hgbook
view en/hook.tex @ 64:d12a199ed472
Update hook reference.
| author | Bryan O'Sullivan <bos@serpentine.com> |
|---|---|
| date | Fri Aug 04 13:43:26 2006 -0700 (2006-08-04) |
| parents | a00b562b4598 |
| children | 0707489b90fd |
line source
1 \chapter{Handling repository events with hooks}
2 \label{chap:hook}
4 Mercurial offers a powerful mechanism to let you perform automated
5 actions in response to events that occur in a repository. In some
6 cases, you can even control Mercurial's response to those events.
8 The name Mercurial uses for one of these actions is a \emph{hook}.
9 Hooks are called ``triggers'' in some revision control systems, but
10 the two names refer to the same idea.
12 \section{An overview of hooks in Mercurial}
14 Here is a brief list of the hooks that Mercurial supports. We will
15 revisit each of these hooks in more detail later, in
16 section~\ref{sec:hook:ref}.
18 \begin{itemize}
19 \item[\small\hook{changegroup}] This is run after a group of
20 changesets has been brought into the repository from elsewhere.
21 \item[\small\hook{commit}] This is run after a new changeset has been
22 created in the local repository.
23 \item[\small\hook{incoming}] This is run once for each new changeset
24 that is brought into the repository from elsewhere. Notice the
25 difference from \hook{changegroup}, which is run once per
26 \emph{group} of changesets brought in.
27 \item[\small\hook{outgoing}] This is run after a group of changesets
28 has been transmitted from this repository.
29 \item[\small\hook{prechangegroup}] This is run before starting to
30 bring a group of changesets into the repository.
31 \item[\small\hook{precommit}] Controlling. This is run before starting
32 a commit.
33 \item[\small\hook{preoutgoing}] Controlling. This is run before
34 starting to transmit a group of changesets from this repository.
35 \item[\small\hook{pretag}] Controlling. This is run before creating a tag.
36 \item[\small\hook{pretxnchangegroup}] Controlling. This is run after a
37 group of changesets has been brought into the local repository from
38 another, but before the transaction completes that will make the
39 changes permanent in the repository.
40 \item[\small\hook{pretxncommit}] Controlling. This is run after a new
41 changeset has been created in the local repository, but before the
42 transaction completes that will make it permanent.
43 \item[\small\hook{preupdate}] Controlling. This is run before starting
44 an update or merge of the working directory.
45 \item[\small\hook{tag}] This is run after a tag is created.
46 \item[\small\hook{update}] This is run after an update or merge of the
47 working directory has finished.
48 \end{itemize}
49 Each of the hooks whose description begins with the word
50 ``Controlling'' has the ability to determine whether an activity can
51 proceed. If the hook succeeds, the activity may proceed; if it fails,
52 the activity is either not permitted or undone, depending on the hook.
54 \section{Hooks and security}
56 \subsection{Hooks are run with your privileges}
58 When you run a Mercurial command in a repository, and the command
59 causes a hook to run, that hook runs on \emph{your} system, under
60 \emph{your} user account, with \emph{your} privilege level. Since
61 hooks are arbitrary pieces of executable code, you should treat them
62 with an appropriate level of suspicion. Do not install a hook unless
63 you are confident that you know who created it and what it does.
65 In some cases, you may be exposed to hooks that you did not install
66 yourself. If you work with Mercurial on an unfamiliar system,
67 Mercurial will run hooks defined in that system's global \hgrc\ file.
69 If you are working with a repository owned by another user, Mercurial
70 can run hooks defined in that user's repository, but it will still run
71 them as ``you''. For example, if you \hgcmd{pull} from that
72 repository, and its \sfilename{.hg/hgrc} defines a local
73 \hook{outgoing} hook, that hook will run under your user account, even
74 though you don't own that repository.
76 \begin{note}
77 This only applies if you are pulling from a repository on a local or
78 network filesystem. If you're pulling over http or ssh, any
79 \hook{outgoing} hook will run under whatever account is executing
80 the server process, on the server.
81 \end{note}
83 XXX To see what hooks are defined in a repository, use the
84 \hgcmdargs{config}{hooks} command. If you are working in one
85 repository, but talking to another that you do not own (e.g.~using
86 \hgcmd{pull} or \hgcmd{incoming}), remember that it is the other
87 repository's hooks you should be checking, not your own.
89 \subsection{Hooks do not propagate}
91 In Mercurial, hooks are not revision controlled, and do not propagate
92 when you clone, or pull from, a repository. The reason for this is
93 simple: a hook is a completely arbitrary piece of executable code. It
94 runs under your user identity, with your privilege level, on your
95 machine.
97 It would be extremely reckless for any distributed revision control
98 system to implement revision-controlled hooks, as this would offer an
99 easily exploitable way to subvert the accounts of users of the
100 revision control system.
102 Since Mercurial does not propagate hooks, if you are collaborating
103 with other people on a common project, you should not assume that they
104 are using the same Mercurial hooks as you are, or that theirs are
105 correctly configured. You should document the hooks you expect people
106 to use.
108 In a corporate intranet, this is somewhat easier to control, as you
109 can for example provide a ``standard'' installation of Mercurial on an
110 NFS filesystem, and use a site-wide \hgrc\ file to define hooks that
111 all users will see. However, this too has its limits; see below.
113 \subsection{Hooks can be overridden}
115 Mercurial allows you to override a hook definition by redefining the
116 hook. You can disable it by setting its value to the empty string, or
117 change its behaviour as you wish.
119 If you deploy a system-~or site-wide \hgrc\ file that defines some
120 hooks, you should thus understand that your users can disable or
121 override those hooks.
123 \subsection{Ensuring that critical hooks are run}
125 Sometimes you may want to enforce a policy that you do not want others
126 to be able to work around. For example, you may have a requirement
127 that every changeset must pass a rigorous set of tests. Defining this
128 requirement via a hook in a site-wide \hgrc\ won't work for remote
129 users on laptops, and of course local users can subvert it at will by
130 overriding the hook.
132 Instead, you can set up your policies for use of Mercurial so that
133 people are expected to propagate changes through a well-known
134 ``canonical'' server that you have locked down and configured
135 appropriately.
137 One way to do this is via a combination of social engineering and
138 technology. Set up a restricted-access account; users can push
139 changes over the network to repositories managed by this account, but
140 they cannot log into the account and run normal shell commands. In
141 this scenario, a user can commit a changeset that contains any old
142 garbage they want.
144 When someone pushes a changeset to the server that everyone pulls
145 from, the server will test the changeset before it accepts it as
146 permanent, and reject it if it fails to pass the test suite. If
147 people only pull changes from this filtering server, it will serve to
148 ensure that all changes that people pull have been automatically
149 vetted.
151 \section{Using hooks with shared access to a repository}
153 If you want to use hooks to so some automated work in a repository
154 that a number of people have shared access to, you need to be careful
155 in how you do this.
157 Mercurial only locks a repository when it is writing to the
158 repository, and only the parts of Mercurial that write to the
159 repository pay attention to locks. Write locks are necessary to
160 prevent multiple simultaneous writers from scribbling on each other's
161 work, corrupting the repository.
163 Because Mercurial is careful with the order in which it reads and
164 writes data, it does not need to acquire a lock when it wants to read
165 data from the repository. The parts of Mercurial that read from the
166 repository never pay attention to locks. This lockless reading scheme
167 greatly increases performance and concurrency.
