hgbook
view en/hook.tex @ 62:8806b2875f10
Finish off a big whack of content for the hook chapter.
| author | Bryan O'Sullivan <bos@serpentine.com> |
|---|---|
| date | Fri Aug 04 13:29:38 2006 -0700 (2006-08-04) |
| parents | e94202d88199 |
| children | a00b562b4598 |
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[\texttt{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[\texttt{pull}] Control incoming changesets that are arriving via
543 a pull from a local repository.
544 \item[\texttt{push}] Control incoming changesets that are arriving via
545 a push from a local repository.
546 \item[\texttt{bundle}] Control incoming changesets that are arriving
547 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[\texttt{version}] The version of Bugzilla installed on the
653 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[\texttt{host}] The hostname of the MySQL server that stores your
657 Bugzilla data. The database must be configured to allow connections
658 from whatever host you are running the \hook{bugzilla} hook on.
659 \item[\texttt{user}] The username with which to connect to the MySQL
660 server. The database must be configured to allow this user to
661 connect from whatever host you are running the \hook{bugzilla} hook
662 on. This user must be able to access and modify Bugzilla tables.
663 The default value of this item is \texttt{bugs}, which is the
664 standard name of the Bugzilla user in a MySQL database.
665 \item[\texttt{password}] The MySQL password for the user you
666 configured above. This is stored as plain text, so you should make
667 sure that unauthorised users cannot read the \hgrc\ file where you
668 store this information.
669 \item[\texttt{db}] The name of the Bugzilla database on the MySQL
670 server. The default value of this item is \texttt{bugs}, which is
671 the standard name of the MySQL database where Bugzilla stores its
672 data.
673 \item[\texttt{notify}] If you want Bugzilla to send out a notification
674 email to subscribers after this hook has added a comment to a bug,
675 you will need this hook to run a command whenever it updates the
676 database. The command to run depends on where you have installed
677 Bugzilla, but it will typically look something like this, if you
678 have Bugzilla installed in \dirname{/var/www/html/bugzilla}:
679 \begin{codesample4}
680 cd /var/www/html/bugzilla && ./processmail %s nobody@nowhere.com
681 \end{codesample4}
682 The Bugzilla \texttt{processmail} program expects to be given a
683 bug~ID (the hook replaces ``\texttt{\%s}'' with the bug~ID) and an
684 email address. It also expects to be able to write to some files in
685 the directory that it runs in. If Bugzilla and this hook are not
686 installed on the same machine, you will need to find a way to run
687 \texttt{processmail} on the server where Bugzilla is installed.
688 \end{itemize}
690 \subsubsection{Mapping committer names to Bugzilla user names}
692 By default, the \hgext{bugzilla} hook tries to use the email address
693 of a changeset's committer as the Bugzilla user name with which to
694 update a bug. If this does not suit your needs, you can map committer
695 email addresses to Bugzilla user names using a \rcsection{usermap}
696 section.
698 Each item in the \rcsection{usermap} section contains an email address
699 on the left, and a Bugzilla user name on the right.
700 \begin{codesample2}
701 [usermap]
702 jane.user@example.com = jane
703 \end{codesample2}
704 You can either keep the \rcsection{usermap} data in a normal \hgrc, or
705 tell the \hgext{bugzilla} hook to read the information from an
706 external \filename{usermap} file. In the latter case, you can store
707 \filename{usermap} data by itself in (for example) a user-modifiable
708 repository. This makes it possible to let your users maintain their
709 own \texttt{usermap} entries. The main \hgrc\ file might look like
710 this:
711 \begin{codesample2}
712 # regular hgrc file refers to external usermap file
713 [bugzilla]
714 usermap = /home/hg/repos/userdata/bugzilla-usermap.conf
715 \end{codesample2}
716 While the \filename{usermap} file that it refers to might look like
717 this:
718 \begin{codesample2}
719 # bugzilla-usermap.conf - inside a hg repository
720 [usermap]
721 stephanie@example.com = steph
722 \end{codesample2}
724 \subsubsection{Configuring the text that gets added to a bug}
726 You can configure the text that this hook adds as a comment; you
727 specify it in the form of a Mercurial template. Several \hgrc\
728 entries (still in the \rcsection{bugzilla} section) control this
729 behaviour.
