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| author | jerojasro@localhost |
|---|---|
| date | Mon Dec 01 21:53:26 2008 -0500 (2008-12-01) |
| parents | 7e52f0cc4516 |
| children | 05bfbe50e7e4 |
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1 \chapter{Manejo de eventos en repositorios con ganchos}
2 \label{chap:hook}
4 Mercurial ofrece un poderoso mecanismo para permitirle a usted
5 automatizar la ejecución de acciones en respuesta a eventos que
6 ocurran en un repositorio. En algunos casos, usted puede controlar
7 incluso la respuesta de Mercurial a dichos eventos.
9 Mercurial usa el término \emph{gancho} para identificar estas
10 acciones. Los ganchos son conocidos como ``disparadores'' en algunos
11 sistemas de control de revisiones, pero los dos nombres se refieren al
12 mismo concepto.
14 \section{Vistazo general de ganchos en Mercurial}
16 A continuación se encuentra una breve lista de los ganchos que
17 Mercurial soporta. Volveremos a cada uno de estos ganchos con más
18 detalle después, en la sección~\ref{sec:hook:ref}.
20 \begin{itemize}
21 \item[\small\hook{changegroup}] Es ejecutado luego de que un grupo de
22 conjuntos de cambios ha sido traído al repositorio desde algún
23 otro sitio.
24 \item[\small\hook{commit}] Es ejecutado después de la creación de
25 un conjunto de cambios en el repositorio local.
26 \item[\small\hook{incoming}] Es ejecutado una vez por cada conjunto de
27 cambios traído al repositorio desde otra ubicación. Note la
28 diferencia respecto al gancho \hook{changegroup}, que es ejecutado
29 una vez por cada \emph{grupo} de conjuntos de cambios que se
30 traiga.
31 \item[\small\hook{outgoing}] Es ejecutado luego de que un grupo de
32 conjuntos de cambios ha sido transmitido desde el repositorio.
33 \item[\small\hook{prechangegroup}] Es ejecutado antes de iniciar la
34 recepción de un grupo de conjuntos de cambios en el repositorio.
35 \item[\small\hook{precommit}] De control. Es ejecutado antes de
36 iniciar una consignación.
37 \item[\small\hook{preoutgoing}] De control. Es ejecutado antes de
38 iniciar la transmisión de un grupo de conjuntos de cambios desde
39 el repositorio.
40 \item[\small\hook{pretag}] De control. Es ejecutado antes de crear una
41 etiqueta.
42 \item[\small\hook{pretxnchangegroup}] De control. Es ejecutado después
43 de haber recibido un grupo de conjuntos de cambios en el
44 repositorio local, pero antes de que la transacción se complete y
45 los cambios sean permanentes dentro del repositorio.
46 \item[\small\hook{pretxncommit}] De control. Es ejecutado luego de la
47 creación de un conjunto de cambios en el repositorio local, pero
48 antes de que la transacción que hace permanente el cambio sea
49 completada.
50 \item[\small\hook{preupdate}] De control. Es ejecutado antes de
51 iniciar una actualización o fusión en el directorio de trabajo.
52 \item[\small\hook{tag}] Es ejecutado después de la creación de una
53 etiqueta.
54 \item[\small\hook{update}] Es ejecutado después de que termina una
55 actualización o una fusión.
56 \end{itemize}
57 Cada uno de los ganchos cuya descripción empieza con la frase
58 ``de control'' tiene la facultad de determinar si una actividad puede
59 continuar. Si el gancho se ejecuta con éxito, la actividad puede
60 continuar; si falla, o bien la actividad no es permitida, o se
61 deshacen los cambios que se puedan haber llevado a cabo, dependiendo
62 del gancho involucrado.
64 \section{Ganchos y seguridad}
66 \subsection{Los ganchos se ejecutan con sus privilegios de usuario}
68 Cuando usted ejecuta un comando de Mercurial en un repositorio, y el
69 comando causa la ejecución de un gancho, dicho gancho se ejecuta en
70 \emph{su} sistema, en \emph{su} cuenta de usuario, con \emph{sus}
71 privilegios. Ya que los ganchos son elementos arbitrarios de código
72 ejecutable, usted debería tratarlos con un nivel adecuado de
73 desconfianza. No instale un gancho a menos en que confíe en quien lo
74 creó y en lo que el gancho hace.
76 En algunos casos, usted puede estar expuesto a ganchos que usted no
77 %TODO acá introduzco algo de texto por mi cuenta, por claridad
78 instaló. Si usted usa Mercurial en un sistema extraño, tenga en cuenta
79 que Mercurial ejecutará los ganchos definidos en el fichero \hgrc.
81 Si está trabajando con un repositorio propiedad de otro usuario,
82 Mercurial podrá ejecutar los ganchos definidos en el repositorio de
83 dicho usuario, pero los ejecutará como ``usted''. Por ejemplo, si
84 usted jala (\hgcmd{pull}) desde ese repositorio, y el
85 \sfilename{.hg/hgrc} define un gancho saliente (\hook{outgoing}),
86 dicho gancho se ejecuta bajo su cuenta de usuario, aun cuando usted no
87 es el propietario del repositorio.
89 \begin{note}
90 Esto sólo aplica si usted está jalando desde un repositorio en un
91 sistema de ficheros local o de red. Si está jalando a través de http
92 o ssh, cualquier gancho saliente (\hook{outgoing}) se ejecutará bajo
93 la cuenta que está ejecutando el proceso servidor, en el servidor.
94 \end{note}
96 XXX Para ver qué ganchos han sido definidos en un repositorio, use el
97 comando \hgcmdargs{config}{hooks}. Si usted está trabajando en un
98 repositorio, pero comunicándose con otro que no le pertenece
99 (por ejemplo, usando \hgcmd{pull} o \hgcmd{incoming}), recuerde que
100 los ganchos que debe considerar son los del otro repositorio, no los
101 del suyo.
103 \subsection{Los ganchos no se propagan}
105 En Mercurial, no se hace control de revisiones de los ganchos, y no se
106 propagan cuando usted clona, o jala de, un repositorio. El motivo para
107 esto es simple: un gancho es código ejecutable arbitrario. Se ejecuta
108 bajo su identidad, con su nivel de privilegios, en su máquina.
110 Sería extremadamente descuidado de parte de cualquier sistema
111 distribuido de control de revisiones el implementar control de
112 revisiones para ganchos, ya que esto ofrecería maneras fácilmente
113 %TODO subvertir
114 aprovechables de subvertir las cuentas de los usuarios del sistema de
115 control de revisiones.