169 With great performance comes a trade-off, though, one which has the
170 potential to cause you trouble unless you're aware of it. To describe
171 this requires a little detail about how Mercurial adds changesets to a
172 repository and reads those changes.
174 When Mercurial \emph{writes} metadata, it writes it straight into the
175 destination file. It writes file data first, then manifest data
176 (which contains pointers to the new file data), then changelog data
177 (which contains pointers to the new manifest data). Before the first
178 write to each file, it stores a record of where the end of the file
179 was in its transaction log. If the transaction must be rolled back,
180 Mercurial simply truncates each file back to the size it was before the
181 transaction began.
183 When Mercurial \emph{reads} metadata, it reads the changelog first,
184 then everything else. Since a reader will only access parts of the
185 manifest or file metadata that it can see in the changelog, it can
186 never see partially written data.
188 Some controlling hooks (\hook{pretxncommit} and
189 \hook{pretxnchangegroup}) run when a transaction is almost complete.
190 All of the metadata has been written, but Mercurial can still roll the
191 transaction back and cause the newly-written data to disappear.
193 If one of these hooks runs for long, it opens a window in which a
194 reader can see the metadata for changesets that are, strictly
195 speaking, not yet permanent. The longer the hook runs, the bigger the
196 window.
198 A good use for the \hook{pretxnchangegroup} hook would be to
199 automatically build and test incoming changes before they are accepted
200 into the repository, so that you can guarantee that nobody can push
201 changes to this repository that ``break the build''. But if a client
202 can pull changes while they're being tested, the usefulness of the
203 test is zero; someone can pull untested changes.
205 The safest answer to this challenge is to set up such a ``gatekeeper''
206 repository as \emph{unidirectional}. It can take changes pushed in
207 from the outside, but nobody can pull changes from it. Use the
208 \hook{preoutgoing} hook to lock it down. Configure a
209 \hook{changegroup} hook so that if a build or test succeeds, the hook
210 will push the new changes out to another repository that people
211 \emph{can} pull from.
213 \section{A short tutorial on using hooks}
214 \label{sec:hook:simple}
216 It is easy to write a Mercurial hook. Let's start with a hook that
217 runs when you finish a \hgcmd{commit}, and simply prints the hash of
218 the changeset you just created. The hook is called \hook{commit}.
220 \begin{figure}[ht]
221 \interaction{hook.simple.init}
222 \caption{A simple hook that runs when a changeset is committed}
223 \label{ex:hook:init}
224 \end{figure}
226 All hooks follow the pattern in example~\ref{ex:hook:init}. You add
227 an entry to the \rcsection{hooks} section of your \hgrc\. On the left
228 is the name of the event to trigger on; on the right is the action to
229 take. As you can see, you can run an arbitrary shell command in a
230 hook. Mercurial passes extra information to the hook using
231 environment variables (look for \envar{HG\_NODE} in the example).
233 \subsection{Performing multiple actions per event}
235 Quite often, you will want to define more than one hook for a
236 particular kind of event, as shown in example~\ref{ex:hook:ext}.
237 Mercurial lets you do this by adding an \emph{extension} to the end of
238 a hook's name. You extend a hook's name by giving the name of the
239 hook, followed by a full stop (the ``\texttt{.}'' character), followed
240 by some more text of your choosing. For example, Mercurial will run
241 both \texttt{commit.foo} and \texttt{commit.bar} when the
242 \texttt{commit} event occurs.
244 \begin{figure}[ht]
245 \interaction{hook.simple.ext}
246 \caption{Defining a second \hook{commit} hook}
247 \label{ex:hook:ext}
248 \end{figure}
250 To give a well-defined order of execution when there are multiple
251 hooks defined for an event, Mercurial sorts hooks by extension, and
252 executes the hook commands in this sorted order. In the above
253 example, it will execute \texttt{commit.bar} before
254 \texttt{commit.foo}, and \texttt{commit} before both.
256 It is a good idea to use a somewhat descriptive extension when you
257 define a new hook. This will help you to remember what the hook was
258 for. If the hook fails, you'll get an error message that contains the
259 hook name and extension, so using a descriptive extension could give
260 you an immediate hint as to why the hook failed (see
261 section~\ref{sec:hook:perm} for an example).
263 \subsection{Controlling whether an activity can proceed}
264 \label{sec:hook:perm}
266 In our earlier examples, we used the \hook{commit} hook, which is
267 run after a commit has completed. This is one of several Mercurial
268 hooks that run after an activity finishes. Such hooks have no way of
269 influencing the activity itself.
271 Mercurial defines a number of events that occur before an activity
272 starts; or after it starts, but before it finishes. Hooks that
273 trigger on these events have the added ability to choose whether the
274 activity can continue, or will abort.
276 The \hook{pretxncommit} hook runs after a commit has all but
277 completed. In other words, the metadata representing the changeset
278 has been written out to disk, but the transaction has not yet been
279 allowed to complete. The \hook{pretxncommit} hook has the ability to
280 decide whether the transaction can complete, or must be rolled back.
282 If the \hook{pretxncommit} hook exits with a status code of zero, the
283 transaction is allowed to complete; the commit finishes; and the
284 \hook{commit} hook is run. If the \hook{pretxncommit} hook exits with
285 a non-zero status code, the transaction is rolled back; the metadata
286 representing the changeset is erased; and the \hook{commit} hook is
287 not run.
289 \begin{figure}[ht]
290 \interaction{hook.simple.pretxncommit}
291 \caption{Using the \hook{pretxncommit} hook to control commits}
292 \label{ex:hook:pretxncommit}
293 \end{figure}
295 The hook in example~\ref{ex:hook:pretxncommit} checks that a commit
296 comment contains a bug ID. If it does, the commit can complete. If
297 not, the commit is rolled back.
299 \section{Writing your own hooks}
301 When you are writing a hook, you might find it useful to run Mercurial
302 either with the \hggopt{-v} option, or the \rcitem{ui}{verbose} config
303 item set to ``true''. When you do so, Mercurial will print a message
304 before it calls each hook.
306 \subsection{Choosing how your hook should run}
307 \label{sec:hook:lang}
309 You can write a hook either as a normal program---typically a shell
310 script---or as a Python function that is executed within the Mercurial
311 process.
313 Writing a hook as an external program has the advantage that it
314 requires no knowledge of Mercurial's internals. You can call normal
315 Mercurial commands to get any added information you need. The
316 trade-off is that external hooks are slower than in-process hooks.
318 An in-process Python hook has complete access to the Mercurial API,
319 and does not ``shell out'' to another process, so it is inherently
320 faster than an external hook. It is also easier to obtain much of the
321 information that a hook requires by using the Mercurial API than by
322 running Mercurial commands.
324 If you are comfortable with Python, or require high performance,
325 writing your hooks in Python may be a good choice. However, when you
326 have a straightforward hook to write and you don't need to care about
327 performance (probably the majority of hooks), a shell script is
328 perfectly fine.
330 \subsection{Hook parameters}
331 \label{sec:hook:param}
333 Mercurial calls each hook with a set of well-defined parameters. In
334 Python, a parameter is passed as a keyword argument to your hook
335 function. For an external program, a parameter is passed as an
336 environment variable.