730 \begin{itemize}
731 \item[\texttt{hgweb}] The base string to use when constructing a URL
732 that will let users browse from a Bugzilla comment to view a
733 changeset. Example:
734 \begin{codesample4}
735 hgweb = http://hg.domain.com/
736 \end{codesample4}
737 \item[\texttt{strip}] The number of leading path elements to strip
738 from a repository's path name to construct a partial path for a URL.
739 For example, if the repositories on your server live under
740 \dirname{/home/hg/repos}, and you have a repository whose path is
741 \dirname{/home/hg/repos/app/tests}, then setting \texttt{strip} to
742 \texttt{4} will give a partial path of \dirname{app/tests}. The
743 hook will make this partial path available when expanding a
744 template, as \texttt{webroot}.
745 \item[\texttt{template}] The text of the template to use. In addition
746 to the usual changeset-related variables, this template can use
747 \texttt{hgweb} (the value of the \texttt{hgweb} configuration item
748 above) and \texttt{webroot} (the path constructed using
749 \texttt{strip} above).
750 \end{itemize}
752 Here is an example set of \hgext{bugzilla} hook config information.
753 \begin{codesample2}
754 [bugzilla]
755 host = bugzilla.example.com
756 password = mypassword
757 version = 2.16
758 # server-side repos live in /home/hg/repos, so strip 4 leading
759 # separators
760 strip = 4
761 hgweb = http://hg.example.com/
762 usermap = /home/hg/repos/notify/bugzilla.conf
763 template = Changeset \{node|short\}, made by \{author\} in the \{webroot\}
764 repo, refers to this bug.\\nFor complete details, see
765 \{hgweb\}\{webroot\}?cmd=changeset;node=\{node|short\}\\nChangeset
766 description:\\n\\t\{desc|tabindent\}
767 \end{codesample2}
769 \subsubsection{Testing and troubleshooting}
771 The most common problems with configuring the \hgext{bugzilla} hook
772 relate to running Bugzilla's \filename{processmail} script and mapping
773 committer names to user names.
775 Recall from section~\ref{sec:hook:bugzilla:config} above that the user
776 that runs the Mercurial process on the server is also the one that
777 will run the \filename{processmail} script. The
778 \filename{processmail} script sometimes causes Bugzilla to write to
779 files in its configuration directory, and Bugzilla's configuration
780 files are usually owned by the user that your web server runs under.
782 You can cause \filename{processmail} to be run with the suitable
783 user's identity using the \command{sudo} command. Here is an example
784 entry for a \filename{sudoers} file.
785 \begin{codesample2}
786 hg_user = (httpd_user) NOPASSWD: /var/www/html/bugzilla/processmail-wrapper %s
787 \end{codesample2}
788 This allows the \texttt{hg\_user} user to run a
789 \filename{processmail-wrapper} program under the identity of
790 \texttt{httpd\_user}.
792 This indirection through a wrapper script is necessary, because
793 \filename{processmail} expects to be run with its current directory
794 set to wherever you installed Bugzilla; you can't specify that kind of
795 constraint in a \filename{sudoers} file. The contents of the wrapper
796 script are simple:
797 \begin{codesample2}
798 #!/bin/sh
799 cd `dirname $0` && ./processmail "$1" nobody@example.com
800 \end{codesample2}
801 It doesn't seem to matter what email address you pass to
802 \filename{processmail}.