117 Ya que Mercurial no propaga los ganchos, si usted está colaborando con
118 otras personas en un proyecto común, no debería asumir que ellos están
119 usando los mismos ganchos para Mercurial que usted usa, o que los de
120 ellos están configurado correctamente. Usted debería documentar los
121 ganchos que usted espera que la gente use.
123 In a corporate intranet, this is somewhat easier to control, as you
124 can for example provide a ``standard'' installation of Mercurial on an
125 NFS filesystem, and use a site-wide \hgrc\ file to define hooks that
126 all users will see. However, this too has its limits; see below.
128 \subsection{Hooks can be overridden}
130 Mercurial allows you to override a hook definition by redefining the
131 hook. You can disable it by setting its value to the empty string, or
132 change its behaviour as you wish.
134 If you deploy a system-~or site-wide \hgrc\ file that defines some
135 hooks, you should thus understand that your users can disable or
136 override those hooks.
138 \subsection{Ensuring that critical hooks are run}
140 Sometimes you may want to enforce a policy that you do not want others
141 to be able to work around. For example, you may have a requirement
142 that every changeset must pass a rigorous set of tests. Defining this
143 requirement via a hook in a site-wide \hgrc\ won't work for remote
144 users on laptops, and of course local users can subvert it at will by
145 overriding the hook.
147 Instead, you can set up your policies for use of Mercurial so that
148 people are expected to propagate changes through a well-known
149 ``canonical'' server that you have locked down and configured
150 appropriately.
152 One way to do this is via a combination of social engineering and
153 technology. Set up a restricted-access account; users can push
154 changes over the network to repositories managed by this account, but
155 they cannot log into the account and run normal shell commands. In
156 this scenario, a user can commit a changeset that contains any old
157 garbage they want.
159 When someone pushes a changeset to the server that everyone pulls
160 from, the server will test the changeset before it accepts it as
161 permanent, and reject it if it fails to pass the test suite. If
162 people only pull changes from this filtering server, it will serve to
163 ensure that all changes that people pull have been automatically
164 vetted.
166 \section{Care with \texttt{pretxn} hooks in a shared-access repository}
168 If you want to use hooks to do some automated work in a repository
169 that a number of people have shared access to, you need to be careful
170 in how you do this.
172 Mercurial only locks a repository when it is writing to the
173 repository, and only the parts of Mercurial that write to the
174 repository pay attention to locks. Write locks are necessary to
175 prevent multiple simultaneous writers from scribbling on each other's
176 work, corrupting the repository.
178 Because Mercurial is careful with the order in which it reads and
179 writes data, it does not need to acquire a lock when it wants to read
180 data from the repository. The parts of Mercurial that read from the
181 repository never pay attention to locks. This lockless reading scheme
182 greatly increases performance and concurrency.
184 With great performance comes a trade-off, though, one which has the
185 potential to cause you trouble unless you're aware of it. To describe
186 this requires a little detail about how Mercurial adds changesets to a
187 repository and reads those changes.
189 When Mercurial \emph{writes} metadata, it writes it straight into the
190 destination file. It writes file data first, then manifest data
191 (which contains pointers to the new file data), then changelog data
192 (which contains pointers to the new manifest data). Before the first
193 write to each file, it stores a record of where the end of the file
194 was in its transaction log. If the transaction must be rolled back,
195 Mercurial simply truncates each file back to the size it was before the
196 transaction began.
198 When Mercurial \emph{reads} metadata, it reads the changelog first,
199 then everything else. Since a reader will only access parts of the
200 manifest or file metadata that it can see in the changelog, it can
201 never see partially written data.
203 Some controlling hooks (\hook{pretxncommit} and
204 \hook{pretxnchangegroup}) run when a transaction is almost complete.
205 All of the metadata has been written, but Mercurial can still roll the
206 transaction back and cause the newly-written data to disappear.
208 If one of these hooks runs for long, it opens a window of time during
209 which a reader can see the metadata for changesets that are not yet
210 permanent, and should not be thought of as ``really there''. The
211 longer the hook runs, the longer that window is open.
213 \subsection{The problem illustrated}
215 In principle, a good use for the \hook{pretxnchangegroup} hook would
216 be to automatically build and test incoming changes before they are
217 accepted into a central repository. This could let you guarantee that
218 nobody can push changes to this repository that ``break the build''.
219 But if a client can pull changes while they're being tested, the
220 usefulness of the test is zero; an unsuspecting someone can pull
221 untested changes, potentially breaking their build.
223 The safest technological answer to this challenge is to set up such a
224 ``gatekeeper'' repository as \emph{unidirectional}. Let it take
225 changes pushed in from the outside, but do not allow anyone to pull
226 changes from it (use the \hook{preoutgoing} hook to lock it down).
227 Configure a \hook{changegroup} hook so that if a build or test
228 succeeds, the hook will push the new changes out to another repository
229 that people \emph{can} pull from.
231 In practice, putting a centralised bottleneck like this in place is
232 not often a good idea, and transaction visibility has nothing to do
233 with the problem. As the size of a project---and the time it takes to
234 build and test---grows, you rapidly run into a wall with this ``try
235 before you buy'' approach, where you have more changesets to test than
236 time in which to deal with them. The inevitable result is frustration
237 on the part of all involved.
239 An approach that scales better is to get people to build and test
240 before they push, then run automated builds and tests centrally
241 \emph{after} a push, to be sure all is well. The advantage of this
242 approach is that it does not impose a limit on the rate at which the
243 repository can accept changes.
245 \section{A short tutorial on using hooks}
246 \label{sec:hook:simple}
248 It is easy to write a Mercurial hook. Let's start with a hook that
249 runs when you finish a \hgcmd{commit}, and simply prints the hash of
250 the changeset you just created. The hook is called \hook{commit}.
252 \begin{figure}[ht]
253 \interaction{hook.simple.init}
254 \caption{A simple hook that runs when a changeset is committed}
255 \label{ex:hook:init}
256 \end{figure}
258 All hooks follow the pattern in example~\ref{ex:hook:init}. You add
259 an entry to the \rcsection{hooks} section of your \hgrc. On the left
260 is the name of the event to trigger on; on the right is the action to
261 take. As you can see, you can run an arbitrary shell command in a
262 hook. Mercurial passes extra information to the hook using
263 environment variables (look for \envar{HG\_NODE} in the example).
265 \subsection{Performing multiple actions per event}
267 Quite often, you will want to define more than one hook for a
268 particular kind of event, as shown in example~\ref{ex:hook:ext}.