338 Whether your hook is written in Python or as a shell script, the
339 hook-specific parameter names and values will be the same. A boolean
340 parameter will be represented as a boolean value in Python, but as the
341 number 1 (for ``true'') or 0 (for ``false'') as an environment
342 variable for an external hook. If a hook parameter is named
343 \texttt{foo}, the keyword argument for a Python hook will also be
344 named \texttt{foo}, while the environment variable for an external
345 hook will be named \texttt{HG\_FOO}.
347 \subsection{Hook return values and activity control}
349 A hook that executes successfully must exit with a status of zero if
350 external, or return boolean ``false'' if in-process. Failure is
351 indicated with a non-zero exit status from an external hook, or an
352 in-process hook returning boolean ``true''. If an in-process hook
353 raises an exception, the hook is considered to have failed.
355 For a hook that controls whether an activity can proceed, zero/false
356 means ``allow'', while non-zero/true/exception means ``deny''.
358 \subsection{Writing an external hook}
360 When you define an external hook in your \hgrc\ and the hook is run,
361 its value is passed to your shell, which interprets it. This means
362 that you can use normal shell constructs in the body of the hook.
364 An executable hook is always run with its current directory set to a
365 repository's root directory.
367 Each hook parameter is passed in as an environment variable; the name
368 is upper-cased, and prefixed with the string ``\texttt{HG\_}''.
370 With the exception of hook parameters, Mercurial does not set or
371 modify any environment variables when running a hook. This is useful
372 to remember if you are writing a site-wide hook that may be run by a
373 number of different users with differing environment variables set.
374 In multi-user situations, you should not rely on environment variables
375 being set to the values you have in your environment when testing the
376 hook.
378 \subsection{Telling Mercurial to use an in-process hook}
380 The \hgrc\ syntax for defining an in-process hook is slightly
381 different than for an executable hook. The value of the hook must
382 start with the text ``\texttt{python:}'', and continue with the
383 fully-qualified name of a callable object to use as the hook's value.
385 The module in which a hook lives is automatically imported when a hook
386 is run. So long as you have the module name and \envar{PYTHONPATH}
387 right, it should ``just work''.
389 The following \hgrc\ example snippet illustrates the syntax and
390 meaning of the notions we just described.
391 \begin{codesample2}
392 [hooks]
393 commit.example = python:mymodule.submodule.myhook
394 \end{codesample2}
395 When Mercurial runs the \texttt{commit.example} hook, it imports
396 \texttt{mymodule.submodule}, looks for the callable object named
397 \texttt{myhook}, and calls it.
399 \subsection{Writing an in-process hook}
401 The simplest in-process hook does nothing, but illustrates the basic
402 shape of the hook API:
403 \begin{codesample2}
404 def myhook(ui, repo, **kwargs):
405 pass
406 \end{codesample2}
407 The first argument to a Python hook is always a
408 \pymodclass{mercurial.ui}{ui} object. The second is a repository object;
409 at the moment, it is always an instance of
410 \pymodclass{mercurial.localrepo}{localrepository}. Following these two
411 arguments are other keyword arguments. Which ones are passed in
412 depends on the hook being called, but a hook can ignore arguments it
413 doesn't care about by dropping them into a keyword argument dict, as
414 with \texttt{**kwargs} above.
416 \section{Some hook examples}
418 \subsection{Writing meaningful commit messages}
420 It's hard to imagine a useful commit message being very short. The
421 simple \hook{pretxncommit} hook of figure~\ref{ex:hook:msglen.run}
422 will prevent you from committing a changeset with a message that is
423 less than ten bytes long.
425 \begin{figure}[ht]
426 \interaction{hook.msglen.run}
427 \caption{A hook that forbids overly short commit messages}
428 \label{ex:hook:msglen.run}
429 \end{figure}
431 \subsection{Checking for trailing whitespace}
433 An interesting use of a commit-related hook is to help you to write
434 cleaner code. A simple example of ``cleaner code'' is the dictum that
435 a change should not add any new lines of text that contain ``trailing
436 whitespace''. Trailing whitespace is a series of space and tab
437 characters at the end of a line of text. In most cases, trailing
438 whitespace is unnecessary, invisible noise, but it is occasionally
439 problematic, and people often prefer to get rid of it.
441 You can use either the \hook{precommit} or \hook{pretxncommit} hook to
442 tell whether you have a trailing whitespace problem. If you use the
443 \hook{precommit} hook, the hook will not know which files you are
444 committing, so it will have to check every modified file in the
445 repository for trailing white space. If you want to commit a change
446 to just the file \filename{foo}, but the file \filename{bar} contains
447 trailing whitespace, doing a check in the \hook{precommit} hook will
448 prevent you from committing \filename{foo} due to the problem with
449 \filename{bar}. This doesn't seem right.
451 Should you choose the \hook{pretxncommit} hook, the check won't occur
452 until just before the transaction for the commit completes. This will
453 allow you to check for problems only the exact files that are being
454 committed. However, if you entered the commit message interactively
455 and the hook fails, the transaction will roll back; you'll have to
456 re-enter the commit message after you fix the trailing whitespace and
457 run \hgcmd{commit} again.
459 \begin{figure}[ht]
460 \interaction{hook.ws.simple}
461 \caption{A simple hook that checks for trailing whitespace}
462 \label{ex:hook:ws.simple}
463 \end{figure}
465 Figure~\ref{ex:hook:ws.simple} introduces a simple \hook{pretxncommit}
466 hook that checks for trailing whitespace. This hook is short, but not
467 very helpful. It exits with an error status if a change adds a line
468 with trailing whitespace to any file, but does not print any
469 information that might help us to identify the offending file or
470 line. It also has the nice property of not paying attention to
471 unmodified lines; only lines that introduce new trailing whitespace
472 cause problems.
474 \begin{figure}[ht]
475 \interaction{hook.ws.better}
476 \caption{A better trailing whitespace hook}
477 \label{ex:hook:ws.better}
478 \end{figure}
480 The example of figure~\ref{ex:hook:ws.better} is much more complex,
481 but also more useful. It parses a unified diff to see if any lines
482 add trailing whitespace, and prints the name of the file and the line
483 number of each such occurrence. Even better, if the change adds
484 trailing whitespace, this hook saves the commit comment and prints the
485 name of the save file before exiting and telling Mercurial to roll the
486 transaction back, so you can use
487 \hgcmdargs{commit}{\hgopt{commit}{-l}~\emph{filename}} to reuse the
488 saved commit message once you've corrected the problem.
490 As a final aside, note in figure~\ref{ex:hook:ws.better} the use of
491 \command{perl}'s in-place editing feature to get rid of trailing
492 whitespace from a file. This is concise and useful enough that I will
493 reproduce it here.
494 \begin{codesample2}
495 perl -pi -e 's,\\s+\$,,' filename
496 \end{codesample2}
498 \section{Bundled hooks}
500 Mercurial ships with several bundled hooks. You can find them in the
501 \dirname{hgext} directory of a Mercurial source tree. If you are
502 using a Mercurial binary package, the hooks will be located in the
503 \dirname{hgext} directory of wherever your package installer put
504 Mercurial.
506 \subsection{\hgext{acl}---access control for parts of a repository}
508 The \hgext{acl} extension lets you control which remote users are
509 allowed to push changesets to a networked server. You can protect any
510 portion of a repository (including the entire repo), so that a
511 specific remote user can push changes that do not affect the protected
512 portion.