804 If your \rcsection{usermap} is not set up correctly, users will see an
805 error message from the \hgext{bugzilla} hook when they push changes
806 to the server. The error message will look like this:
807 \begin{codesample2}
808 cannot find bugzilla user id for john.q.public@example.com
809 \end{codesample2}
810 What this means is that the committer's address,
811 \texttt{john.q.public@example.com}, is not a valid Bugzilla user name,
812 nor does it have an entry in your \rcsection{usermap} that maps it to
813 a valid Bugzilla user name.
815 \subsection{\hgext{notify}---send email notifications}
817 Although Mercurial's built-in web server provides RSS feeds of changes
818 in every repository, many people prefer to receive change
819 notifications via email. The \hgext{notify} hook lets you send out
820 notifications to a set of email addresses whenever changesets arrive
821 that those subscribers are interested in.
823 As with the \hgext{bugzilla} hook, the \hgext{notify} hook is
824 template-driven, so you can customise the contents of the notification
825 messages that it sends.
827 By default, the \hgext{notify} hook includes a diff of every changeset
828 that it sends outd; you can limit the size of the diff, or turn this
829 feature off entirely. It is useful for letting subscribers review
830 changes immediately, rather than clicking to follow a URL.
832 \subsubsection{Configuring the \hgext{notify} hook}
834 You can set up the \hgext{notify} hook to send one email message per
835 incoming changeset, or one per incoming group of changesets (all those
836 that arrived in a single pull or push).
837 \begin{codesample2}
838 [hooks]
839 # send one email per group of changes
840 changegroup.notify = python:hgext.notify.hook
841 # send one email per change
842 incoming.notify = python:hgext.notify.hook
843 \end{codesample2}
845 Configuration information for this hook lives in the
846 \rcsection{notify} section of a \hgrc\ file.
847 \begin{itemize}
848 \item[\rcitem{notify}{test}] By default, this hook does not send out
849 email at all; instead, it prints the message that it \emph{would}
850 send. Set this item to \texttt{false} to allow email to be sent.
851 The reason that sending of email is turned off by default is that it
852 takes several tries to configure this extension exactly as you would
853 like, and it would be bad form to spam subscribers with a number of
854 ``broken'' notifications while you debug your configuration.
855 \item[\rcitem{notify}{config}] The path to a configuration file that
856 contains subbscription information. This is kept separate from the
857 main \hgrc\ so that you can maintain it in a repository of its own.
858 People can then clone that repository, update their subscriptions,
859 and push the changes back to your server.
860 \item[\rcitem{notify}{strip}] The number of leading path separator
861 characters to strip from a repository's path, when deciding whether
862 a repository has subscribers. For example, if the repositories on
863 your server live in \dirname{/home/hg/repos}, and \hgext{notify} is
864 considering a repository named \dirname{/home/hg/repos/shared/test},
865 setting \rcitem{notify}{strip} to \texttt{4} will cause
866 \hgext{notify} to trim the path it considers down to
867 \dirname{shared/test}, and it will match subscribers against that.
868 \item[\rcitem{notify}{template}] The template text to use when sending
869 messages. This specifies both the contents of the message header
870 and its body.
871 \item[\rcitem{notify}{maxdiff}] The maximum number of lines of diff
872 data to append to the end of a message. If a diff is longer than
873 this, it is truncated. By default, this is set to 300. Set this to
874 \texttt{0} to omit diffs from notification emails.
875 \item[\rcitem{notify}{sources}] A list of sources of changesets to
876 consider. This lets you limit \hgext{notify} to only sending out
877 email about changes that remote users pushed into this repository
878 via a server, for example. See section~\ref{sec:hook:sources} for
879 the sources you can specify here.
880 \end{itemize}
882 If you set the \rcitem{web}{baseurl} item in the \rcsection{web}
883 section, you can use it in a template; it will be available as
884 \texttt{webroot}.
