTML page with more detail about the selected
1086 file or directory object. This page contains the following items:
1090 * JSON representation
1091 * raw contents (text/plain)
1092 * access caps (URIs): verify-cap, read-cap, write-cap (for mutable objects)
1093 * check/verify/repair form
1094 * deep-check/deep-size/deep-stats/manifest (for directories)
1095 * replace-contents form (for mutable files)
1098 Creating a Directory
1099 --------------------
1101 ``POST /uri?t=mkdir``
1103 This creates a new empty directory, but does not attach it to the virtual
1106 If a "redirect_to_result=true" argument is provided, then the HTTP response
1107 will cause the web browser to be redirected to a /uri/$DIRCAP page that
1108 gives access to the newly-created directory. If you bookmark this page,
1109 you'll be able to get back to the directory again in the future. This is the
1110 recommended way to start working with a Tahoe server: create a new unlinked
1111 directory (using redirect_to_result=true), then bookmark the resulting
1112 /uri/$DIRCAP page. There is a "create directory" button on the Welcome page
1113 to invoke this action.
1115 This accepts a format= argument in the query string. Refer to the
1116 documentation of the PUT /uri?t=mkdir operation in `Creating A
1117 New Directory`_ for information on the behavior of the format= argument.
1119 If "redirect_to_result=true" is not provided (or is given a value of
1120 "false"), then the HTTP response body will simply be the write-cap of the
1123 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=CHILDNAME``
1125 This creates a new empty directory as a child of the designated SUBDIR. This
1126 will create additional intermediate directories as necessary.
1128 This accepts a format= argument in the query string. Refer to the
1129 documentation of POST /uri/$DIRCAP/[SUBDIRS../]?t=mkdir&name=CHILDNAME in
1130 `Creating a New Directory`_ for information on the behavior of the format=
1133 If a "when_done=URL" argument is provided, the HTTP response will cause the
1134 web browser to redirect to the given URL. This provides a convenient way to
1135 return the browser to the directory that was just modified. Without a
1136 when_done= argument, the HTTP response will simply contain the write-cap of
1137 the directory that was just created.
1143 ``POST /uri?t=upload``
1145 This uploads a file, and produces a file-cap for the contents, but does not
1146 attach the file into the filesystem. No directories will be modified by
1149 The file must be provided as the "file" field of an HTML encoded form body,
1150 produced in response to an HTML form like this::
1152 <form action="/uri" method="POST" enctype="multipart/form-data">
1153 <input type="hidden" name="t" value="upload" />
1154 <input type="file" name="file" />
1155 <input type="submit" value="Upload Unlinked" />
1158 If a "when_done=URL" argument is provided, the response body will cause the
1159 browser to redirect to the given URL. If the when_done= URL has the string
1160 "%(uri)s" in it, that string will be replaced by a URL-escaped form of the
1161 newly created file-cap. (Note that without this substitution, there is no
1162 way to access the file that was just uploaded).
1164 The default (in the absence of when_done=) is to return an HTML page that
1165 describes the results of the upload. This page will contain information
1166 about which storage servers were used for the upload, how long each
1167 operation took, etc.
1169 This accepts format= and mutable=true query string arguments. Refer to
1170 `Writing/Uploading a File`_ for information on the behavior of format= and
1173 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=upload``
1175 This uploads a file, and attaches it as a new child of the given directory,
1176 which must be mutable. The file must be provided as the "file" field of an
1177 HTML-encoded form body, produced in response to an HTML form like this::
1179 <form action="." method="POST" enctype="multipart/form-data">
1180 <input type="hidden" name="t" value="upload" />
1181 <input type="file" name="file" />
1182 <input type="submit" value="Upload" />
1185 A "name=" argument can be provided to specify the new child's name,
1186 otherwise it will be taken from the "filename" field of the upload form
1187 (most web browsers will copy the last component of the original file's
1188 pathname into this field). To avoid confusion, name= is not allowed to
1191 If there is already a child with that name, and it is a mutable file, then
1192 its contents are replaced with the data being uploaded. If it is not a
1193 mutable file, the default behavior is to remove the existing child before
1194 creating a new one. To prevent this (and make the operation return an error
1195 instead of overwriting the old child), add a "replace=false" argument, as
1196 "?t=upload&replace=false". With replace=false, this operation will return an
1197 HTTP 409 "Conflict" error if there is already an object at the given
1198 location, rather than overwriting the existing object. Note that "true",
1199 "t", and "1" are all synonyms for "True", and "false", "f", and "0" are
1200 synonyms for "False". the parameter is case-insensitive.
1202 This will create additional intermediate directories as necessary, although
1203 since it is expected to be triggered by a form that was retrieved by "GET
1204 /uri/$DIRCAP/[SUBDIRS../]", it is likely that the parent directory will
1207 This accepts format= and mutable=true query string arguments. Refer to
1208 `Writing/Uploading a File`_ for information on the behavior of format= and
1211 If a "when_done=URL" argument is provided, the HTTP response will cause the
1212 web browser to redirect to the given URL. This provides a convenient way to
1213 return the browser to the directory that was just modified. Without a
1214 when_done= argument, the HTTP response will simply contain the file-cap of
1215 the file that was just uploaded (a write-cap for mutable files, or a
1216 read-cap for immutable files).