514 This extension implements access control based on the identity of the
515 user performing a push, \emph{not} on who committed the changesets
516 they're pushing. It makes sense to use this hook only if you have a
517 locked-down server environment that authenticates remote users, and
518 you want to be sure that only specific users are allowed to push
519 changes to that server.
521 \subsubsection{Configuring the \hook{acl} hook}
523 In order to manage incoming changesets, the \hgext{acl} hook must be
524 used as a \hook{pretxnchangegroup} hook. This lets it see which files
525 are modified by each incoming changeset, and roll back a group of
526 changesets if they modify ``forbidden'' files. Example:
527 \begin{codesample2}
528 [hooks]
529 pretxnchangegroup.acl = python:hgext.acl.hook
530 \end{codesample2}
532 The \hgext{acl} extension is configured using three sections.
534 The \rcsection{acl} section has only one entry, \rcitem{acl}{sources},
535 which lists the sources of incoming changesets that the hook should
536 pay attention to. You don't normally need to configure this section.
537 \begin{itemize}
538 \item[\rcitem{acl}{serve}] Control incoming changesets that are arriving
539 from a remote repository over http or ssh. This is the default
540 value of \rcitem{acl}{sources}, and usually the only setting you'll
541 need for this configuration item.
542 \item[\rcitem{acl}{pull}] Control incoming changesets that are
543 arriving via a pull from a local repository.
544 \item[\rcitem{acl}{push}] Control incoming changesets that are
545 arriving via a push from a local repository.
546 \item[\rcitem{acl}{bundle}] Control incoming changesets that are
547 arriving from another repository via a bundle.
548 \end{itemize}
550 The \rcsection{acl.allow} section controls the users that are allowed to
551 add changesets to the repository. If this section is not present, all
552 users that are not explicitly denied are allowed. If this section is
553 present, all users that are not explicitly allowed are denied (so an
554 empty section means that all users are denied).
556 The \rcsection{acl.deny} section determines which users are denied
557 from adding changesets to the repository. If this section is not
558 present or is empty, no users are denied.
560 The syntaxes for the \rcsection{acl.allow} and \rcsection{acl.deny}
561 sections are identical. On the left of each entry is a glob pattern
562 that matches files or directories, relative to the root of the
563 repository; on the right, a user name.
565 In the following example, the user \texttt{docwriter} can only push
566 changes to the \dirname{docs} subtree of the repository, while
567 \texttt{intern} can push changes to any file or directory except
568 \dirname{source/sensitive}.
569 \begin{codesample2}
570 [acl.allow]
571 docs/** = docwriter
573 [acl.deny]
574 source/sensitive/** = intern
575 \end{codesample2}
577 \subsubsection{Testing and troubleshooting}
579 If you want to test the \hgext{acl} hook, run it with Mercurial's
580 debugging output enabled. Since you'll probably be running it on a
581 server where it's not convenient (or sometimes possible) to pass in
582 the \hggopt{--debug} option, don't forget that you can enable
583 debugging output in your \hgrc:
584 \begin{codesample2}
585 [ui]
586 debug = true
587 \end{codesample2}
588 With this enabled, the \hgext{acl} hook will print enough information
589 to let you figure out why it is allowing or forbidding pushes from
590 specific users.
592 \subsection{\hgext{bugzilla}---integration with Bugzilla}
594 The \hgext{bugzilla} extension adds a comment to a Bugzilla bug
595 whenever it finds a reference to that bug ID in a commit comment. You
596 can install this hook on a shared server, so that any time a remote
597 user pushes changes to this server, the hook gets run.
599 It adds a comment to the bug that looks like this (you can configure
600 the contents of the comment---see below):
601 \begin{codesample2}
602 Changeset aad8b264143a, made by Joe User <joe.user@domain.com> in
603 the frobnitz repository, refers to this bug.
605 For complete details, see
606 http://hg.domain.com/frobnitz?cmd=changeset;node=aad8b264143a
608 Changeset description:
609 Fix bug 10483 by guarding against some NULL pointers
610 \end{codesample2}
611 The value of this hook is that it automates the process of updating a
612 bug any time a changeset refers to it. If you configure the hook
613 properly, it makes it easy for people to browse straight from a
614 Bugzilla bug to a changeset that refers to that bug.
616 You can use the code in this hook as a starting point for some more
617 exotic Bugzilla integration recipes. Here are a few possibilities:
618 \begin{itemize}
619 \item Require that every changeset pushed to the server have a valid
620 bug~ID in its commit comment. In this case, you'd want to configure
621 the hook as a \hook{pretxncommit} hook. This would allow the hook
622 to reject changes that didn't contain bug IDs.
623 \item Allow incoming changesets to automatically modify the
624 \emph{state} of a bug, as well as simply adding a comment. For
625 example, the hook could recognise the string ``fixed bug 31337'' as
626 indicating that it should update the state of bug 31337 to
627 ``requires testing''.
628 \end{itemize}
630 \subsubsection{Configuring the \hook{bugzilla} hook}
631 \label{sec:hook:bugzilla:config}
633 You should configure this hook in your server's \hgrc\ as an
634 \hook{incoming} hook, for example as follows:
635 \begin{codesample2}
636 [hooks]
637 incoming.bugzilla = python:hgext.bugzilla.hook
638 \end{codesample2}
640 Because of the specialised nature of this hook, and because Bugzilla
641 was not written with this kind of integration in mind, configuring
642 this hook is a somewhat involved process.
644 Before you begin, you must install the MySQL bindings for Python on
645 the host(s) where you'll be running the hook. If this is not
646 available as a binary package for your system, you can download it
647 from~\cite{web:mysql-python}.
649 Configuration information for this hook lives in the
650 \rcsection{bugzilla} section of your \hgrc.
651 \begin{itemize}
652 \item[\rcitem{bugzilla}{version}] The version of Bugzilla installed on
653 the server. The database schema that Bugzilla uses changes
654 occasionally, so this hook has to know exactly which schema to use.
655 At the moment, the only version supported is \texttt{2.16}.
656 \item[\rcitem{bugzilla}{host}] The hostname of the MySQL server that
657 stores your Bugzilla data. The database must be configured to allow
658 connections from whatever host you are running the \hook{bugzilla}
659 hook on.
660 \item[\rcitem{bugzilla}{user}] The username with which to connect to
661 the MySQL server. The database must be configured to allow this
662 user to connect from whatever host you are running the
663 \hook{bugzilla} hook on. This user must be able to access and
664 modify Bugzilla tables. The default value of this item is
665 \texttt{bugs}, which is the standard name of the Bugzilla user in a
666 MySQL database.
667 \item[\rcitem{bugzilla}{password}] The MySQL password for the user you
668 configured above. This is stored as plain text, so you should make
669 sure that unauthorised users cannot read the \hgrc\ file where you
670 store this information.
671 \item[\rcitem{bugzilla}{db}] The name of the Bugzilla database on the
672 MySQL server. The default value of this item is \texttt{bugs},
673 which is the standard name of the MySQL database where Bugzilla
674 stores its data.