269 Mercurial lets you do this by adding an \emph{extension} to the end of
270 a hook's name. You extend a hook's name by giving the name of the
271 hook, followed by a full stop (the ``\texttt{.}'' character), followed
272 by some more text of your choosing. For example, Mercurial will run
273 both \texttt{commit.foo} and \texttt{commit.bar} when the
274 \texttt{commit} event occurs.
276 \begin{figure}[ht]
277 \interaction{hook.simple.ext}
278 \caption{Defining a second \hook{commit} hook}
279 \label{ex:hook:ext}
280 \end{figure}
282 To give a well-defined order of execution when there are multiple
283 hooks defined for an event, Mercurial sorts hooks by extension, and
284 executes the hook commands in this sorted order. In the above
285 example, it will execute \texttt{commit.bar} before
286 \texttt{commit.foo}, and \texttt{commit} before both.
288 It is a good idea to use a somewhat descriptive extension when you
289 define a new hook. This will help you to remember what the hook was
290 for. If the hook fails, you'll get an error message that contains the
291 hook name and extension, so using a descriptive extension could give
292 you an immediate hint as to why the hook failed (see
293 section~\ref{sec:hook:perm} for an example).
295 \subsection{Controlling whether an activity can proceed}
296 \label{sec:hook:perm}
298 In our earlier examples, we used the \hook{commit} hook, which is
299 run after a commit has completed. This is one of several Mercurial
300 hooks that run after an activity finishes. Such hooks have no way of
301 influencing the activity itself.
303 Mercurial defines a number of events that occur before an activity
304 starts; or after it starts, but before it finishes. Hooks that
305 trigger on these events have the added ability to choose whether the
306 activity can continue, or will abort.
308 The \hook{pretxncommit} hook runs after a commit has all but
309 completed. In other words, the metadata representing the changeset
310 has been written out to disk, but the transaction has not yet been
311 allowed to complete. The \hook{pretxncommit} hook has the ability to
312 decide whether the transaction can complete, or must be rolled back.
314 If the \hook{pretxncommit} hook exits with a status code of zero, the
315 transaction is allowed to complete; the commit finishes; and the
316 \hook{commit} hook is run. If the \hook{pretxncommit} hook exits with
317 a non-zero status code, the transaction is rolled back; the metadata
318 representing the changeset is erased; and the \hook{commit} hook is
319 not run.
321 \begin{figure}[ht]
322 \interaction{hook.simple.pretxncommit}
323 \caption{Using the \hook{pretxncommit} hook to control commits}
324 \label{ex:hook:pretxncommit}
325 \end{figure}
327 The hook in example~\ref{ex:hook:pretxncommit} checks that a commit
328 comment contains a bug ID. If it does, the commit can complete. If
329 not, the commit is rolled back.
331 \section{Writing your own hooks}
333 When you are writing a hook, you might find it useful to run Mercurial
334 either with the \hggopt{-v} option, or the \rcitem{ui}{verbose} config
335 item set to ``true''. When you do so, Mercurial will print a message
336 before it calls each hook.
338 \subsection{Choosing how your hook should run}
339 \label{sec:hook:lang}
341 You can write a hook either as a normal program---typically a shell
342 script---or as a Python function that is executed within the Mercurial
343 process.
345 Writing a hook as an external program has the advantage that it
346 requires no knowledge of Mercurial's internals. You can call normal
347 Mercurial commands to get any added information you need. The
348 trade-off is that external hooks are slower than in-process hooks.
350 An in-process Python hook has complete access to the Mercurial API,
351 and does not ``shell out'' to another process, so it is inherently
352 faster than an external hook. It is also easier to obtain much of the
353 information that a hook requires by using the Mercurial API than by
354 running Mercurial commands.
356 If you are comfortable with Python, or require high performance,
357 writing your hooks in Python may be a good choice. However, when you
358 have a straightforward hook to write and you don't need to care about
359 performance (probably the majority of hooks), a shell script is
360 perfectly fine.
362 \subsection{Hook parameters}
363 \label{sec:hook:param}
365 Mercurial calls each hook with a set of well-defined parameters. In
366 Python, a parameter is passed as a keyword argument to your hook
367 function. For an external program, a parameter is passed as an
368 environment variable.
370 Whether your hook is written in Python or as a shell script, the
371 hook-specific parameter names and values will be the same. A boolean
372 parameter will be represented as a boolean value in Python, but as the
373 number 1 (for ``true'') or 0 (for ``false'') as an environment
374 variable for an external hook. If a hook parameter is named
375 \texttt{foo}, the keyword argument for a Python hook will also be
376 named \texttt{foo}, while the environment variable for an external
377 hook will be named \texttt{HG\_FOO}.
379 \subsection{Hook return values and activity control}
381 A hook that executes successfully must exit with a status of zero if
382 external, or return boolean ``false'' if in-process. Failure is
383 indicated with a non-zero exit status from an external hook, or an
384 in-process hook returning boolean ``true''. If an in-process hook
385 raises an exception, the hook is considered to have failed.
387 For a hook that controls whether an activity can proceed, zero/false
388 means ``allow'', while non-zero/true/exception means ``deny''.
390 \subsection{Writing an external hook}
392 When you define an external hook in your \hgrc\ and the hook is run,
393 its value is passed to your shell, which interprets it. This means
394 that you can use normal shell constructs in the body of the hook.
396 An executable hook is always run with its current directory set to a
397 repository's root directory.
399 Each hook parameter is passed in as an environment variable; the name
400 is upper-cased, and prefixed with the string ``\texttt{HG\_}''.
402 With the exception of hook parameters, Mercurial does not set or
403 modify any environment variables when running a hook. This is useful
404 to remember if you are writing a site-wide hook that may be run by a
405 number of different users with differing environment variables set.
406 In multi-user situations, you should not rely on environment variables
407 being set to the values you have in your environment when testing the
408 hook.
410 \subsection{Telling Mercurial to use an in-process hook}
412 The \hgrc\ syntax for defining an in-process hook is slightly
413 different than for an executable hook. The value of the hook must
414 start with the text ``\texttt{python:}'', and continue with the
415 fully-qualified name of a callable object to use as the hook's value.
417 The module in which a hook lives is automatically imported when a hook
418 is run. So long as you have the module name and \envar{PYTHONPATH}
419 right, it should ``just work''.
421 The following \hgrc\ example snippet illustrates the syntax and
422 meaning of the notions we just described.
423 \begin{codesample2}
424 [hooks]
425 commit.example = python:mymodule.submodule.myhook
426 \end{codesample2}
427 When Mercurial runs the \texttt{commit.example} hook, it imports
428 \texttt{mymodule.submodule}, looks for the callable object named
429 \texttt{myhook}, and calls it.