1218 ``POST /uri/$DIRCAP/[SUBDIRS../]FILENAME?t=upload``
1220 This also uploads a file and attaches it as a new child of the given
1221 directory, which must be mutable. It is a slight variant of the previous
1222 operation, as the URL refers to the target file rather than the parent
1223 directory. It is otherwise identical: this accepts mutable= and when_done=
1226 ``POST /uri/$FILECAP?t=upload``
1228 This modifies the contents of an existing mutable file in-place. An error is
1229 signalled if $FILECAP does not refer to a mutable file. It behaves just like
1230 the "PUT /uri/$FILECAP" form, but uses a POST for the benefit of HTML forms
1234 Attaching An Existing File Or Directory (by URI)
1235 ------------------------------------------------
1237 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=uri&name=CHILDNAME&uri=CHILDCAP``
1239 This attaches a given read- or write- cap "CHILDCAP" to the designated
1240 directory, with a specified child name. This behaves much like the PUT t=uri
1241 operation, and is a lot like a UNIX hardlink. It is subject to the same
1242 restrictions as that operation on the use of cap formats unknown to the
1245 This will create additional intermediate directories as necessary, although
1246 since it is expected to be triggered by a form that was retrieved by "GET
1247 /uri/$DIRCAP/[SUBDIRS../]", it is likely that the parent directory will
1250 This accepts the same replace= argument as POST t=upload.
1256 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=delete&name=CHILDNAME``
1258 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=unlink&name=CHILDNAME`` (Tahoe >= v1.9)
1260 This instructs the node to remove a child object (file or subdirectory) from
1261 the given directory, which must be mutable. Note that the entire subtree is
1262 unlinked from the parent. Unlike deleting a subdirectory in a UNIX local
1263 filesystem, the subtree need not be empty; if it isn't, then other references
1264 into the subtree will see that the child subdirectories are not modified by
1265 this operation. Only the link from the given directory to its child is severed.
1267 In Tahoe-LAFS v1.9.0 and later, t=unlink can be used as a synonym for t=delete.
1268 If interoperability with older web-API servers is required, t=delete should
1275 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=rename&from_name=OLD&to_name=NEW``
1277 This instructs the node to rename a child of the given directory, which must
1278 be mutable. This has a similar effect to removing the child, then adding the
1279 same child-cap under the new name, except that it preserves metadata. This
1280 operation cannot move the child to a different directory.
1282 The default behavior is to overwrite any existing link at the destination
1283 (replace=true). To prevent this (and make the operation return an error
1284 instead of overwriting), add a "replace=false" argument. With replace=false,
1285 this operation will return an HTTP 409 "Conflict" error if the destination
1286 is not the same link as the source and there is already a link at the
1287 destination, rather than overwriting the existing link. To allow the
1288 operation to overwrite a link to a file, but return an HTTP 409 error when
1289 trying to overwrite a link to a directory, use "replace=only-files" (this
1290 behavior is closer to the traditional UNIX "mv" command). Note that "true",
1291 "t", and "1" are all synonyms for "True"; "false", "f", and "0" are synonyms
1292 for "False"; and the parameter is case-insensitive.
1295 Relinking ("Moving") a Child
1296 ----------------------------
1298 ``POST /uri/$DIRCAP/[SUBDIRS../]?t=relink&from_name=OLD&to_dir=$NEWDIRCAP/[NEWSUBDIRS../]&to_name=NEW``
1299 ``[&replace=true|false|only-files]`` (Tahoe >= v1.10)
1301 This instructs the node to move a child of the given source directory, into
1302 a different directory and/or to a different name. The command is named
1303 ``relink`` because what it does is add a new link to the child from the new
1304 location, then remove the old link. Nothing is actually "moved": the child
1305 is still reachable through any path from which it was formerly reachable,
1306 and the storage space occupied by its ciphertext is not affected.
1308 The source and destination directories must be writeable. If {{{to_dir}}} is
1309 not present, the child link is renamed within the same directory. If
1310 {{{to_name}}} is not present then it defaults to {{{from_name}}}. If the
1311 destination link (directory and name) is the same as the source link, the
1312 operation has no effect.
1314 Metadata from the source directory entry is preserved. Multiple levels of
1315 descent in the source and destination paths are supported.
1317 This operation will return an HTTP 404 "Not Found" error if
1318 ``$DIRCAP/[SUBDIRS../]``, the child being moved, or the destination
1319 directory does not exist. It will return an HTTP 400 "Bad Request" error
1320 if any entry in the source or destination paths is not a directory.
1322 The default behavior is to overwrite any existing link at the destination
1323 (replace=true). To prevent this (and make the operation return an error
1324 instead of overwriting), add a "replace=false" argument. With replace=false,
1325 this operation will return an HTTP 409 "Conflict" error if the destination
1326 is not the same link as the source and there is already a link at the
1327 destination, rather than overwriting the existing link. To allow the
1328 operation to overwrite a link to a file, but return an HTTP 409 error when
1329 trying to overwrite a link to a directory, use "replace=only-files" (this
1330 behavior is closer to the traditional UNIX "mv" command). Note that "true",
1331 "t", and "1" are all synonyms for "True"; "false", "f", and "0" are synonyms
1332 for "False"; and the parameter is case-insensitive.
1334 When relinking into a different directory, for safety, the child link is
1335 not removed from the old directory until it has been successfully added to
1336 the new directory. This implies that in case of a crash or failure, the
1337 link to the child will not be lost, but it could be linked at both the old
1340 The source link should not be the same as any link (directory and child name)
1341 in the ``to_dir`` path. This restriction is not enforced, but it may be
1342 enforced in a future version. If it were violated then the result would be
1343 to create a cycle in the directory structure that is not necessarily reachable
1344 from the root of the destination path (``$NEWDIRCAP``), which could result in
1345 data loss, as described in ticket `#943`_.
1347 .. _`#943`: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/943
1353 ``GET /uri?uri=$CAP``
1355 This causes a redirect to /uri/$CAP, and retains any additional query
1356 arguments (like filename= or save=). This is for the convenience of web
1357 forms which allow the user to paste in a read- or write- cap (obtained
1358 through some out-of-band channel, like IM or email).
1360 Note that this form merely redirects to the specific file or directory
1361 indicated by the $CAP: unlike the GET /uri/$DIRCAP form, you cannot
1362 traverse to children by appending additional path segments to the URL.
1364 ``GET /uri/$DIRCAP/[SUBDIRS../]?t=rename-form&name=$CHILDNAME``
1366 This provides a useful facility to browser-based user interfaces. It
1367 returns a page containing a form targetting the "POST $DIRCAP t=rename"
1368 functionality described above, with the provided $CHILDNAME present in the
1369 'from_name' field of that form. I.e. this presents a form offering to
1370 rename $CHILDNAME, requesting the new name, and submitting POST rename.