675 \item[\rcitem{bugzilla}{notify}] If you want Bugzilla to send out a
676 notification email to subscribers after this hook has added a
677 comment to a bug, you will need this hook to run a command whenever
678 it updates the database. The command to run depends on where you
679 have installed Bugzilla, but it will typically look something like
680 this, if you have Bugzilla installed in
681 \dirname{/var/www/html/bugzilla}:
682 \begin{codesample4}
683 cd /var/www/html/bugzilla && ./processmail %s nobody@nowhere.com
684 \end{codesample4}
685 The Bugzilla \texttt{processmail} program expects to be given a
686 bug~ID (the hook replaces ``\texttt{\%s}'' with the bug~ID) and an
687 email address. It also expects to be able to write to some files in
688 the directory that it runs in. If Bugzilla and this hook are not
689 installed on the same machine, you will need to find a way to run
690 \texttt{processmail} on the server where Bugzilla is installed.
691 \end{itemize}
693 \subsubsection{Mapping committer names to Bugzilla user names}
695 By default, the \hgext{bugzilla} hook tries to use the email address
696 of a changeset's committer as the Bugzilla user name with which to
697 update a bug. If this does not suit your needs, you can map committer
698 email addresses to Bugzilla user names using a \rcsection{usermap}
699 section.
701 Each item in the \rcsection{usermap} section contains an email address
702 on the left, and a Bugzilla user name on the right.
703 \begin{codesample2}
704 [usermap]
705 jane.user@example.com = jane
706 \end{codesample2}
707 You can either keep the \rcsection{usermap} data in a normal \hgrc, or
708 tell the \hgext{bugzilla} hook to read the information from an
709 external \filename{usermap} file. In the latter case, you can store
710 \filename{usermap} data by itself in (for example) a user-modifiable
711 repository. This makes it possible to let your users maintain their
712 own \rcitem{bugzilla}{usermap} entries. The main \hgrc\ file might
713 look like this:
714 \begin{codesample2}
715 # regular hgrc file refers to external usermap file
716 [bugzilla]
717 usermap = /home/hg/repos/userdata/bugzilla-usermap.conf
718 \end{codesample2}
719 While the \filename{usermap} file that it refers to might look like
720 this:
721 \begin{codesample2}
722 # bugzilla-usermap.conf - inside a hg repository
723 [usermap]
724 stephanie@example.com = steph
725 \end{codesample2}
727 \subsubsection{Configuring the text that gets added to a bug}
729 You can configure the text that this hook adds as a comment; you
730 specify it in the form of a Mercurial template. Several \hgrc\
731 entries (still in the \rcsection{bugzilla} section) control this
732 behaviour.
733 \begin{itemize}
734 \item[\texttt{strip}] The number of leading path elements to strip
735 from a repository's path name to construct a partial path for a URL.
736 For example, if the repositories on your server live under
737 \dirname{/home/hg/repos}, and you have a repository whose path is
738 \dirname{/home/hg/repos/app/tests}, then setting \texttt{strip} to
739 \texttt{4} will give a partial path of \dirname{app/tests}. The
740 hook will make this partial path available when expanding a
741 template, as \texttt{webroot}.
742 \item[\texttt{template}] The text of the template to use. In addition
743 to the usual changeset-related variables, this template can use
744 \texttt{hgweb} (the value of the \texttt{hgweb} configuration item
745 above) and \texttt{webroot} (the path constructed using
746 \texttt{strip} above).
747 \end{itemize}
749 In addition, you can add a \rcitem{web}{baseurl} item to the
750 \rcsection{web} section of your \hgrc. The \hgext{bugzilla} hook will
751 make this available when expanding a template, as the base string to
752 use when constructing a URL that will let users browse from a Bugzilla
753 comment to view a changeset. Example:
754 \begin{codesample2}
755 [web]
756 baseurl = http://hg.domain.com/
757 \end{codesample2}
759 Here is an example set of \hgext{bugzilla} hook config information.
760 \begin{codesample2}
761 [bugzilla]
762 host = bugzilla.example.com
763 password = mypassword
764 version = 2.16
765 # server-side repos live in /home/hg/repos, so strip 4 leading
766 # separators
767 strip = 4
768 hgweb = http://hg.example.com/
769 usermap = /home/hg/repos/notify/bugzilla.conf
770 template = Changeset \{node|short\}, made by \{author\} in the \{webroot\}
771 repo, refers to this bug.\\nFor complete details, see
772 \{hgweb\}\{webroot\}?cmd=changeset;node=\{node|short\}\\nChangeset
773 description:\\n\\t\{desc|tabindent\}
774 \end{codesample2}
776 \subsubsection{Testing and troubleshooting}
778 The most common problems with configuring the \hgext{bugzilla} hook
779 relate to running Bugzilla's \filename{processmail} script and mapping
780 committer names to user names.
782 Recall from section~\ref{sec:hook:bugzilla:config} above that the user
783 that runs the Mercurial process on the server is also the one that
784 will run the \filename{processmail} script. The
785 \filename{processmail} script sometimes causes Bugzilla to write to
786 files in its configuration directory, and Bugzilla's configuration
787 files are usually owned by the user that your web server runs under.
789 You can cause \filename{processmail} to be run with the suitable
790 user's identity using the \command{sudo} command. Here is an example
791 entry for a \filename{sudoers} file.
792 \begin{codesample2}
793 hg_user = (httpd_user) NOPASSWD: /var/www/html/bugzilla/processmail-wrapper %s
794 \end{codesample2}
795 This allows the \texttt{hg\_user} user to run a
796 \filename{processmail-wrapper} program under the identity of
797 \texttt{httpd\_user}.
799 This indirection through a wrapper script is necessary, because
800 \filename{processmail} expects to be run with its current directory
801 set to wherever you installed Bugzilla; you can't specify that kind of
802 constraint in a \filename{sudoers} file. The contents of the wrapper
803 script are simple:
804 \begin{codesample2}
805 #!/bin/sh
806 cd `dirname $0` && ./processmail "$1" nobody@example.com
807 \end{codesample2}
808 It doesn't seem to matter what email address you pass to
809 \filename{processmail}.
811 If your \rcsection{usermap} is not set up correctly, users will see an
812 error message from the \hgext{bugzilla} hook when they push changes
813 to the server. The error message will look like this:
814 \begin{codesample2}
815 cannot find bugzilla user id for john.q.public@example.com
816 \end{codesample2}
817 What this means is that the committer's address,
818 \texttt{john.q.public@example.com}, is not a valid Bugzilla user name,
819 nor does it have an entry in your \rcsection{usermap} that maps it to
820 a valid Bugzilla user name.
822 \subsection{\hgext{notify}---send email notifications}
824 Although Mercurial's built-in web server provides RSS feeds of changes
825 in every repository, many people prefer to receive change
826 notifications via email. The \hgext{notify} hook lets you send out
827 notifications to a set of email addresses whenever changesets arrive
828 that those subscribers are interested in.
830 As with the \hgext{bugzilla} hook, the \hgext{notify} hook is
831 template-driven, so you can customise the contents of the notification
832 messages that it sends.
834 By default, the \hgext{notify} hook includes a diff of every changeset
835 that it sends out; you can limit the size of the diff, or turn this
836 feature off entirely. It is useful for letting subscribers review
837 changes immediately, rather than clicking to follow a URL.
839 \subsubsection{Configuring the \hgext{notify} hook}
841 You can set up the \hgext{notify} hook to send one email message per
842 incoming changeset, or one per incoming group of changesets (all those
843 that arrived in a single pull or push).
844 \begin{codesample2}
845 [hooks]
846 # send one email per group of changes
847 changegroup.notify = python:hgext.notify.hook
848 # send one email per change
849 incoming.notify = python:hgext.notify.hook
850 \end{codesample2}
852 Configuration information for this hook lives in the
853 \rcsection{notify} section of a \hgrc\ file.