431 \subsection{Writing an in-process hook}
433 The simplest in-process hook does nothing, but illustrates the basic
434 shape of the hook API:
435 \begin{codesample2}
436 def myhook(ui, repo, **kwargs):
437 pass
438 \end{codesample2}
439 The first argument to a Python hook is always a
440 \pymodclass{mercurial.ui}{ui} object. The second is a repository object;
441 at the moment, it is always an instance of
442 \pymodclass{mercurial.localrepo}{localrepository}. Following these two
443 arguments are other keyword arguments. Which ones are passed in
444 depends on the hook being called, but a hook can ignore arguments it
445 doesn't care about by dropping them into a keyword argument dict, as
446 with \texttt{**kwargs} above.
448 \section{Some hook examples}
450 \subsection{Writing meaningful commit messages}
452 It's hard to imagine a useful commit message being very short. The
453 simple \hook{pretxncommit} hook of figure~\ref{ex:hook:msglen.go}
454 will prevent you from committing a changeset with a message that is
455 less than ten bytes long.
457 \begin{figure}[ht]
458 \interaction{hook.msglen.go}
459 \caption{A hook that forbids overly short commit messages}
460 \label{ex:hook:msglen.go}
461 \end{figure}
463 \subsection{Checking for trailing whitespace}
465 An interesting use of a commit-related hook is to help you to write
466 cleaner code. A simple example of ``cleaner code'' is the dictum that
467 a change should not add any new lines of text that contain ``trailing
468 whitespace''. Trailing whitespace is a series of space and tab
469 characters at the end of a line of text. In most cases, trailing
470 whitespace is unnecessary, invisible noise, but it is occasionally
471 problematic, and people often prefer to get rid of it.
473 You can use either the \hook{precommit} or \hook{pretxncommit} hook to
474 tell whether you have a trailing whitespace problem. If you use the
475 \hook{precommit} hook, the hook will not know which files you are
476 committing, so it will have to check every modified file in the
477 repository for trailing white space. If you want to commit a change
478 to just the file \filename{foo}, but the file \filename{bar} contains
479 trailing whitespace, doing a check in the \hook{precommit} hook will
480 prevent you from committing \filename{foo} due to the problem with
481 \filename{bar}. This doesn't seem right.
483 Should you choose the \hook{pretxncommit} hook, the check won't occur
484 until just before the transaction for the commit completes. This will
485 allow you to check for problems only the exact files that are being
486 committed. However, if you entered the commit message interactively
487 and the hook fails, the transaction will roll back; you'll have to
488 re-enter the commit message after you fix the trailing whitespace and
489 run \hgcmd{commit} again.
491 \begin{figure}[ht]
492 \interaction{hook.ws.simple}
493 \caption{A simple hook that checks for trailing whitespace}
494 \label{ex:hook:ws.simple}
495 \end{figure}
497 Figure~\ref{ex:hook:ws.simple} introduces a simple \hook{pretxncommit}
498 hook that checks for trailing whitespace. This hook is short, but not
499 very helpful. It exits with an error status if a change adds a line
500 with trailing whitespace to any file, but does not print any
501 information that might help us to identify the offending file or
502 line. It also has the nice property of not paying attention to
503 unmodified lines; only lines that introduce new trailing whitespace
504 cause problems.
506 \begin{figure}[ht]
507 \interaction{hook.ws.better}
508 \caption{A better trailing whitespace hook}
509 \label{ex:hook:ws.better}
510 \end{figure}
512 The example of figure~\ref{ex:hook:ws.better} is much more complex,
513 but also more useful. It parses a unified diff to see if any lines
514 add trailing whitespace, and prints the name of the file and the line
515 number of each such occurrence. Even better, if the change adds
516 trailing whitespace, this hook saves the commit comment and prints the
517 name of the save file before exiting and telling Mercurial to roll the
518 transaction back, so you can use
519 \hgcmdargs{commit}{\hgopt{commit}{-l}~\emph{filename}} to reuse the
520 saved commit message once you've corrected the problem.
522 As a final aside, note in figure~\ref{ex:hook:ws.better} the use of
523 \command{perl}'s in-place editing feature to get rid of trailing
524 whitespace from a file. This is concise and useful enough that I will
525 reproduce it here.
526 \begin{codesample2}
527 perl -pi -e 's,\\s+\$,,' filename
528 \end{codesample2}
530 \section{Bundled hooks}
532 Mercurial ships with several bundled hooks. You can find them in the
533 \dirname{hgext} directory of a Mercurial source tree. If you are
534 using a Mercurial binary package, the hooks will be located in the
535 \dirname{hgext} directory of wherever your package installer put
536 Mercurial.
538 \subsection{\hgext{acl}---access control for parts of a repository}
540 The \hgext{acl} extension lets you control which remote users are
541 allowed to push changesets to a networked server. You can protect any
542 portion of a repository (including the entire repo), so that a
543 specific remote user can push changes that do not affect the protected
544 portion.
546 This extension implements access control based on the identity of the
547 user performing a push, \emph{not} on who committed the changesets
548 they're pushing. It makes sense to use this hook only if you have a
549 locked-down server environment that authenticates remote users, and
550 you want to be sure that only specific users are allowed to push
551 changes to that server.
553 \subsubsection{Configuring the \hook{acl} hook}
555 In order to manage incoming changesets, the \hgext{acl} hook must be
556 used as a \hook{pretxnchangegroup} hook. This lets it see which files
557 are modified by each incoming changeset, and roll back a group of
558 changesets if they modify ``forbidden'' files. Example:
559 \begin{codesample2}
560 [hooks]
561 pretxnchangegroup.acl = python:hgext.acl.hook
562 \end{codesample2}
564 The \hgext{acl} extension is configured using three sections.
566 The \rcsection{acl} section has only one entry, \rcitem{acl}{sources},
567 which lists the sources of incoming changesets that the hook should
568 pay attention to. You don't normally need to configure this section.
569 \begin{itemize}
570 \item[\rcitem{acl}{serve}] Control incoming changesets that are arriving
571 from a remote repository over http or ssh. This is the default
572 value of \rcitem{acl}{sources}, and usually the only setting you'll
573 need for this configuration item.
574 \item[\rcitem{acl}{pull}] Control incoming changesets that are
575 arriving via a pull from a local repository.
576 \item[\rcitem{acl}{push}] Control incoming changesets that are
577 arriving via a push from a local repository.