1371 This same URL format can also be used with "move-form" with the expected
1374 ``GET /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=uri``
1376 This returns the file- or directory- cap for the specified object.
1378 ``GET /uri/$DIRCAP/[SUBDIRS../]CHILDNAME?t=readonly-uri``
1380 This returns a read-only file- or directory- cap for the specified object.
1381 If the object is an immutable file, this will return the same value as
1385 Debugging and Testing Features
1386 ------------------------------
1388 These URLs are less-likely to be helpful to the casual Tahoe user, and are
1389 mainly intended for developers.
1391 ``POST $URL?t=check``
1393 This triggers the FileChecker to determine the current "health" of the
1394 given file or directory, by counting how many shares are available. The
1395 page that is returned will display the results. This can be used as a "show
1396 me detailed information about this file" page.
1398 If a verify=true argument is provided, the node will perform a more
1399 intensive check, downloading and verifying every single bit of every share.
1401 If an add-lease=true argument is provided, the node will also add (or
1402 renew) a lease to every share it encounters. Each lease will keep the share
1403 alive for a certain period of time (one month by default). Once the last
1404 lease expires or is explicitly cancelled, the storage server is allowed to
1407 If an output=JSON argument is provided, the response will be
1408 machine-readable JSON instead of human-oriented HTML. The data is a
1409 dictionary with the following keys::
1411 storage-index: a base32-encoded string with the objects's storage index,
1412 or an empty string for LIT files
1413 summary: a string, with a one-line summary of the stats of the file
1414 results: a dictionary that describes the state of the file. For LIT files,
1415 this dictionary has only the 'healthy' key, which will always be
1416 True. For distributed files, this dictionary has the following
1418 count-happiness: the servers-of-happiness level of the file, as
1419 defined in `docs/specifications/servers-of-happiness.rst`_.
1420 count-shares-good: the number of good shares that were found
1421 count-shares-needed: 'k', the number of shares required for recovery
1422 count-shares-expected: 'N', the number of total shares generated
1423 count-good-share-hosts: the number of distinct storage servers with
1424 good shares. Note that a high value does not
1425 necessarily imply good share distribution,
1426 because some of these servers may only hold
1428 count-wrong-shares: for mutable files, the number of shares for
1429 versions other than the 'best' one (highest
1430 sequence number, highest roothash). These are
1431 either old, or created by an uncoordinated or
1432 not fully successful write.
1433 count-recoverable-versions: for mutable files, the number of
1434 recoverable versions of the file. For
1435 a healthy file, this will equal 1.
1436 count-unrecoverable-versions: for mutable files, the number of
1437 unrecoverable versions of the file.
1438 For a healthy file, this will be 0.
1439 count-corrupt-shares: the number of shares with integrity failures
1440 list-corrupt-shares: a list of "share locators", one for each share
1441 that was found to be corrupt. Each share locator
1442 is a list of (serverid, storage_index, sharenum).
1443 servers-responding: list of base32-encoded storage server identifiers,
1444 one for each server which responded to the share
1446 healthy: (bool) True if the file is completely healthy, False otherwise.
1447 Healthy files have at least N good shares. Overlapping shares
1448 do not currently cause a file to be marked unhealthy. If there
1449 are at least N good shares, then corrupt shares do not cause the
1450 file to be marked unhealthy, although the corrupt shares will be
1451 listed in the results (list-corrupt-shares) and should be manually
1452 removed to wasting time in subsequent downloads (as the
1453 downloader rediscovers the corruption and uses alternate shares).
1454 Future compatibility: the meaning of this field may change to
1455 reflect whether the servers-of-happiness criterion is met
1457 sharemap: dict mapping share identifier to list of serverids
1458 (base32-encoded strings). This indicates which servers are
1459 holding which shares. For immutable files, the shareid is
1460 an integer (the share number, from 0 to N-1). For
1461 immutable files, it is a string of the form
1462 'seq%d-%s-sh%d', containing the sequence number, the
1463 roothash, and the share number.
1465 Before Tahoe-LAFS v1.11, the `results` dictionary also had a `needs-rebalancing`
1466 field, but that has been removed since it was computed incorrectly.
1468 .. _`docs/specifications/servers-of-happiness.rst`: ../specifications/servers-of-happiness.rst
1471 ``POST $URL?t=start-deep-check`` (must add &ophandle=XYZ)
1473 This initiates a recursive walk of all files and directories reachable from
1474 the target, performing a check on each one just like t=check. The result
1475 page will contain a summary of the results, including details on any
1476 file/directory that was not fully healthy.
1478 t=start-deep-check can only be invoked on a directory. An error (400
1479 BAD_REQUEST) will be signalled if it is invoked on a file. The recursive
1480 walker will deal with loops safely.
1482 This accepts the same verify= and add-lease= arguments as t=check.
1484 Since this operation can take a long time (perhaps a second per object),
1485 the ophandle= argument is required (see "Slow Operations, Progress, and
1486 Cancelling" above). The response to this POST will be a redirect to the
1487 corresponding /operations/$HANDLE page (with output=HTML or output=JSON to
1488 match the output= argument given to the POST). The deep-check operation
1489 will continue to run in the background, and the /operations page should be
1490 used to find out when the operation is done.
1492 Detailed check results for non-healthy files and directories will be
1493 available under /operations/$HANDLE/$STORAGEINDEX, and the HTML status will
1494 contain links to these detailed results.
1496 The HTML /operations/$HANDLE page for incomplete operations will contain a
1497 meta-refresh tag, set to 60 seconds, so that a browser which uses
1498 deep-check will automatically poll until the operation has completed.
1500 The JSON page (/options/$HANDLE?output=JSON) will contain a
1501 machine-readable JSON dictionary with the following keys::
1503 finished: a boolean, True if the operation is complete, else False. Some
1504 of the remaining keys may not be present until the operation
1506 root-storage-index: a base32-encoded string with the storage index of the
1507 starting point of the deep-check operation
1508 count-objects-checked: count of how many objects were checked. Note that
1509 non-distributed objects (i.e. small immutable LIT
1510 files) are not checked, since for these objects,
1511 the data is contained entirely in the URI.
1512 count-objects-healthy: how many of those objects were completely healthy
1513 count-objects-unhealthy: how many were damaged in some way
1514 count-corrupt-shares: how many shares were found to have corruption,
1515 summed over all objects examined
1516 list-corrupt-shares: a list of "share identifiers", one for each share
1517 that was found to be corrupt. Each share identifier
1518 is a list of (serverid, storage_index, sharenum).