854 \begin{itemize}
855 \item[\rcitem{notify}{test}] By default, this hook does not send out
856 email at all; instead, it prints the message that it \emph{would}
857 send. Set this item to \texttt{false} to allow email to be sent.
858 The reason that sending of email is turned off by default is that it
859 takes several tries to configure this extension exactly as you would
860 like, and it would be bad form to spam subscribers with a number of
861 ``broken'' notifications while you debug your configuration.
862 \item[\rcitem{notify}{config}] The path to a configuration file that
863 contains subscription information. This is kept separate from the
864 main \hgrc\ so that you can maintain it in a repository of its own.
865 People can then clone that repository, update their subscriptions,
866 and push the changes back to your server.
867 \item[\rcitem{notify}{strip}] The number of leading path separator
868 characters to strip from a repository's path, when deciding whether
869 a repository has subscribers. For example, if the repositories on
870 your server live in \dirname{/home/hg/repos}, and \hgext{notify} is
871 considering a repository named \dirname{/home/hg/repos/shared/test},
872 setting \rcitem{notify}{strip} to \texttt{4} will cause
873 \hgext{notify} to trim the path it considers down to
874 \dirname{shared/test}, and it will match subscribers against that.
875 \item[\rcitem{notify}{template}] The template text to use when sending
876 messages. This specifies both the contents of the message header
877 and its body.
878 \item[\rcitem{notify}{maxdiff}] The maximum number of lines of diff
879 data to append to the end of a message. If a diff is longer than
880 this, it is truncated. By default, this is set to 300. Set this to
881 \texttt{0} to omit diffs from notification emails.
882 \item[\rcitem{notify}{sources}] A list of sources of changesets to
883 consider. This lets you limit \hgext{notify} to only sending out
884 email about changes that remote users pushed into this repository
885 via a server, for example. See section~\ref{sec:hook:sources} for
886 the sources you can specify here.
887 \end{itemize}
889 If you set the \rcitem{web}{baseurl} item in the \rcsection{web}
890 section, you can use it in a template; it will be available as
891 \texttt{webroot}.
893 Here is an example set of \hgext{notify} configuration information.
894 \begin{codesample2}
895 [notify]
896 # really send email
897 test = false
898 # subscriber data lives in the notify repo
899 config = /home/hg/repos/notify/notify.conf
900 # repos live in /home/hg/repos on server, so strip 4 "/" chars
901 strip = 4
902 template = X-Hg-Repo: \{webroot\}\\n\\\\
903 Subject: \{webroot\}: \{desc|firstline|strip\}\\n\\\\
904 From: \{author\}\\n\\\\
905 \\n\\\\
906 changeset \{node|short\} in \{root\}\\n\\\\
907 details: \{baseurl\}\{webroot\}?cmd=changeset;node=\{node|short\}\\n\\\\
908 description:\\n\\\\
909 \\t\{desc|tabindent|strip\}
911 [web]
912 baseurl = http://hg.example.com/
913 \end{codesample2}
915 This will produce a message that looks like the following:
916 \begin{codesample2}
917 X-Hg-Repo: tests/slave
918 Subject: tests/slave: Handle error case when slave has no buffers
919 Date: Wed, 2 Aug 2006 15:25:46 -0700 (PDT)
921 changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave
922 details: http://hg.example.com/tests/slave?cmd=changeset;node=3cba9bfe74b5
923 description:
924 Handle error case when slave has no buffers
925 diffs (54 lines):
927 diff -r 9d95df7cf2ad -r 3cba9bfe74b5 include/tests.h
928 --- a/include/tests.h Wed Aug 02 15:19:52 2006 -0700
929 +++ b/include/tests.h Wed Aug 02 15:25:26 2006 -0700
930 @@ -212,6 +212,15 @@ static __inline__ void test_headers(void *h)
931 [...snip...]
932 \end{codesample2}
934 \subsubsection{Testing and troubleshooting}
936 Do not forget that by default, the \hgext{notify} extension \emph{will
937 not send any mail} until you explicitly configure it to do so, by
938 setting \rcitem{notify}{test} to \texttt{false}. Until you do that,
939 it simply prints the message it \emph{would} send.
941 \section{Information for writers of hooks}
942 \label{sec:hook:ref}
944 \subsection{In-process hook execution}
946 An in-process hook is called with arguments of the following form:
947 \begin{codesample2}
948 def myhook(ui, repo, **kwargs):
949 pass
950 \end{codesample2}
951 The \texttt{ui} parameter is a \pymodclass{mercurial.ui}{ui} object.
952 The \texttt{repo} parameter is a
953 \pymodclass{mercurial.localrepo}{localrepository} object. The
954 names and values of the \texttt{**kwargs} parameters depend on the
955 hook being invoked, with the following common features:
956 \begin{itemize}
957 \item If a parameter is named \texttt{node} or
958 \texttt{parent\emph{N}}, it will contain a hexadecimal changeset ID.
959 The empty string is used to represent ``null changeset ID'' instead
960 of a string of zeroes.
961 \item If a parameter is named \texttt{url}, it will contain the URL of
962 a remote repository, if that can be determined.
963 \item Boolean-valued parameters are represented as Python
964 \texttt{bool} objects.
965 \end{itemize}
967 An in-process hook is called without a change to the process's working
968 directory (unlike external hooks, which are run in the root of the
969 repository). It must not change the process's working directory, or
970 it will cause any calls it makes into the Mercurial API to fail.
972 If a hook returns a boolean ``false'' value, it is considered to have
973 succeeded. If it returns a boolean ``true'' value or raises an
974 exception, it is considered to have failed. A useful way to think of
975 the calling convention is ``tell me if you fail''.
977 Note that changeset IDs are passed into Python hooks as hexadecimal
978 strings, not the binary hashes that Mercurial's APIs normally use. To
979 convert a hash from hex to binary, use the
980 \pymodfunc{mercurial.node}{bin} function.
982 \subsection{External hook execution}
984 An external hook is passed to the shell of the user running Mercurial.
985 Features of that shell, such as variable substitution and command
986 redirection, are available. The hook is run in the root directory of
987 the repository (unlike in-process hooks, which are run in the same
988 directory that Mercurial was run in).
990 Hook parameters are passed to the hook as environment variables. Each
991 environment variable's name is converted in upper case and prefixed
992 with the string ``\texttt{HG\_}''. For example, if the name of a
993 parameter is ``\texttt{node}'', the name of the environment variable
994 representing that parameter will be ``\texttt{HG\_NODE}''.
996 A boolean parameter is represented as the string ``\texttt{1}'' for
997 ``true'', ``\texttt{0}'' for ``false''. If an environment variable is
998 named \envar{HG\_NODE}, \envar{HG\_PARENT1} or \envar{HG\_PARENT2}, it
999 contains a changeset ID represented as a hexadecimal string. The
1000 empty string is used to represent ``null changeset ID'' instead of a
1001 string of zeroes. If an environment variable is named
1002 \envar{HG\_URL}, it will contain the URL of a remote repository, if
1003 that can be determined.
1005 If a hook exits with a status of zero, it is considered to have
1006 succeeded. If it exits with a non-zero status, it is considered to
1007 have failed.