886 Here is an example set of \hgext{notify} configuration information.
887 \begin{codesample2}
888 [notify]
889 # really send email
890 test = false
891 # subscriber data lives in the notify repo
892 config = /home/hg/repos/notify/notify.conf
893 # repos live in /home/hg/repos on server, so strip 4 "/" chars
894 strip = 4
895 template = X-Hg-Repo: \{webroot\}\\n\\\\
896 Subject: \{webroot\}: \{desc|firstline|strip\}\\n\\\\
897 From: \{author\}\\n\\\\
898 \\n\\\\
899 changeset \{node|short\} in \{root\}\\n\\\\
900 details: \{baseurl\}\{webroot\}?cmd=changeset;node=\{node|short\}\\n\\\\
901 description:\\n\\\\
902 \\t\{desc|tabindent|strip\}
904 [web]
905 baseurl = http://hg.example.com/
906 \end{codesample2}
908 This will produce a message that looks like the following:
909 \begin{codesample2}
910 X-Hg-Repo: tests/slave
911 Subject: tests/slave: Handle error case when slave has no buffers
912 Date: Wed, 2 Aug 2006 15:25:46 -0700 (PDT)
914 changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave
915 details: http://hg.example.com/tests/slave?cmd=changeset;node=3cba9bfe74b5
916 description:
917 Handle error case when slave has no buffers
918 diffs (54 lines):
920 diff -r 9d95df7cf2ad -r 3cba9bfe74b5 include/tests.h
921 --- a/include/tests.h Wed Aug 02 15:19:52 2006 -0700
922 +++ b/include/tests.h Wed Aug 02 15:25:26 2006 -0700
923 @@ -212,6 +212,15 @@ static __inline__ void test_headers(void *h)
924 [...snip...]
925 \end{codesample2}
927 \subsubsection{Testing and troubleshooting}
929 Do not forget that by default, the \hgext{notify} extension \emph{will
930 not send any mail} until you explicitly configure it to do so, by
931 setting \rcitem{notify}{test} to \texttt{false}. Until you do that,
932 it simply prints the message it \emph{would} send.
934 \section{Hook reference}
935 \label{sec:hook:ref}
937 \subsection{In-process hook execution}
939 An in-process hook is called with arguments of the following form:
940 \begin{codesample2}
941 def myhook(ui, repo, **kwargs):
942 pass
943 \end{codesample2}
944 The \texttt{ui} parameter is a \pymodclass{mercurial.ui}{ui} object.
945 The \texttt{repo} parameter is a
946 \pymodclass{mercurial.localrepo}{localrepository} object. The
947 names and values of the \texttt{**kwargs} parameters depend on the
948 hook being invoked, with the following common features:
949 \begin{itemize}
950 \item If a parameter is named \texttt{node} or
951 \texttt{parent\emph{N}}, it will contain a hexadecimal changeset ID.
952 The empty string is used to represent ``null changeset ID'' instead
953 of a string of zeroes.
954 \item If a parameter is named \texttt{url}, it will contain the URL of
955 a remote repository, if that can be determined.
956 \item Boolean-valued parameters are represented as Python
957 \texttt{bool} objects.
958 \end{itemize}
960 An in-process hook is called without a change to the process's working
961 directory (unlike external hooks, which are run in the root of the
962 repository). It must not change the process's working directory, or
963 it will cause any calls it makes into the Mercurial API to fail.
965 If a hook returns a boolean ``false'' value, it is considered to have
966 succeeded. If it returns a boolean ``true'' value or raises an
967 exception, it is considered to have failed. A useful way to think of
968 the calling convention is ``tell me if you fail''.
970 Note that changeset IDs are passed into Python hooks as hexadecimal
971 strings, not the binary hashes that Mercurial's APIs normally use. To
972 convert a hash from hex to binary, use the
973 \pymodfunc{mercurial.node}{bin} function.
975 \subsection{External hook execution}
977 An external hook is passed to the shell of the user running Mercurial.
978 Features of that shell, such as variable substitution and command
979 redirection, are available. The hook is run in the root directory of
980 the repository (unlike in-process hooks, which are run in the same
981 directory that Mercurial was run in).