1519 list-unhealthy-files: a list of (pathname, check-results) tuples, for
1520 each file that was not fully healthy. 'pathname' is
1521 a list of strings (which can be joined by "/"
1522 characters to turn it into a single string),
1523 relative to the directory on which deep-check was
1524 invoked. The 'check-results' field is the same as
1525 that returned by t=check&output=JSON, described
1527 stats: a dictionary with the same keys as the t=start-deep-stats command
1530 ``POST $URL?t=stream-deep-check``
1532 This initiates a recursive walk of all files and directories reachable from
1533 the target, performing a check on each one just like t=check. For each
1534 unique object (duplicates are skipped), a single line of JSON is emitted to
1535 the HTTP response channel (or an error indication, see below). When the walk
1536 is complete, a final line of JSON is emitted which contains the accumulated
1537 file-size/count "deep-stats" data.
1539 This command takes the same arguments as t=start-deep-check.
1541 A CLI tool can split the response stream on newlines into "response units",
1542 and parse each response unit as JSON. Each such parsed unit will be a
1543 dictionary, and will contain at least the "type" key: a string, one of
1544 "file", "directory", or "stats".
1546 For all units that have a type of "file" or "directory", the dictionary will
1547 contain the following keys::
1549 "path": a list of strings, with the path that is traversed to reach the
1551 "cap": a write-cap URI for the file or directory, if available, else a
1553 "verifycap": a verify-cap URI for the file or directory
1554 "repaircap": an URI for the weakest cap that can still be used to repair
1556 "storage-index": a base32 storage index for the object
1557 "check-results": a copy of the dictionary which would be returned by
1558 t=check&output=json, with three top-level keys:
1559 "storage-index", "summary", and "results", and a variety
1560 of counts and sharemaps in the "results" value.
1562 Note that non-distributed files (i.e. LIT files) will have values of None
1563 for verifycap, repaircap, and storage-index, since these files can neither
1564 be verified nor repaired, and are not stored on the storage servers.
1565 Likewise the check-results dictionary will be limited: an empty string for
1566 storage-index, and a results dictionary with only the "healthy" key.
1568 The last unit in the stream will have a type of "stats", and will contain
1569 the keys described in the "start-deep-stats" operation, below.
1571 If any errors occur during the traversal (specifically if a directory is
1572 unrecoverable, such that further traversal is not possible), an error
1573 indication is written to the response body, instead of the usual line of
1574 JSON. This error indication line will begin with the string "ERROR:" (in all
1575 caps), and contain a summary of the error on the rest of the line. The
1576 remaining lines of the response body will be a python exception. The client
1577 application should look for the ERROR: and stop processing JSON as soon as
1578 it is seen. Note that neither a file being unrecoverable nor a directory
1579 merely being unhealthy will cause traversal to stop. The line just before
1580 the ERROR: will describe the directory that was untraversable, since the
1581 unit is emitted to the HTTP response body before the child is traversed.
1584 ``POST $URL?t=check&repair=true``
1586 This performs a health check of the given file or directory, and if the
1587 checker determines that the object is not healthy (some shares are missing
1588 or corrupted), it will perform a "repair". During repair, any missing
1589 shares will be regenerated and uploaded to new servers.
1591 This accepts the same verify=true and add-lease= arguments as t=check. When
1592 an output=JSON argument is provided, the machine-readable JSON response
1593 will contain the following keys::
1595 storage-index: a base32-encoded string with the objects's storage index,
1596 or an empty string for LIT files
1597 repair-attempted: (bool) True if repair was attempted
1598 repair-successful: (bool) True if repair was attempted and the file was
1599 fully healthy afterwards. False if no repair was
1600 attempted, or if a repair attempt failed.
1601 pre-repair-results: a dictionary that describes the state of the file
1602 before any repair was performed. This contains exactly
1603 the same keys as the 'results' value of the t=check
1604 response, described above.
1605 post-repair-results: a dictionary that describes the state of the file
1606 after any repair was performed. If no repair was
1607 performed, post-repair-results and pre-repair-results
1608 will be the same. This contains exactly the same keys
1609 as the 'results' value of the t=check response,
1612 ``POST $URL?t=start-deep-check&repair=true`` (must add &ophandle=XYZ)
1614 This triggers a recursive walk of all files and directories, performing a
1615 t=check&repair=true on each one.
1617 Like t=start-deep-check without the repair= argument, this can only be
1618 invoked on a directory. An error (400 BAD_REQUEST) will be signalled if it
1619 is invoked on a file. The recursive walker will deal with loops safely.
1621 This accepts the same verify= and add-lease= arguments as
1622 t=start-deep-check. It uses the same ophandle= mechanism as
1623 start-deep-check. When an output=JSON argument is provided, the response
1624 will contain the following keys::
1626 finished: (bool) True if the operation has completed, else False
1627 root-storage-index: a base32-encoded string with the storage index of the
1628 starting point of the deep-check operation
1629 count-objects-checked: count of how many objects were checked
1631 count-objects-healthy-pre-repair: how many of those objects were completely
1632 healthy, before any repair
1633 count-objects-unhealthy-pre-repair: how many were damaged in some way
1634 count-objects-healthy-post-repair: how many of those objects were completely
1635 healthy, after any repair
1636 count-objects-unhealthy-post-repair: how many were damaged in some way
1638 count-repairs-attempted: repairs were attempted on this many objects.
1639 count-repairs-successful: how many repairs resulted in healthy objects
1640 count-repairs-unsuccessful: how many repairs resulted did not results in
1641 completely healthy objects
1642 count-corrupt-shares-pre-repair: how many shares were found to have
1643 corruption, summed over all objects
1644 examined, before any repair
1645 count-corrupt-shares-post-repair: how many shares were found to have
1646 corruption, summed over all objects
1647 examined, after any repair
1648 list-corrupt-shares: a list of "share identifiers", one for each share
1649 that was found to be corrupt (before any repair).
1650 Each share identifier is a list of (serverid,
1651 storage_index, sharenum).