1009 \subsection{Finding out where changesets come from}
1011 A hook that involves the transfer of changesets between a local
1012 repository and another may be able to find out information about the
1013 ``far side''. Mercurial knows \emph{how} changes are being
1014 transferred, and in many cases \emph{where} they are being transferred
1015 to or from.
1017 \subsubsection{Sources of changesets}
1018 \label{sec:hook:sources}
1020 Mercurial will tell a hook what means are, or were, used to transfer
1021 changesets between repositories. This is provided by Mercurial in a
1022 Python parameter named \texttt{source}, or an environment variable named
1023 \envar{HG\_SOURCE}.
1025 \begin{itemize}
1026 \item[\texttt{serve}] Changesets are transferred to or from a remote
1027 repository over http or ssh.
1028 \item[\texttt{pull}] Changesets are being transferred via a pull from
1029 one repository into another.
1030 \item[\texttt{push}] Changesets are being transferred via a push from
1031 one repository into another.
1032 \item[\texttt{bundle}] Changesets are being transferred to or from a
1033 bundle.
1034 \end{itemize}
1036 \subsubsection{Where changes are going---remote repository URLs}
1037 \label{sec:hook:url}
1039 When possible, Mercurial will tell a hook the location of the ``far
1040 side'' of an activity that transfers changeset data between
1041 repositories. This is provided by Mercurial in a Python parameter
1042 named \texttt{url}, or an environment variable named \envar{HG\_URL}.
1044 This information is not always known. If a hook is invoked in a
1045 repository that is being served via http or ssh, Mercurial cannot tell
1046 where the remote repository is, but it may know where the client is
1047 connecting from. In such cases, the URL will take one of the
1048 following forms:
1049 \begin{itemize}
1050 \item \texttt{remote:ssh:\emph{ip-address}}---remote ssh client, at
1051 the given IP address.
1052 \item \texttt{remote:http:\emph{ip-address}}---remote http client, at
1053 the given IP address. If the client is using SSL, this will be of
1054 the form \texttt{remote:https:\emph{ip-address}}.
1055 \item Empty---no information could be discovered about the remote
1056 client.
1057 \end{itemize}
1059 \section{Hook reference}
1061 \subsection{\hook{changegroup}---after remote changesets added}
1062 \label{sec:hook:changegroup}
1064 This hook is run after a group of pre-existing changesets has been
1065 added to the repository, for example via a \hgcmd{pull} or
1066 \hgcmd{unbundle}. This hook is run once per operation that added one
1067 or more changesets. This is in contrast to the \hook{incoming} hook,
1068 which is run once per changeset, regardless of whether the changesets
1069 arrive in a group.
1071 Some possible uses for this hook include kicking off an automated
1072 build or test of the added changesets, updating a bug database, or
1073 notifying subscribers that a repository contains new changes.
1075 Parameters to this hook:
1076 \begin{itemize}
1077 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1078 changeset in the group that was added. All changesets between this
1079 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
1080 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
1081 \item[\texttt{source}] A string. The source of these changes. See
1082 section~\ref{sec:hook:sources} for details.
1083 \item[\texttt{url}] A URL. The location of the remote repository, if
1084 known. See section~\ref{sec:hook:url} for more information.
1085 \end{itemize}
1087 See also: \hook{incoming} (section~\ref{sec:hook:incoming}),
1088 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}),
1089 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1091 \subsection{\hook{commit}---after a new changeset is created}
1092 \label{sec:hook:commit}
1094 This hook is run after a new changeset has been created.
1096 Parameters to this hook:
1097 \begin{itemize}
1098 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
1099 committed changeset.
1100 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1101 parent of the newly committed changeset.
1102 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1103 parent of the newly committed changeset.
1104 \end{itemize}
1106 See also: \hook{precommit} (section~\ref{sec:hook:precommit}),
1107 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
1109 \subsection{\hook{incoming}---after one remote changeset is added}
1110 \label{sec:hook:incoming}
1112 This hook is run after a pre-existing changeset has been added to the
1113 repository, for example via a \hgcmd{push}. If a group of changesets
1114 was added in a single operation, this hook is called once for each
1115 added changeset.
1117 You can use this hook for the same purposes as the \hook{changegroup}
1118 hook (section~\ref{sec:hook:changegroup}); it's simply more convenient
1119 sometimes to run a hook once per group of changesets, while other
1120 times it's handier once per changeset.
1122 Parameters to this hook:
1123 \begin{itemize}
1124 \item[\texttt{node}] A changeset ID. The ID of the newly added
1125 changeset.
1126 \item[\texttt{source}] A string. The source of these changes. See
1127 section~\ref{sec:hook:sources} for details.
1128 \item[\texttt{url}] A URL. The location of the remote repository, if
1129 known. See section~\ref{sec:hook:url} for more information.
1130 \end{itemize}
1132 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}) \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}), \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1134 \subsection{\hook{outgoing}---after changesets are propagated}
1135 \label{sec:hook:outgoing}
1137 This hook is run after a group of changesets has been propagated out
1138 of this repository, for example by a \hgcmd{push} or \hgcmd{bundle}
1139 command.
1141 One possible use for this hook is to notify administrators that
1142 changes have been pulled.
1144 Parameters to this hook:
1145 \begin{itemize}
1146 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1147 changeset of the group that was sent.
1148 \item[\texttt{source}] A string. The source of the of the operation
1149 (see section~\ref{sec:hook:sources}). If a remote client pulled
1150 changes from this repository, \texttt{source} will be
1151 \texttt{serve}. If the client that obtained changes from this
1152 repository was local, \texttt{source} will be \texttt{bundle},
1153 \texttt{pull}, or \texttt{push}, depending on the operation the
1154 client performed.
1155 \item[\texttt{url}] A URL. The location of the remote repository, if
1156 known. See section~\ref{sec:hook:url} for more information.
1157 \end{itemize}
1159 See also: \hook{preoutgoing} (section~\ref{sec:hook:preoutgoing})
1161 \subsection{\hook{prechangegroup}---before starting to add remote changesets}
1162 \label{sec:hook:prechangegroup}
1164 This controlling hook is run before Mercurial begins to add a group of
1165 changesets from another repository.
1167 This hook does not have any information about the changesets to be
1168 added, because it is run before transmission of those changesets is
1169 allowed to begin. If this hook fails, the changesets will not be
1170 transmitted.
1172 One use for this hook is to prevent external changes from being added
1173 to a repository. For example, you could use this to ``freeze'' a
1174 server-hosted branch temporarily or permanently so that users cannot
1175 push to it, while still allowing a local administrator to modify the
1176 repository.
1178 Parameters to this hook:
1179 \begin{itemize}
1180 \item[\texttt{source}] A string. The source of these changes. See
1181 section~\ref{sec:hook:sources} for details.
1182 \item[\texttt{url}] A URL. The location of the remote repository, if
1183 known. See section~\ref{sec:hook:url} for more information.
1184 \end{itemize}
1186 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
1187 \hook{incoming} (section~\ref{sec:hook:incoming}), ,
1188 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1190 \subsection{\hook{precommit}---before starting to commit a changeset}
1191 \label{sec:hook:precommit}
1193 This hook is run before Mercurial begins to commit a new changeset.
1194 It is run before Mercurial has any of the metadata for the commit,
1195 such as the files to be committed, the commit message, or the commit
1196 date.
1198 One use for this hook is to disable the ability to commit new
1199 changesets, while still allowing incoming changesets. Another is to
1200 run a build or test, and only allow the commit to begin if the build
1201 or test succeeds.