983 Hook parameters are passed to the hook as environment variables. Each
984 environment variable's name is converted in upper case and prefixed
985 with the string ``\texttt{HG\_}''. For example, if the name of a
986 parameter is ``\texttt{node}'', the name of the environment variable
987 representing that parameter will be ``\texttt{HG\_NODE}''.
989 A boolean parameter is represented as the string ``\texttt{1}'' for
990 ``true'', ``\texttt{0}'' for ``false''. If an environment variable is
991 named \envar{HG\_NODE}, \envar{HG\_PARENT1} or \envar{HG\_PARENT2}, it
992 contains a changeset ID represented as a hexadecimal string. The
993 empty string is used to represent ``null changeset ID'' instead of a
994 string of zeroes. If an environment variable is named
995 \envar{HG\_URL}, it will contain the URL of a remote repository, if
996 that can be determined.
998 If a hook exits with a status of zero, it is considered to have
999 succeeded. If it exits with a non-zero status, it is considered to
1000 have failed.
1002 \subsection{Finding out where changesets come from}
1004 A hook that involves the transfer of changesets between a local
1005 repository and another may be able to find out information about the
1006 ``far side''. Mercurial knows \emph{how} changes are being
1007 transferred, and in many cases \emph{where} they are being transferred
1008 to or from.
1010 \subsubsection{Sources of changesets}
1011 \label{sec:hook:sources}
1013 Mercurial will tell a hook what means are, or were, used to transfer
1014 changesets between repositories. This is provided by Mercurial in a
1015 Python parameter named \texttt{source}, or an environment variable named
1016 \envar{HG\_SOURCE}.
1018 \begin{itemize}
1019 \item[\texttt{serve}] Changesets are transferred to or from a remote
1020 repository over http or ssh.
1021 \item[\texttt{pull}] Changesets are being transferred via a pull from
1022 one repository into another.
1023 \item[\texttt{push}] Changesets are being transferred via a push from
1024 one repository into another.
1025 \item[\texttt{bundle}] Changesets are being transferred to or from a
1026 bundle.
1027 \end{itemize}
1029 \subsubsection{Where changes are going---remote repository URLs}
1030 \label{sec:hook:url}
1032 When possible, Mercurial will tell a hook the location of the ``far
1033 side'' of an activity that transfers changeset data between
1034 repositories. This is provided by Mercurial in a Python parameter
1035 named \texttt{url}, or an environment variable named \envar{HG\_URL}.
1037 This information is not always known. If a hook is invoked in a
1038 repository that is being served via http or ssh, Mercurial cannot tell
1039 where the remote repository is, but it may know where the client is
1040 connecting from. In such cases, the URL will take one of the
1041 following forms:
1042 \begin{itemize}
1043 \item \texttt{remote:ssh:\emph{ip-address}}---remote ssh client, at
1044 the given IP address.
1045 \item \texttt{remote:http:\emph{ip-address}}---remote http client, at
1046 the given IP address. If the client is using SSL, this will be of
1047 the form \texttt{remote:https:\emph{ip-address}}.
1048 \item Empty---no information could be discovered about the remote
1049 client.
1050 \end{itemize}
1052 \subsection{The \hook{changegroup} hook}
1053 \label{sec:hook:changegroup}
1055 This hook is run after a group of pre-existing changesets has been
1056 added to the repository, for example via a \hgcmd{pull} or
1057 \hgcmd{unbundle}. This hook is run once per operation that added one
1058 or more changesets. This is in contrast to the \hook{incoming} hook,
1059 which is run once per changeset, regardless of whether the changesets
1060 arrive in a group.
1062 Some possible uses for this hook include kicking off an automated
1063 build or test of the added changesets, updating a bug database, or
1064 notifying subscribers that a repository contains new changes.
1066 Parameters to this hook:
1067 \begin{itemize}
1068 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1069 changeset in the group that was added. All changesets between this
1070 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
1071 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
1072 \item[\texttt{source}] A string. The source of these changes. See
1073 section~\ref{sec:hook:sources} for details.