1652 list-remaining-corrupt-shares: like list-corrupt-shares, but mutable shares
1653 that were successfully repaired are not
1654 included. These are shares that need
1655 manual processing. Since immutable shares
1656 cannot be modified by clients, all corruption
1657 in immutable shares will be listed here.
1658 list-unhealthy-files: a list of (pathname, check-results) tuples, for
1659 each file that was not fully healthy. 'pathname' is
1660 relative to the directory on which deep-check was
1661 invoked. The 'check-results' field is the same as
1662 that returned by t=check&repair=true&output=JSON,
1664 stats: a dictionary with the same keys as the t=start-deep-stats command
1667 ``POST $URL?t=stream-deep-check&repair=true``
1669 This triggers a recursive walk of all files and directories, performing a
1670 t=check&repair=true on each one. For each unique object (duplicates are
1671 skipped), a single line of JSON is emitted to the HTTP response channel (or
1672 an error indication). When the walk is complete, a final line of JSON is
1673 emitted which contains the accumulated file-size/count "deep-stats" data.
1675 This emits the same data as t=stream-deep-check (without the repair=true),
1676 except that the "check-results" field is replaced with a
1677 "check-and-repair-results" field, which contains the keys returned by
1678 t=check&repair=true&output=json (i.e. repair-attempted, repair-successful,
1679 pre-repair-results, and post-repair-results). The output does not contain
1680 the summary dictionary that is provied by t=start-deep-check&repair=true
1681 (the one with count-objects-checked and list-unhealthy-files), since the
1682 receiving client is expected to calculate those values itself from the
1683 stream of per-object check-and-repair-results.
1685 Note that the "ERROR:" indication will only be emitted if traversal stops,
1686 which will only occur if an unrecoverable directory is encountered. If a
1687 file or directory repair fails, the traversal will continue, and the repair
1688 failure will be indicated in the JSON data (in the "repair-successful" key).
1690 ``POST $DIRURL?t=start-manifest`` (must add &ophandle=XYZ)
1692 This operation generates a "manfest" of the given directory tree, mostly
1693 for debugging. This is a table of (path, filecap/dircap), for every object
1694 reachable from the starting directory. The path will be slash-joined, and
1695 the filecap/dircap will contain a link to the object in question. This page
1696 gives immediate access to every object in the virtual filesystem subtree.
1698 This operation uses the same ophandle= mechanism as deep-check. The
1699 corresponding /operations/$HANDLE page has three different forms. The
1700 default is output=HTML.
1702 If output=text is added to the query args, the results will be a text/plain
1703 list. The first line is special: it is either "finished: yes" or "finished:
1704 no"; if the operation is not finished, you must periodically reload the
1705 page until it completes. The rest of the results are a plaintext list, with
1706 one file/dir per line, slash-separated, with the filecap/dircap separated
1709 If output=JSON is added to the queryargs, then the results will be a
1710 JSON-formatted dictionary with six keys. Note that because large directory
1711 structures can result in very large JSON results, the full results will not
1712 be available until the operation is complete (i.e. until output["finished"]
1715 finished (bool): if False then you must reload the page until True
1716 origin_si (base32 str): the storage index of the starting point
1717 manifest: list of (path, cap) tuples, where path is a list of strings.
1718 verifycaps: list of (printable) verify cap strings
1719 storage-index: list of (base32) storage index strings
1720 stats: a dictionary with the same keys as the t=start-deep-stats command
1723 ``POST $DIRURL?t=start-deep-size`` (must add &ophandle=XYZ)
1725 This operation generates a number (in bytes) containing the sum of the
1726 filesize of all directories and immutable files reachable from the given
1727 directory. This is a rough lower bound of the total space consumed by this
1728 subtree. It does not include space consumed by mutable files, nor does it
1729 take expansion or encoding overhead into account. Later versions of the
1730 code may improve this estimate upwards.
1732 The /operations/$HANDLE status output consists of two lines of text::
1737 ``POST $DIRURL?t=start-deep-stats`` (must add &ophandle=XYZ)
1739 This operation performs a recursive walk of all files and directories
1740 reachable from the given directory, and generates a collection of
1741 statistics about those objects.
1743 The result (obtained from the /operations/$OPHANDLE page) is a
1744 JSON-serialized dictionary with the following keys (note that some of these
1745 keys may be missing until 'finished' is True)::
1747 finished: (bool) True if the operation has finished, else False
1748 count-immutable-files: count of how many CHK files are in the set
1749 count-mutable-files: same, for mutable files (does not include directories)
1750 count-literal-files: same, for LIT files (data contained inside the URI)
1751 count-files: sum of the above three
1752 count-directories: count of directories
1753 count-unknown: count of unrecognized objects (perhaps from the future)
1754 size-immutable-files: total bytes for all CHK files in the set, =deep-size
1755 size-mutable-files (TODO): same, for current version of all mutable files
1756 size-literal-files: same, for LIT files
1757 size-directories: size of directories (includes size-literal-files)
1758 size-files-histogram: list of (minsize, maxsize, count) buckets,
1759 with a histogram of filesizes, 5dB/bucket,
1760 for both literal and immutable files
1761 largest-directory: number of children in the largest directory
1762 largest-immutable-file: number of bytes in the largest CHK file
1764 size-mutable-files is not implemented, because it would require extra
1765 queries to each mutable file to get their size. This may be implemented in
1768 Assuming no sharing, the basic space consumed by a single root directory is
1769 the sum of size-immutable-files, size-mutable-files, and size-directories.
1770 The actual disk space used by the shares is larger, because of the
1771 following sources of overhead::
1774 expansion due to erasure coding
1775 share management data (leases)
1776 backend (ext3) minimum block size
1778 ``POST $URL?t=stream-manifest``
1780 This operation performs a recursive walk of all files and directories
1781 reachable from the given starting point. For each such unique object
1782 (duplicates are skipped), a single line of JSON is emitted to the HTTP
1783 response channel (or an error indication, see below). When the walk is
1784 complete, a final line of JSON is emitted which contains the accumulated
1785 file-size/count "deep-stats" data.
1787 A CLI tool can split the response stream on newlines into "response units",
1788 and parse each response unit as JSON. Each such parsed unit will be a
1789 dictionary, and will contain at least the "type" key: a string, one of
1790 "file", "directory", or "stats".