578 \item[\rcitem{acl}{bundle}] Control incoming changesets that are
579 arriving from another repository via a bundle.
580 \end{itemize}
582 The \rcsection{acl.allow} section controls the users that are allowed to
583 add changesets to the repository. If this section is not present, all
584 users that are not explicitly denied are allowed. If this section is
585 present, all users that are not explicitly allowed are denied (so an
586 empty section means that all users are denied).
588 The \rcsection{acl.deny} section determines which users are denied
589 from adding changesets to the repository. If this section is not
590 present or is empty, no users are denied.
592 The syntaxes for the \rcsection{acl.allow} and \rcsection{acl.deny}
593 sections are identical. On the left of each entry is a glob pattern
594 that matches files or directories, relative to the root of the
595 repository; on the right, a user name.
597 In the following example, the user \texttt{docwriter} can only push
598 changes to the \dirname{docs} subtree of the repository, while
599 \texttt{intern} can push changes to any file or directory except
600 \dirname{source/sensitive}.
601 \begin{codesample2}
602 [acl.allow]
603 docs/** = docwriter
605 [acl.deny]
606 source/sensitive/** = intern
607 \end{codesample2}
609 \subsubsection{Testing and troubleshooting}
611 If you want to test the \hgext{acl} hook, run it with Mercurial's
612 debugging output enabled. Since you'll probably be running it on a
613 server where it's not convenient (or sometimes possible) to pass in
614 the \hggopt{--debug} option, don't forget that you can enable
615 debugging output in your \hgrc:
616 \begin{codesample2}
617 [ui]
618 debug = true
619 \end{codesample2}
620 With this enabled, the \hgext{acl} hook will print enough information
621 to let you figure out why it is allowing or forbidding pushes from
622 specific users.
624 \subsection{\hgext{bugzilla}---integration with Bugzilla}
626 The \hgext{bugzilla} extension adds a comment to a Bugzilla bug
627 whenever it finds a reference to that bug ID in a commit comment. You
628 can install this hook on a shared server, so that any time a remote
629 user pushes changes to this server, the hook gets run.
631 It adds a comment to the bug that looks like this (you can configure
632 the contents of the comment---see below):
633 \begin{codesample2}
634 Changeset aad8b264143a, made by Joe User <joe.user@domain.com> in
635 the frobnitz repository, refers to this bug.
637 For complete details, see
638 http://hg.domain.com/frobnitz?cmd=changeset;node=aad8b264143a
640 Changeset description:
641 Fix bug 10483 by guarding against some NULL pointers
642 \end{codesample2}
643 The value of this hook is that it automates the process of updating a
644 bug any time a changeset refers to it. If you configure the hook
645 properly, it makes it easy for people to browse straight from a
646 Bugzilla bug to a changeset that refers to that bug.
648 You can use the code in this hook as a starting point for some more
649 exotic Bugzilla integration recipes. Here are a few possibilities:
650 \begin{itemize}
651 \item Require that every changeset pushed to the server have a valid
652 bug~ID in its commit comment. In this case, you'd want to configure
653 the hook as a \hook{pretxncommit} hook. This would allow the hook
654 to reject changes that didn't contain bug IDs.
655 \item Allow incoming changesets to automatically modify the
656 \emph{state} of a bug, as well as simply adding a comment. For
657 example, the hook could recognise the string ``fixed bug 31337'' as
658 indicating that it should update the state of bug 31337 to
659 ``requires testing''.
660 \end{itemize}
662 \subsubsection{Configuring the \hook{bugzilla} hook}
663 \label{sec:hook:bugzilla:config}
665 You should configure this hook in your server's \hgrc\ as an
666 \hook{incoming} hook, for example as follows:
667 \begin{codesample2}
668 [hooks]
669 incoming.bugzilla = python:hgext.bugzilla.hook
670 \end{codesample2}
672 Because of the specialised nature of this hook, and because Bugzilla
673 was not written with this kind of integration in mind, configuring
674 this hook is a somewhat involved process.
676 Before you begin, you must install the MySQL bindings for Python on
677 the host(s) where you'll be running the hook. If this is not
678 available as a binary package for your system, you can download it
679 from~\cite{web:mysql-python}.
681 Configuration information for this hook lives in the
682 \rcsection{bugzilla} section of your \hgrc.
683 \begin{itemize}
684 \item[\rcitem{bugzilla}{version}] The version of Bugzilla installed on
685 the server. The database schema that Bugzilla uses changes
686 occasionally, so this hook has to know exactly which schema to use.
687 At the moment, the only version supported is \texttt{2.16}.
688 \item[\rcitem{bugzilla}{host}] The hostname of the MySQL server that
689 stores your Bugzilla data. The database must be configured to allow
690 connections from whatever host you are running the \hook{bugzilla}
691 hook on.
692 \item[\rcitem{bugzilla}{user}] The username with which to connect to
693 the MySQL server. The database must be configured to allow this
694 user to connect from whatever host you are running the
695 \hook{bugzilla} hook on. This user must be able to access and
696 modify Bugzilla tables. The default value of this item is
697 \texttt{bugs}, which is the standard name of the Bugzilla user in a
698 MySQL database.
699 \item[\rcitem{bugzilla}{password}] The MySQL password for the user you
700 configured above. This is stored as plain text, so you should make
701 sure that unauthorised users cannot read the \hgrc\ file where you
702 store this information.
703 \item[\rcitem{bugzilla}{db}] The name of the Bugzilla database on the
704 MySQL server. The default value of this item is \texttt{bugs},
705 which is the standard name of the MySQL database where Bugzilla
706 stores its data.
707 \item[\rcitem{bugzilla}{notify}] If you want Bugzilla to send out a
708 notification email to subscribers after this hook has added a
709 comment to a bug, you will need this hook to run a command whenever
710 it updates the database. The command to run depends on where you
711 have installed Bugzilla, but it will typically look something like
712 this, if you have Bugzilla installed in
713 \dirname{/var/www/html/bugzilla}:
714 \begin{codesample4}
715 cd /var/www/html/bugzilla && ./processmail %s nobody@nowhere.com
716 \end{codesample4}
717 The Bugzilla \texttt{processmail} program expects to be given a
718 bug~ID (the hook replaces ``\texttt{\%s}'' with the bug~ID) and an
719 email address. It also expects to be able to write to some files in
720 the directory that it runs in. If Bugzilla and this hook are not
721 installed on the same machine, you will need to find a way to run
722 \texttt{processmail} on the server where Bugzilla is installed.