1074 \item[\texttt{url}] A URL. The location of the remote repository, if
1075 known. See section~\ref{sec:hook:url} for more information.
1076 \end{itemize}
1078 See also: \hook{incoming} (section~\ref{sec:hook:incoming}),
1079 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}),
1080 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1082 \subsection{The \hook{commit} hook}
1083 \label{sec:hook:commit}
1085 This hook is run after a new changeset has been created.
1087 Parameters to this hook:
1088 \begin{itemize}
1089 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
1090 committed changeset.
1091 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1092 parent of the newly committed changeset.
1093 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1094 parent of the newly committed changeset.
1095 \end{itemize}
1097 See also: \hook{precommit} (section~\ref{sec:hook:precommit}),
1098 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
1100 \subsection{The \hook{incoming} hook}
1101 \label{sec:hook:incoming}
1103 This hook is run after a pre-existing changeset has been added to the
1104 repository, for example via a \hgcmd{push}. If a group of changesets
1105 was added in a single operation, this hook is called once for each
1106 added changeset.
1108 You can use this hook for the same purposes as the \hook{changegroup}
1109 hook (section~\ref{sec:hook:changegroup}); it's simply more convenient
1110 sometimes to run a hook once per group of changesets, while other
1111 times it's handier once per changeset.
1113 Parameters to this hook:
1114 \begin{itemize}
1115 \item[\texttt{node}] A changeset ID. The ID of the newly added
1116 changeset.
1117 \item[\texttt{source}] A string. The source of these changes. See
1118 section~\ref{sec:hook:sources} for details.
1119 \item[\texttt{url}] A URL. The location of the remote repository, if
1120 known. See section~\ref{sec:hook:url} for more information.
1121 \end{itemize}
1123 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}) \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}), \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1125 \subsection{The \hook{outgoing} hook}
1126 \label{sec:hook:outgoing}
1128 This hook is run after a group of changesets has been propagated out
1129 of this repository, for example by a \hgcmd{push} or \hgcmd{bundle}
1130 command.
1132 One possible use for this hook is to notify administrators that
1133 changes have been pulled.
1135 Parameters to this hook:
1136 \begin{itemize}
1137 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1138 changeset of the group that was sent.
1139 \item[\texttt{source}] A string. The source of the of the operation
1140 (see section~\ref{sec:hook:sources}). If a remote client pulled
1141 changes from this repository, \texttt{source} will be
1142 \texttt{serve}. If the client that obtained changes from this
1143 repository was local, \texttt{source} will be \texttt{bundle},
1144 \texttt{pull}, or \texttt{push}, depending on the operation the
1145 client performed.
1146 \item[\texttt{url}] A URL. The location of the remote repository, if
1147 known. See section~\ref{sec:hook:url} for more information.
1148 \end{itemize}
1150 See also: \hook{preoutgoing} (section~\ref{sec:hook:preoutgoing})
1152 \subsection{The \hook{prechangegroup} hook}
1153 \label{sec:hook:prechangegroup}
1155 This controlling hook is run before Mercurial begins to add a group of
1156 changesets from another repository.
1158 This hook does not have any information about the changesets to be
1159 added, because it is run before transmission of those changesets is
1160 allowed to begin. If this hook fails, the changesets will not be
1161 transmitted.
1163 One use for this hook is to prevent external changes from being added
1164 to a repository. For example, you could use this to ``freeze'' a
1165 server-hosted branch temporarily or permanently so that users cannot
1166 push to it, while still allowing a local administrator to modify the
1167 repository.
1169 Parameters to this hook:
1170 \begin{itemize}
1171 \item[\texttt{source}] A string. The source of these changes. See
1172 section~\ref{sec:hook:sources} for details.
1173 \item[\texttt{url}] A URL. The location of the remote repository, if
1174 known. See section~\ref{sec:hook:url} for more information.