1203 Parameters to this hook:
1204 \begin{itemize}
1205 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1206 parent of the working directory.
1207 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1208 parent of the working directory.
1209 \end{itemize}
1210 If the commit proceeds, the parents of the working directory will
1211 become the parents of the new changeset.
1213 See also: \hook{commit} (section~\ref{sec:hook:commit}),
1214 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
1216 \subsection{\hook{preoutgoing}---before starting to propagate changesets}
1217 \label{sec:hook:preoutgoing}
1219 This hook is invoked before Mercurial knows the identities of the
1220 changesets to be transmitted.
1222 One use for this hook is to prevent changes from being transmitted to
1223 another repository.
1225 Parameters to this hook:
1226 \begin{itemize}
1227 \item[\texttt{source}] A string. The source of the operation that is
1228 attempting to obtain changes from this repository (see
1229 section~\ref{sec:hook:sources}). See the documentation for the
1230 \texttt{source} parameter to the \hook{outgoing} hook, in
1231 section~\ref{sec:hook:outgoing}, for possible values of this
1232 parameter.
1233 \item[\texttt{url}] A URL. The location of the remote repository, if
1234 known. See section~\ref{sec:hook:url} for more information.
1235 \end{itemize}
1237 See also: \hook{outgoing} (section~\ref{sec:hook:outgoing})
1239 \subsection{\hook{pretag}---before tagging a changeset}
1240 \label{sec:hook:pretag}
1242 This controlling hook is run before a tag is created. If the hook
1243 succeeds, creation of the tag proceeds. If the hook fails, the tag is
1244 not created.
1246 Parameters to this hook:
1247 \begin{itemize}
1248 \item[\texttt{local}] A boolean. Whether the tag is local to this
1249 repository instance (i.e.~stored in \sfilename{.hg/tags}) or managed
1250 by Mercurial (stored in \sfilename{.hgtags}).
1251 \item[\texttt{node}] A changeset ID. The ID of the changeset to be tagged.
1252 \item[\texttt{tag}] A string. The name of the tag to be created.
1253 \end{itemize}
1255 If the tag to be created is revision-controlled, the \hook{precommit}
1256 and \hook{pretxncommit} hooks (sections~\ref{sec:hook:commit}
1257 and~\ref{sec:hook:pretxncommit}) will also be run.
1259 See also: \hook{tag} (section~\ref{sec:hook:tag})
1261 \subsection{\hook{pretxnchangegroup}---before completing addition of
1262 remote changesets}
1263 \label{sec:hook:pretxnchangegroup}
1265 This controlling hook is run before a transaction---that manages the
1266 addition of a group of new changesets from outside the
1267 repository---completes. If the hook succeeds, the transaction
1268 completes, and all of the changesets become permanent within this
1269 repository. If the hook fails, the transaction is rolled back, and
1270 the data for the changesets is erased.
1272 This hook can access the metadata associated with the almost-added
1273 changesets, but it should not do anything permanent with this data.
1274 It must also not modify the working directory.
1276 While this hook is running, if other Mercurial processes access this
1277 repository, they will be able to see the almost-added changesets as if
1278 they are permanent. This may lead to race conditions if you do not
1279 take steps to avoid them.
1281 This hook can be used to automatically vet a group of changesets. If
1282 the hook fails, all of the changesets are ``rejected'' when the
1283 transaction rolls back.
1285 Parameters to this hook:
1286 \begin{itemize}
1287 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1288 changeset in the group that was added. All changesets between this
1289 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
1290 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
1291 \item[\texttt{source}] A string. The source of these changes. See
1292 section~\ref{sec:hook:sources} for details.
1293 \item[\texttt{url}] A URL. The location of the remote repository, if
1294 known. See section~\ref{sec:hook:url} for more information.
1295 \end{itemize}
1297 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
1298 \hook{incoming} (section~\ref{sec:hook:incoming}),
1299 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup})
1301 \subsection{\hook{pretxncommit}---before completing commit of new changeset}
1302 \label{sec:hook:pretxncommit}
1304 This controlling hook is run before a transaction---that manages a new
1305 commit---completes. If the hook succeeds, the transaction completes
1306 and the changeset becomes permanent within this repository. If the
1307 hook fails, the transaction is rolled back, and the commit data is
1308 erased.
1310 This hook can access the metadata associated with the almost-new
1311 changeset, but it should not do anything permanent with this data. It
1312 must also not modify the working directory.
1314 While this hook is running, if other Mercurial processes access this
1315 repository, they will be able to see the almost-new changeset as if it
1316 is permanent. This may lead to race conditions if you do not take
1317 steps to avoid them.
1319 Parameters to this hook:
1320 \begin{itemize}
1321 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
1322 committed changeset.
1323 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1324 parent of the newly committed changeset.
1325 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1326 parent of the newly committed changeset.
1327 \end{itemize}
1329 See also: \hook{precommit} (section~\ref{sec:hook:precommit})
1331 \subsection{\hook{preupdate}---before updating or merging working directory}
1332 \label{sec:hook:preupdate}
1334 This controlling hook is run before an update or merge of the working
1335 directory begins. It is run only if Mercurial's normal pre-update
1336 checks determine that the update or merge can proceed. If the hook
1337 succeeds, the update or merge may proceed; if it fails, the update or
1338 merge does not start.
1340 Parameters to this hook:
1341 \begin{itemize}
1342 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
1343 working directory is to be updated to. If the working directory is
1344 being merged, it will not change this parent.
1345 \item[\texttt{parent2}] A changeset ID. Only set if the working
1346 directory is being merged. The ID of the revision that the working
1347 directory is being merged with.
1348 \end{itemize}
1350 See also: \hook{update} (section~\ref{sec:hook:update})
1352 \subsection{\hook{tag}---after tagging a changeset}
1353 \label{sec:hook:tag}
1355 This hook is run after a tag has been created.
1357 Parameters to this hook:
1358 \begin{itemize}
1359 \item[\texttt{local}] A boolean. Whether the new tag is local to this
1360 repository instance (i.e.~stored in \sfilename{.hg/tags}) or managed
1361 by Mercurial (stored in \sfilename{.hgtags}).
1362 \item[\texttt{node}] A changeset ID. The ID of the changeset that was
1363 tagged.
1364 \item[\texttt{tag}] A string. The name of the tag that was created.
1365 \end{itemize}
1367 If the created tag is revision-controlled, the \hook{commit} hook
1368 (section~\ref{sec:hook:commit}) is run before this hook.
1370 See also: \hook{pretag} (section~\ref{sec:hook:pretag})
1372 \subsection{\hook{update}---after updating or merging working directory}
1373 \label{sec:hook:update}
1375 This hook is run after an update or merge of the working directory
1376 completes. Since a merge can fail (if the external \command{hgmerge}
1377 command fails to resolve conflicts in a file), this hook communicates
1378 whether the update or merge completed cleanly.
1380 \begin{itemize}
1381 \item[\texttt{error}] A boolean. Indicates whether the update or
1382 merge completed successfully.
1383 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
1384 working directory was updated to. If the working directory was
1385 merged, it will not have changed this parent.
1386 \item[\texttt{parent2}] A changeset ID. Only set if the working
1387 directory was merged. The ID of the revision that the working
1388 directory was merged with.
1389 \end{itemize}
1391 See also: \hook{preupdate} (section~\ref{sec:hook:preupdate})
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