723 \end{itemize}
725 \subsubsection{Mapping committer names to Bugzilla user names}
727 By default, the \hgext{bugzilla} hook tries to use the email address
728 of a changeset's committer as the Bugzilla user name with which to
729 update a bug. If this does not suit your needs, you can map committer
730 email addresses to Bugzilla user names using a \rcsection{usermap}
731 section.
733 Each item in the \rcsection{usermap} section contains an email address
734 on the left, and a Bugzilla user name on the right.
735 \begin{codesample2}
736 [usermap]
737 jane.user@example.com = jane
738 \end{codesample2}
739 You can either keep the \rcsection{usermap} data in a normal \hgrc, or
740 tell the \hgext{bugzilla} hook to read the information from an
741 external \filename{usermap} file. In the latter case, you can store
742 \filename{usermap} data by itself in (for example) a user-modifiable
743 repository. This makes it possible to let your users maintain their
744 own \rcitem{bugzilla}{usermap} entries. The main \hgrc\ file might
745 look like this:
746 \begin{codesample2}
747 # regular hgrc file refers to external usermap file
748 [bugzilla]
749 usermap = /home/hg/repos/userdata/bugzilla-usermap.conf
750 \end{codesample2}
751 While the \filename{usermap} file that it refers to might look like
752 this:
753 \begin{codesample2}
754 # bugzilla-usermap.conf - inside a hg repository
755 [usermap]
756 stephanie@example.com = steph
757 \end{codesample2}
759 \subsubsection{Configuring the text that gets added to a bug}
761 You can configure the text that this hook adds as a comment; you
762 specify it in the form of a Mercurial template. Several \hgrc\
763 entries (still in the \rcsection{bugzilla} section) control this
764 behaviour.
765 \begin{itemize}
766 \item[\texttt{strip}] The number of leading path elements to strip
767 from a repository's path name to construct a partial path for a URL.
768 For example, if the repositories on your server live under
769 \dirname{/home/hg/repos}, and you have a repository whose path is
770 \dirname{/home/hg/repos/app/tests}, then setting \texttt{strip} to
771 \texttt{4} will give a partial path of \dirname{app/tests}. The
772 hook will make this partial path available when expanding a
773 template, as \texttt{webroot}.
774 \item[\texttt{template}] The text of the template to use. In addition
775 to the usual changeset-related variables, this template can use
776 \texttt{hgweb} (the value of the \texttt{hgweb} configuration item
777 above) and \texttt{webroot} (the path constructed using
778 \texttt{strip} above).
779 \end{itemize}
781 In addition, you can add a \rcitem{web}{baseurl} item to the
782 \rcsection{web} section of your \hgrc. The \hgext{bugzilla} hook will
783 make this available when expanding a template, as the base string to
784 use when constructing a URL that will let users browse from a Bugzilla
785 comment to view a changeset. Example:
786 \begin{codesample2}
787 [web]
788 baseurl = http://hg.domain.com/
789 \end{codesample2}
791 Here is an example set of \hgext{bugzilla} hook config information.
792 \begin{codesample2}
793 [bugzilla]
794 host = bugzilla.example.com
795 password = mypassword
796 version = 2.16
797 # server-side repos live in /home/hg/repos, so strip 4 leading
798 # separators
799 strip = 4
800 hgweb = http://hg.example.com/
801 usermap = /home/hg/repos/notify/bugzilla.conf
802 template = Changeset \{node|short\}, made by \{author\} in the \{webroot\}
803 repo, refers to this bug.\\nFor complete details, see
804 \{hgweb\}\{webroot\}?cmd=changeset;node=\{node|short\}\\nChangeset
805 description:\\n\\t\{desc|tabindent\}
806 \end{codesample2}
808 \subsubsection{Testing and troubleshooting}
810 The most common problems with configuring the \hgext{bugzilla} hook
811 relate to running Bugzilla's \filename{processmail} script and mapping
812 committer names to user names.
814 Recall from section~\ref{sec:hook:bugzilla:config} above that the user
815 that runs the Mercurial process on the server is also the one that
816 will run the \filename{processmail} script. The
817 \filename{processmail} script sometimes causes Bugzilla to write to
818 files in its configuration directory, and Bugzilla's configuration
819 files are usually owned by the user that your web server runs under.
821 You can cause \filename{processmail} to be run with the suitable
822 user's identity using the \command{sudo} command. Here is an example
823 entry for a \filename{sudoers} file.
824 \begin{codesample2}
825 hg_user = (httpd_user) NOPASSWD: /var/www/html/bugzilla/processmail-wrapper %s
826 \end{codesample2}
827 This allows the \texttt{hg\_user} user to run a
828 \filename{processmail-wrapper} program under the identity of
829 \texttt{httpd\_user}.
831 This indirection through a wrapper script is necessary, because
832 \filename{processmail} expects to be run with its current directory
833 set to wherever you installed Bugzilla; you can't specify that kind of
834 constraint in a \filename{sudoers} file. The contents of the wrapper
835 script are simple:
836 \begin{codesample2}
837 #!/bin/sh
838 cd `dirname $0` && ./processmail "$1" nobody@example.com
839 \end{codesample2}
840 It doesn't seem to matter what email address you pass to
841 \filename{processmail}.
843 If your \rcsection{usermap} is not set up correctly, users will see an
844 error message from the \hgext{bugzilla} hook when they push changes
845 to the server. The error message will look like this:
846 \begin{codesample2}
847 cannot find bugzilla user id for john.q.public@example.com
848 \end{codesample2}
849 What this means is that the committer's address,
850 \texttt{john.q.public@example.com}, is not a valid Bugzilla user name,
851 nor does it have an entry in your \rcsection{usermap} that maps it to
852 a valid Bugzilla user name.
854 \subsection{\hgext{notify}---send email notifications}
856 Although Mercurial's built-in web server provides RSS feeds of changes
857 in every repository, many people prefer to receive change
858 notifications via email. The \hgext{notify} hook lets you send out
859 notifications to a set of email addresses whenever changesets arrive
860 that those subscribers are interested in.
862 As with the \hgext{bugzilla} hook, the \hgext{notify} hook is
863 template-driven, so you can customise the contents of the notification
864 messages that it sends.
866 By default, the \hgext{notify} hook includes a diff of every changeset
867 that it sends out; you can limit the size of the diff, or turn this
868 feature off entirely. It is useful for letting subscribers review
869 changes immediately, rather than clicking to follow a URL.
871 \subsubsection{Configuring the \hgext{notify} hook}
873 You can set up the \hgext{notify} hook to send one email message per
874 incoming changeset, or one per incoming group of changesets (all those
875 that arrived in a single pull or push).