1175 \end{itemize}
1177 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
1178 \hook{incoming} (section~\ref{sec:hook:incoming}), ,
1179 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1181 \subsection{The \hook{precommit} hook}
1182 \label{sec:hook:precommit}
1184 This hook is run before Mercurial begins to commit a new changeset.
1185 It is run before Mercurial has any of the metadata for the commit,
1186 such as the files to be committed, the commit message, or the commit
1187 date.
1189 One use for this hook is to disable the ability to commit new
1190 changesets, while still allowing incoming changesets. Another is to
1191 run a build or test, and only allow the commit to begin if the build
1192 or test succeeds.
1194 Parameters to this hook:
1195 \begin{itemize}
1196 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1197 parent of the working directory.
1198 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1199 parent of the working directory.
1200 \end{itemize}
1201 If the commit proceeds, the parents of the working directory will
1202 become the parents of the new changeset.
1204 See also: \hook{commit} (section~\ref{sec:hook:commit}),
1205 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
1207 \subsection{The \hook{preoutgoing} hook}
1208 \label{sec:hook:preoutgoing}
1210 This hook is invoked before Mercurial knows the identities of the
1211 changesets to be transmitted.
1213 One use for this hook is to prevent changes from being transmitted to
1214 another repository.
1216 Parameters to this hook:
1217 \begin{itemize}
1218 \item[\texttt{source}] A string. The source of the operation that is
1219 attempting to obtain changes from this repository (see
1220 section~\ref{sec:hook:sources}). See the documentation for the
1221 \texttt{source} parameter to the \hook{outgoing} hook, in
1222 section~\ref{sec:hook:outgoing}, for possible values of this
1223 parameter.
1224 \item[\texttt{url}] A URL. The location of the remote repository, if
1225 known. See section~\ref{sec:hook:url} for more information.
1226 \end{itemize}
1228 See also: \hook{outgoing} (section~\ref{sec:hook:outgoing})
1230 \subsection{The \hook{pretag} hook}
1231 \label{sec:hook:pretag}
1233 This controlling hook is run before a tag is created. If the hook
1234 succeeds, creation of the tag proceeds. If the hook fails, the tag is
1235 not created.
1237 Parameters to this hook:
1238 \begin{itemize}
1239 \item[\texttt{local}] A boolean. Whether the tag is local to this
1240 repository instance (i.e.~stored in \sfilename{.hg/tags}) or managed
1241 by Mercurial (stored in \sfilename{.hgtags}).
1242 \item[\texttt{node}] A changeset ID. The ID of the changeset to be tagged.
1243 \item[\texttt{tag}] A string. The name of the tag to be created.
1244 \end{itemize}
1246 If the tag to be created is revision-controlled, the \hook{precommit}
1247 and \hook{pretxncommit} hooks (sections~\ref{sec:hook:commit}
1248 and~\ref{sec:hook:pretxncommit}) will also be run.
1250 See also: \hook{tag} (section~\ref{sec:hook:tag})
1252 \subsection{The \hook{pretxnchangegroup} hook}
1253 \label{sec:hook:pretxnchangegroup}
1255 This controlling hook is run before a transaction---that manages the
1256 addition of a group of new changesets from outside the
1257 repository---completes. If the hook succeeds, the transaction
1258 completes, and all of the changesets become permanent within this
1259 repository. If the hook fails, the transaction is rolled back, and
1260 the data for the changesets is erased.
1262 This hook can access the metadata associated with the almost-added
1263 changesets, but it should not do anything permanent with this data.
1264 It must also not modify the working directory.
1266 While this hook is running, if other Mercurial processes access this
1267 repository, they will be able to see the almost-added changesets as if
1268 they are permanent. This may lead to race conditions if you do not
1269 take steps to avoid them.
1271 This hook can be used to automatically vet a group of changesets. If
1272 the hook fails, all of the changesets are ``rejected'' when the
1273 transaction rolls back.