1792 For all units that have a type of "file" or "directory", the dictionary will
1793 contain the following keys::
1795 "path": a list of strings, with the path that is traversed to reach the
1797 "cap": a write-cap URI for the file or directory, if available, else a
1799 "verifycap": a verify-cap URI for the file or directory
1800 "repaircap": an URI for the weakest cap that can still be used to repair
1802 "storage-index": a base32 storage index for the object
1804 Note that non-distributed files (i.e. LIT files) will have values of None
1805 for verifycap, repaircap, and storage-index, since these files can neither
1806 be verified nor repaired, and are not stored on the storage servers.
1808 The last unit in the stream will have a type of "stats", and will contain
1809 the keys described in the "start-deep-stats" operation, below.
1811 If any errors occur during the traversal (specifically if a directory is
1812 unrecoverable, such that further traversal is not possible), an error
1813 indication is written to the response body, instead of the usual line of
1814 JSON. This error indication line will begin with the string "ERROR:" (in all
1815 caps), and contain a summary of the error on the rest of the line. The
1816 remaining lines of the response body will be a python exception. The client
1817 application should look for the ERROR: and stop processing JSON as soon as
1818 it is seen. The line just before the ERROR: will describe the directory that
1819 was untraversable, since the manifest entry is emitted to the HTTP response
1820 body before the child is traversed.
1826 The portion of the web namespace that begins with "/uri" (and "/named") is
1827 dedicated to giving users (both humans and programs) access to the Tahoe
1828 virtual filesystem. The rest of the namespace provides status information
1829 about the state of the Tahoe node.
1831 ``GET /`` (the root page)
1833 This is the "Welcome Page", and contains a few distinct sections::
1835 Node information: library versions, local nodeid, services being provided.
1837 Filesystem Access Forms: create a new directory, view a file/directory by
1838 URI, upload a file (unlinked), download a file by
1841 Grid Status: introducer information, helper information, connected storage
1846 This page lists all active uploads and downloads, and contains a short list
1847 of recent upload/download operations. Each operation has a link to a page
1848 that describes file sizes, servers that were involved, and the time consumed
1849 in each phase of the operation.
1851 A GET of /status/?t=json will contain a machine-readable subset of the same
1852 data. It returns a JSON-encoded dictionary. The only key defined at this
1853 time is "active", with a value that is a list of operation dictionaries, one
1854 for each active operation. Once an operation is completed, it will no longer
1855 appear in data["active"] .
1857 Each op-dict contains a "type" key, one of "upload", "download",
1858 "mapupdate", "publish", or "retrieve" (the first two are for immutable
1859 files, while the latter three are for mutable files and directories).
1861 The "upload" op-dict will contain the following keys::
1863 type (string): "upload"
1864 storage-index-string (string): a base32-encoded storage index
1865 total-size (int): total size of the file
1866 status (string): current status of the operation
1867 progress-hash (float): 1.0 when the file has been hashed
1868 progress-ciphertext (float): 1.0 when the file has been encrypted.
1869 progress-encode-push (float): 1.0 when the file has been encoded and
1870 pushed to the storage servers. For helper
1871 uploads, the ciphertext value climbs to 1.0
1872 first, then encoding starts. For unassisted
1873 uploads, ciphertext and encode-push progress
1874 will climb at the same pace.
1876 The "download" op-dict will contain the following keys::
1878 type (string): "download"
1879 storage-index-string (string): a base32-encoded storage index
1880 total-size (int): total size of the file
1881 status (string): current status of the operation
1882 progress (float): 1.0 when the file has been fully downloaded
1884 Front-ends which want to report progress information are advised to simply
1885 average together all the progress-* indicators. A slightly more accurate
1886 value can be found by ignoring the progress-hash value (since the current
1887 implementation hashes synchronously, so clients will probably never see
1888 progress-hash!=1.0).
1890 ``GET /helper_status/``
1892 If the node is running a helper (i.e. if [helper]enabled is set to True in
1893 tahoe.cfg), then this page will provide a list of all the helper operations
1894 currently in progress. If "?t=json" is added to the URL, it will return a
1895 JSON-formatted list of helper statistics, which can then be used to produce
1896 graphs to indicate how busy the helper is.
1898 ``GET /statistics/``
1900 This page provides "node statistics", which are collected from a variety of
1903 load_monitor: every second, the node schedules a timer for one second in
1904 the future, then measures how late the subsequent callback
1905 is. The "load_average" is this tardiness, measured in
1906 seconds, averaged over the last minute. It is an indication
1907 of a busy node, one which is doing more work than can be
1908 completed in a timely fashion. The "max_load" value is the
1909 highest value that has been seen in the last 60 seconds.
1911 cpu_monitor: every minute, the node uses time.clock() to measure how much
1912 CPU time it has used, and it uses this value to produce
1913 1min/5min/15min moving averages. These values range from 0%
1914 (0.0) to 100% (1.0), and indicate what fraction of the CPU
1915 has been used by the Tahoe node. Not all operating systems
1916 provide meaningful data to time.clock(): they may report 100%
1917 CPU usage at all times.
1919 uploader: this counts how many immutable files (and bytes) have been
1920 uploaded since the node was started
1922 downloader: this counts how many immutable files have been downloaded
1923 since the node was started
1925 publishes: this counts how many mutable files (including directories) have
1926 been modified since the node was started
1928 retrieves: this counts how many mutable files (including directories) have
1929 been read since the node was started
1931 There are other statistics that are tracked by the node. The "raw stats"
1932 section shows a formatted dump of all of them.
1934 By adding "?t=json" to the URL, the node will return a JSON-formatted
1935 dictionary of stats values, which can be used by other tools to produce
1936 graphs of node behavior. The misc/munin/ directory in the source
1937 distribution provides some tools to produce these graphs.