876 \begin{codesample2}
877 [hooks]
878 # send one email per group of changes
879 changegroup.notify = python:hgext.notify.hook
880 # send one email per change
881 incoming.notify = python:hgext.notify.hook
882 \end{codesample2}
884 Configuration information for this hook lives in the
885 \rcsection{notify} section of a \hgrc\ file.
886 \begin{itemize}
887 \item[\rcitem{notify}{test}] By default, this hook does not send out
888 email at all; instead, it prints the message that it \emph{would}
889 send. Set this item to \texttt{false} to allow email to be sent.
890 The reason that sending of email is turned off by default is that it
891 takes several tries to configure this extension exactly as you would
892 like, and it would be bad form to spam subscribers with a number of
893 ``broken'' notifications while you debug your configuration.
894 \item[\rcitem{notify}{config}] The path to a configuration file that
895 contains subscription information. This is kept separate from the
896 main \hgrc\ so that you can maintain it in a repository of its own.
897 People can then clone that repository, update their subscriptions,
898 and push the changes back to your server.
899 \item[\rcitem{notify}{strip}] The number of leading path separator
900 characters to strip from a repository's path, when deciding whether
901 a repository has subscribers. For example, if the repositories on
902 your server live in \dirname{/home/hg/repos}, and \hgext{notify} is
903 considering a repository named \dirname{/home/hg/repos/shared/test},
904 setting \rcitem{notify}{strip} to \texttt{4} will cause
905 \hgext{notify} to trim the path it considers down to
906 \dirname{shared/test}, and it will match subscribers against that.
907 \item[\rcitem{notify}{template}] The template text to use when sending
908 messages. This specifies both the contents of the message header
909 and its body.
910 \item[\rcitem{notify}{maxdiff}] The maximum number of lines of diff
911 data to append to the end of a message. If a diff is longer than
912 this, it is truncated. By default, this is set to 300. Set this to
913 \texttt{0} to omit diffs from notification emails.
914 \item[\rcitem{notify}{sources}] A list of sources of changesets to
915 consider. This lets you limit \hgext{notify} to only sending out
916 email about changes that remote users pushed into this repository
917 via a server, for example. See section~\ref{sec:hook:sources} for
918 the sources you can specify here.
919 \end{itemize}
921 If you set the \rcitem{web}{baseurl} item in the \rcsection{web}
922 section, you can use it in a template; it will be available as
923 \texttt{webroot}.
925 Here is an example set of \hgext{notify} configuration information.
926 \begin{codesample2}
927 [notify]
928 # really send email
929 test = false
930 # subscriber data lives in the notify repo
931 config = /home/hg/repos/notify/notify.conf
932 # repos live in /home/hg/repos on server, so strip 4 "/" chars
933 strip = 4
934 template = X-Hg-Repo: \{webroot\}
935 Subject: \{webroot\}: \{desc|firstline|strip\}
936 From: \{author\}
938 changeset \{node|short\} in \{root\}
939 details: \{baseurl\}\{webroot\}?cmd=changeset;node=\{node|short\}
940 description:
941 \{desc|tabindent|strip\}
943 [web]
944 baseurl = http://hg.example.com/
945 \end{codesample2}
947 This will produce a message that looks like the following:
948 \begin{codesample2}
949 X-Hg-Repo: tests/slave
950 Subject: tests/slave: Handle error case when slave has no buffers
951 Date: Wed, 2 Aug 2006 15:25:46 -0700 (PDT)
953 changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave
954 details: http://hg.example.com/tests/slave?cmd=changeset;node=3cba9bfe74b5
955 description:
956 Handle error case when slave has no buffers
957 diffs (54 lines):
959 diff -r 9d95df7cf2ad -r 3cba9bfe74b5 include/tests.h
960 --- a/include/tests.h Wed Aug 02 15:19:52 2006 -0700
961 +++ b/include/tests.h Wed Aug 02 15:25:26 2006 -0700
962 @@ -212,6 +212,15 @@ static __inline__ void test_headers(void *h)
963 [...snip...]
964 \end{codesample2}
966 \subsubsection{Testing and troubleshooting}
968 Do not forget that by default, the \hgext{notify} extension \emph{will
969 not send any mail} until you explicitly configure it to do so, by
970 setting \rcitem{notify}{test} to \texttt{false}. Until you do that,
971 it simply prints the message it \emph{would} send.
973 \section{Information for writers of hooks}
974 \label{sec:hook:ref}
976 \subsection{In-process hook execution}
978 An in-process hook is called with arguments of the following form:
979 \begin{codesample2}
980 def myhook(ui, repo, **kwargs):
981 pass
982 \end{codesample2}
983 The \texttt{ui} parameter is a \pymodclass{mercurial.ui}{ui} object.
984 The \texttt{repo} parameter is a
985 \pymodclass{mercurial.localrepo}{localrepository} object. The
986 names and values of the \texttt{**kwargs} parameters depend on the
987 hook being invoked, with the following common features:
988 \begin{itemize}
989 \item If a parameter is named \texttt{node} or
990 \texttt{parent\emph{N}}, it will contain a hexadecimal changeset ID.
991 The empty string is used to represent ``null changeset ID'' instead
992 of a string of zeroes.
993 \item If a parameter is named \texttt{url}, it will contain the URL of
994 a remote repository, if that can be determined.
995 \item Boolean-valued parameters are represented as Python
996 \texttt{bool} objects.
997 \end{itemize}
999 An in-process hook is called without a change to the process's working
1000 directory (unlike external hooks, which are run in the root of the
1001 repository). It must not change the process's working directory, or
1002 it will cause any calls it makes into the Mercurial API to fail.
1004 If a hook returns a boolean ``false'' value, it is considered to have
1005 succeeded. If it returns a boolean ``true'' value or raises an
1006 exception, it is considered to have failed. A useful way to think of
1007 the calling convention is ``tell me if you fail''.
1009 Note that changeset IDs are passed into Python hooks as hexadecimal
1010 strings, not the binary hashes that Mercurial's APIs normally use. To
1011 convert a hash from hex to binary, use the
1012 \pymodfunc{mercurial.node}{bin} function.
1014 \subsection{External hook execution}
1016 An external hook is passed to the shell of the user running Mercurial.
1017 Features of that shell, such as variable substitution and command
1018 redirection, are available. The hook is run in the root directory of
1019 the repository (unlike in-process hooks, which are run in the same
1020 directory that Mercurial was run in).