1275 Parameters to this hook:
1276 \begin{itemize}
1277 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1278 changeset in the group that was added. All changesets between this
1279 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
1280 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
1281 \item[\texttt{source}] A string. The source of these changes. See
1282 section~\ref{sec:hook:sources} for details.
1283 \item[\texttt{url}] A URL. The location of the remote repository, if
1284 known. See section~\ref{sec:hook:url} for more information.
1285 \end{itemize}
1287 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
1288 \hook{incoming} (section~\ref{sec:hook:incoming}),
1289 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup})
1291 \subsection{The \hook{pretxncommit} hook}
1292 \label{sec:hook:pretxncommit}
1294 This controlling hook is run before a transaction---that manages a new
1295 commit---completes. If the hook succeeds, the transaction completes
1296 and the changeset becomes permanent within this repository. If the
1297 hook fails, the transaction is rolled back, and the commit data is
1298 erased.
1300 This hook can access the metadata associated with the almost-new
1301 changeset, but it should not do anything permanent with this data. It
1302 must also not modify the working directory.
1304 While this hook is running, if other Mercurial processes access this
1305 repository, they will be able to see the almost-new changeset as if it
1306 is permanent. This may lead to race conditions if you do not take
1307 steps to avoid them.
1309 Parameters to this hook:
1310 \begin{itemize}
1311 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
1312 committed changeset.
1313 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1314 parent of the newly committed changeset.
1315 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1316 parent of the newly committed changeset.
1317 \end{itemize}
1319 See also: \hook{precommit} (section~\ref{sec:hook:precommit})
1321 \subsection{The \hook{preupdate} hook}
1322 \label{sec:hook:preupdate}
1324 This controlling hook is run before an update or merge of the working
1325 directory begins. It is run only if Mercurial's normal pre-update
1326 checks determine that the update or merge can proceed. If the hook
1327 succeeds, the update or merge may proceed; if it fails, the update or
1328 merge does not start.
1330 Parameters to this hook:
1331 \begin{itemize}
1332 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
1333 working directory is to be updated to. If the working directory is
1334 being merged, it will not change this parent.
1335 \item[\texttt{parent2}] A changeset ID. Only set if the working
1336 directory is being merged. The ID of the revision that the working
1337 directory is being merged with.
1338 \end{itemize}
1340 See also: \hook{update} (section~\ref{sec:hook:update})
1342 \subsection{The \hook{tag} hook}
1343 \label{sec:hook:tag}
1345 This hook is run after a tag has been created.
1347 Parameters to this hook:
1348 \begin{itemize}
1349 \item[\texttt{local}] A boolean. Whether the new tag is local to this
1350 repository instance (i.e.~stored in \sfilename{.hg/tags}) or managed
1351 by Mercurial (stored in \sfilename{.hgtags}).
1352 \item[\texttt{node}] A changeset ID. The ID of the changeset that was
1353 tagged.
1354 \item[\texttt{tag}] A string. The name of the tag that was created.
1355 \end{itemize}
1357 If the created tag is revision-controlled, the \hook{commit} hook
1358 (section~\ref{sec:hook:commit}) is run before this hook.
1360 See also: \hook{pretag} (section~\ref{sec:hook:pretag})
1362 \subsection{The \hook{update} hook}
1363 \label{sec:hook:update}
1365 This hook is run after an update or merge of the working directory
1366 completes. Since a merge can fail (if the external \command{hgmerge}
1367 command fails to resolve conflicts in a file), this hook communicates
1368 whether the update or merge completed cleanly.
1370 \begin{itemize}
1371 \item[\texttt{error}] A boolean. Indicates whether the update or
1372 merge completed successfully.
1373 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
1374 working directory was updated to. If the working directory was
1375 merged, it will not have changed this parent.
1376 \item[\texttt{parent2}] A changeset ID. Only set if the working
1377 directory was merged. The ID of the revision that the working
1378 directory was merged with.
1379 \end{itemize}
1381 See also: \hook{preupdate} (section~\ref{sec:hook:preupdate})
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