1939 ``GET /`` (introducer status)
1941 For Introducer nodes, the welcome page displays information about both
1942 clients and servers which are connected to the introducer. Servers make
1943 "service announcements", and these are listed in a table. Clients will
1944 subscribe to hear about service announcements, and these subscriptions are
1945 listed in a separate table. Both tables contain information about what
1946 version of Tahoe is being run by the remote node, their advertised and
1947 outbound IP addresses, their nodeid and nickname, and how long they have
1950 By adding "?t=json" to the URL, the node will return a JSON-formatted
1951 dictionary of stats values, which can be used to produce graphs of connected
1952 clients over time. This dictionary has the following keys::
1954 ["subscription_summary"] : a dictionary mapping service name (like
1955 "storage") to an integer with the number of
1956 clients that have subscribed to hear about that
1958 ["announcement_summary"] : a dictionary mapping service name to an integer
1959 with the number of servers which are announcing
1961 ["announcement_distinct_hosts"] : a dictionary mapping service name to an
1962 integer which represents the number of
1963 distinct hosts that are providing that
1964 service. If two servers have announced
1965 FURLs which use the same hostnames (but
1966 different ports and tubids), they are
1967 considered to be on the same host.
1970 Static Files in /public_html
1971 ============================
1973 The web-API server will take any request for a URL that starts with /static
1974 and serve it from a configurable directory which defaults to
1975 $BASEDIR/public_html . This is configured by setting the "[node]web.static"
1976 value in $BASEDIR/tahoe.cfg . If this is left at the default value of
1977 "public_html", then http://127.0.0.1:3456/static/subdir/foo.html will be
1978 served with the contents of the file $BASEDIR/public_html/subdir/foo.html .
1980 This can be useful to serve a javascript application which provides a
1981 prettier front-end to the rest of the Tahoe web-API.
1984 Safety and Security Issues -- Names vs. URIs
1985 ============================================
1987 Summary: use explicit file- and dir- caps whenever possible, to reduce the
1988 potential for surprises when the filesystem structure is changed.
1990 Tahoe provides a mutable filesystem, but the ways that the filesystem can
1991 change are limited. The only thing that can change is that the mapping from
1992 child names to child objects that each directory contains can be changed by
1993 adding a new child name pointing to an object, removing an existing child name,
1994 or changing an existing child name to point to a different object.
1996 Obviously if you query Tahoe for information about the filesystem and then act
1997 to change the filesystem (such as by getting a listing of the contents of a
1998 directory and then adding a file to the directory), then the filesystem might
1999 have been changed after you queried it and before you acted upon it. However,
2000 if you use the URI instead of the pathname of an object when you act upon the
2001 object, then the only change that can happen is if the object is a directory
2002 then the set of child names it has might be different. If, on the other hand,
2003 you act upon the object using its pathname, then a different object might be in
2004 that place, which can result in more kinds of surprises.
2006 For example, suppose you are writing code which recursively downloads the
2007 contents of a directory. The first thing your code does is fetch the listing
2008 of the contents of the directory. For each child that it fetched, if that
2009 child is a file then it downloads the file, and if that child is a directory
2010 then it recurses into that directory. Now, if the download and the recurse
2011 actions are performed using the child's name, then the results might be
2012 wrong, because for example a child name that pointed to a sub-directory when
2013 you listed the directory might have been changed to point to a file (in which
2014 case your attempt to recurse into it would result in an error and the file
2015 would be skipped), or a child name that pointed to a file when you listed the
2016 directory might now point to a sub-directory (in which case your attempt to
2017 download the child would result in a file containing HTML text describing the
2020 If your recursive algorithm uses the uri of the child instead of the name of
2021 the child, then those kinds of mistakes just can't happen. Note that both the
2022 child's name and the child's URI are included in the results of listing the
2023 parent directory, so it isn't any harder to use the URI for this purpose.
2025 The read and write caps in a given directory node are separate URIs, and
2026 can't be assumed to point to the same object even if they were retrieved in
2027 the same operation (although the web-API server attempts to ensure this
2028 in most cases). If you need to rely on that property, you should explicitly
2029 verify it. More generally, you should not make assumptions about the
2030 internal consistency of the contents of mutable directories. As a result
2031 of the signatures on mutable object versions, it is guaranteed that a given
2032 version was written in a single update, but -- as in the case of a file --
2033 the contents may have been chosen by a malicious writer in a way that is
2034 designed to confuse applications that rely on their consistency.
2036 In general, use names if you want "whatever object (whether file or
2037 directory) is found by following this name (or sequence of names) when my
2038 request reaches the server". Use URIs if you want "this particular object".
2044 Tahoe uses both mutable and immutable files. Mutable files can be created
2045 explicitly by doing an upload with ?mutable=true added, or implicitly by
2046 creating a new directory (since a directory is just a special way to
2047 interpret a given mutable file).
2049 Mutable files suffer from the same consistency-vs-availability tradeoff that
2050 all distributed data storage systems face. It is not possible to
2051 simultaneously achieve perfect consistency and perfect availability in the
2052 face of network partitions (servers being unreachable or faulty).
2054 Tahoe tries to achieve a reasonable compromise, but there is a basic rule in
2055 place, known as the Prime Coordination Directive: "Don't Do That". What this
2056 means is that if write-access to a mutable file is available to several
2057 parties, then those parties are responsible for coordinating their activities
2058 to avoid multiple simultaneous updates. This could be achieved by having
2059 these parties talk to each other and using some sort of locking mechanism, or
2060 by serializing all changes through a single writer.
2062 The consequences of performing uncoordinated writes can vary. Some of the
2063 writers may lose their changes, as somebody else wins the race condition. In
2064 many cases the file will be left in an "unhealthy" state, meaning that there
2065 are not as many redundant shares as we would like (reducing the reliability
2066 of the file against server failures). In the worst case, the file can be left
2067 in such an unhealthy state that no version is recoverable, even the old ones.
2068 It is this small possibility of data loss that prompts us to issue the Prime
2069 Coordination Directive.
2071 Tahoe nodes implement internal serialization to make sure that a single Tahoe
2072 node cannot conflict with itself. For example, it is safe to issue two
2073 directory modification requests to a single tahoe node's web-API server at the
2074 same time, because the Tahoe node will internally delay one of them until
2075 after the other has finished being applied. (This feature was introduced in
2076 Tahoe-1.1; back with Tahoe-1.0 the web client was responsible for serializing
2077 web requests themselves).
2079 For more details, please see the "Consistency vs Availability" and "The Prime
2080 Coordination Directive" sections of mutable.rst_.
2082 .. _mutable.rst: ../specifications/mutable.rst
2088 Gateway nodes may find it necessary to prohibit access to certain files. The
2089 web-API has a facility to block access to filecaps by their storage index,
2090 returning a 403 "Forbidden" error instead of the original file.
2092 This blacklist is recorded in $NODEDIR/access.blacklist, and contains one
2093 blocked file per line. Comment lines (starting with ``#``) are ignored. Each
2094 line consists of the storage-index (in the usual base32 format as displayed
2095 by the "More Info" page, or by the "tahoe debug dump-cap" command), followed
2096 by whitespace, followed by a reason string, which will be included in the 403
2097 error message. This could hold a URL to a page that explains why the file is
2098 blocked, for example.
2100 So for example, if you found a need to block access to a file with filecap
2101 ``URI:CHK:n7r3m6wmomelk4sep3kw5cvduq:os7ijw5c3maek7pg65e5254k2fzjflavtpejjyhshpsxuqzhcwwq:3:20:14861``,
2102 you could do the following::
2104 tahoe debug dump-cap URI:CHK:n7r3m6wmomelk4sep3kw5cvduq:os7ijw5c3maek7pg65e5254k2fzjflavtpejjyhshpsxuqzhcwwq:3:20:14861
2105 -> storage index: whpepioyrnff7orecjolvbudeu
2106 echo "whpepioyrnff7orecjolvbudeu my puppy told me to" >>$NODEDIR/access.blacklist
2107 tahoe restart $NODEDIR
2108 tahoe get URI:CHK:n7r3m6wmomelk4sep3kw5cvduq:os7ijw5c3maek7pg65e5254k2fzjflavtpejjyhshpsxuqzhcwwq:3:20:14861
2109 -> error, 403 Access Prohibited: my puppy told me to
2111 The ``access.blacklist`` file will be checked each time a file or directory
2112 is accessed: the file's ``mtime`` is used to decide whether it need to be
2113 reloaded. Therefore no node restart is necessary when creating the initial
2114 blacklist, nor when adding second, third, or additional entries to the list.
2115 When modifying the file, be careful to update it atomically, otherwise a
2116 request may arrive while the file is only halfway written, and the partial
2117 file may be incorrectly parsed.
2119 The blacklist is applied to all access paths (including SFTP, FTP, and CLI
2120 operations), not just the web-API. The blacklist also applies to directories.
2121 If a directory is blacklisted, the gateway will refuse access to both that
2122 directory and any child files/directories underneath it, when accessed via
2123 "DIRCAP/SUBDIR/FILENAME" -style URLs. Users who go directly to the child
2124 file/dir will bypass the blacklist.
2126 The node will log the SI of the file being blocked, and the reason code, into
2127 the ``logs/twistd.log`` file.
2130 .. [1] URLs and HTTP and UTF-8, Oh My
2132 HTTP does not provide a mechanism to specify the character set used to
2133 encode non-ASCII names in URLs (`RFC3986#2.1`_). We prefer the convention
2134 that the ``filename=`` argument shall be a URL-escaped UTF-8 encoded Unicode
2135 string. For example, suppose we want to provoke the server into using a
2136 filename of "f i a n c e-acute e" (i.e. f i a n c U+00E9 e). The UTF-8
2137 encoding of this is 0x66 0x69 0x61 0x6e 0x63 0xc3 0xa9 0x65 (or
2138 "fianc\\xC3\\xA9e", as python's ``repr()`` function would show). To encode
2139 this into a URL, the non-printable characters must be escaped with the
2140 urlencode ``%XX`` mechanism, giving us "fianc%C3%A9e". Thus, the first line
2141 of the HTTP request will be "``GET
2142 /uri/CAP...?save=true&filename=fianc%C3%A9e HTTP/1.1``". Not all browsers
2143 provide this: IE7 by default uses the Latin-1 encoding, which is "fianc%E9e"
2144 (although it has a configuration option to send URLs as UTF-8).
2146 The response header will need to indicate a non-ASCII filename. The actual
2147 mechanism to do this is not clear. For ASCII filenames, the response header
2150 Content-Disposition: attachment; filename="english.txt"
2152 If Tahoe were to enforce the UTF-8 convention, it would need to decode the
2153 URL argument into a Unicode string, and then encode it back into a sequence
2154 of bytes when creating the response header. One possibility would be to use
2155 unencoded UTF-8. Developers suggest that IE7 might accept this::
2157 #1: Content-Disposition: attachment; filename="fianc\xC3\xA9e"
2158 (note, the last four bytes of that line, not including the newline, are
2159 0xC3 0xA9 0x65 0x22)
2161 `RFC2231#4`_ (dated 1997): suggests that the following might work, and `some
2162 developers have reported`_ that it is supported by Firefox (but not IE7)::
2164 #2: Content-Disposition: attachment; filename*=utf-8''fianc%C3%A9e
2166 My reading of `RFC2616#19.5.1`_ (which defines Content-Disposition) says
2167 that the filename= parameter is defined to be wrapped in quotes (presumably
2168 to allow spaces without breaking the parsing of subsequent parameters),
2169 which would give us::
2171 #3: Content-Disposition: attachment; filename*=utf-8''"fianc%C3%A9e"
2173 However this is contrary to the examples in the email thread listed above.
2175 Developers report that IE7 (when it is configured for UTF-8 URL encoding,
2176 which is not the default in Asian countries), will accept::
2178 #4: Content-Disposition: attachment; filename=fianc%C3%A9e
2180 However, for maximum compatibility, Tahoe simply copies bytes from the URL
2181 into the response header, rather than enforcing the UTF-8 convention. This
2182 means it does not try to decode the filename from the URL argument, nor does
2183 it encode the filename into the response header.
2185 .. _RFC3986#2.1: https://tools.ietf.org/html/rfc3986#section-2.1
2186 .. _RFC2231#4: https://tools.ietf.org/html/rfc2231#section-4
2187 .. _some developers have reported: http://markmail.org/message/dsjyokgl7hv64ig3
2188 .. _RFC2616#19.5.1: https://tools.ietf.org/html/rfc2616#section-19.5.1