1022 Hook parameters are passed to the hook as environment variables. Each
1023 environment variable's name is converted in upper case and prefixed
1024 with the string ``\texttt{HG\_}''. For example, if the name of a
1025 parameter is ``\texttt{node}'', the name of the environment variable
1026 representing that parameter will be ``\texttt{HG\_NODE}''.
1028 A boolean parameter is represented as the string ``\texttt{1}'' for
1029 ``true'', ``\texttt{0}'' for ``false''. If an environment variable is
1030 named \envar{HG\_NODE}, \envar{HG\_PARENT1} or \envar{HG\_PARENT2}, it
1031 contains a changeset ID represented as a hexadecimal string. The
1032 empty string is used to represent ``null changeset ID'' instead of a
1033 string of zeroes. If an environment variable is named
1034 \envar{HG\_URL}, it will contain the URL of a remote repository, if
1035 that can be determined.
1037 If a hook exits with a status of zero, it is considered to have
1038 succeeded. If it exits with a non-zero status, it is considered to
1039 have failed.
1041 \subsection{Finding out where changesets come from}
1043 A hook that involves the transfer of changesets between a local
1044 repository and another may be able to find out information about the
1045 ``far side''. Mercurial knows \emph{how} changes are being
1046 transferred, and in many cases \emph{where} they are being transferred
1047 to or from.
1049 \subsubsection{Sources of changesets}
1050 \label{sec:hook:sources}
1052 Mercurial will tell a hook what means are, or were, used to transfer
1053 changesets between repositories. This is provided by Mercurial in a
1054 Python parameter named \texttt{source}, or an environment variable named
1055 \envar{HG\_SOURCE}.
1057 \begin{itemize}
1058 \item[\texttt{serve}] Changesets are transferred to or from a remote
1059 repository over http or ssh.
1060 \item[\texttt{pull}] Changesets are being transferred via a pull from
1061 one repository into another.
1062 \item[\texttt{push}] Changesets are being transferred via a push from
1063 one repository into another.
1064 \item[\texttt{bundle}] Changesets are being transferred to or from a
1065 bundle.
1066 \end{itemize}
1068 \subsubsection{Where changes are going---remote repository URLs}
1069 \label{sec:hook:url}
1071 When possible, Mercurial will tell a hook the location of the ``far
1072 side'' of an activity that transfers changeset data between
1073 repositories. This is provided by Mercurial in a Python parameter
1074 named \texttt{url}, or an environment variable named \envar{HG\_URL}.
1076 This information is not always known. If a hook is invoked in a
1077 repository that is being served via http or ssh, Mercurial cannot tell
1078 where the remote repository is, but it may know where the client is
1079 connecting from. In such cases, the URL will take one of the
1080 following forms:
1081 \begin{itemize}
1082 \item \texttt{remote:ssh:\emph{ip-address}}---remote ssh client, at
1083 the given IP address.
1084 \item \texttt{remote:http:\emph{ip-address}}---remote http client, at
1085 the given IP address. If the client is using SSL, this will be of
1086 the form \texttt{remote:https:\emph{ip-address}}.
1087 \item Empty---no information could be discovered about the remote
1088 client.
1089 \end{itemize}
1091 \section{Hook reference}
1093 \subsection{\hook{changegroup}---after remote changesets added}
1094 \label{sec:hook:changegroup}
1096 This hook is run after a group of pre-existing changesets has been
1097 added to the repository, for example via a \hgcmd{pull} or
1098 \hgcmd{unbundle}. This hook is run once per operation that added one
1099 or more changesets. This is in contrast to the \hook{incoming} hook,
1100 which is run once per changeset, regardless of whether the changesets
1101 arrive in a group.
1103 Some possible uses for this hook include kicking off an automated
1104 build or test of the added changesets, updating a bug database, or
1105 notifying subscribers that a repository contains new changes.
1107 Parameters to this hook:
1108 \begin{itemize}
1109 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1110 changeset in the group that was added. All changesets between this
1111 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
1112 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
1113 \item[\texttt{source}] A string. The source of these changes. See
1114 section~\ref{sec:hook:sources} for details.
1115 \item[\texttt{url}] A URL. The location of the remote repository, if
1116 known. See section~\ref{sec:hook:url} for more information.
1117 \end{itemize}
1119 See also: \hook{incoming} (section~\ref{sec:hook:incoming}),
1120 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}),
1121 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1123 \subsection{\hook{commit}---after a new changeset is created}
1124 \label{sec:hook:commit}
1126 This hook is run after a new changeset has been created.
1128 Parameters to this hook:
1129 \begin{itemize}
1130 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
1131 committed changeset.
1132 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1133 parent of the newly committed changeset.
1134 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1135 parent of the newly committed changeset.
1136 \end{itemize}
1138 See also: \hook{precommit} (section~\ref{sec:hook:precommit}),
1139 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
1141 \subsection{\hook{incoming}---after one remote changeset is added}
1142 \label{sec:hook:incoming}
1144 This hook is run after a pre-existing changeset has been added to the
1145 repository, for example via a \hgcmd{push}. If a group of changesets
1146 was added in a single operation, this hook is called once for each
1147 added changeset.
1149 You can use this hook for the same purposes as the \hook{changegroup}
1150 hook (section~\ref{sec:hook:changegroup}); it's simply more convenient
1151 sometimes to run a hook once per group of changesets, while other
1152 times it's handier once per changeset.
1154 Parameters to this hook:
1155 \begin{itemize}
1156 \item[\texttt{node}] A changeset ID. The ID of the newly added
1157 changeset.
1158 \item[\texttt{source}] A string. The source of these changes. See
1159 section~\ref{sec:hook:sources} for details.
1160 \item[\texttt{url}] A URL. The location of the remote repository, if
1161 known. See section~\ref{sec:hook:url} for more information.
1162 \end{itemize}
1164 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}) \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}), \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1166 \subsection{\hook{outgoing}---after changesets are propagated}
1167 \label{sec:hook:outgoing}
1169 This hook is run after a group of changesets has been propagated out
1170 of this repository, for example by a \hgcmd{push} or \hgcmd{bundle}
1171 command.
1173 One possible use for this hook is to notify administrators that
1174 changes have been pulled.
1176 Parameters to this hook:
1177 \begin{itemize}
1178 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1179 changeset of the group that was sent.
1180 \item[\texttt{source}] A string. The source of the of the operation
1181 (see section~\ref{sec:hook:sources}). If a remote client pulled
1182 changes from this repository, \texttt{source} will be
1183 \texttt{serve}. If the client that obtained changes from this
1184 repository was local, \texttt{source} will be \texttt{bundle},
1185 \texttt{pull}, or \texttt{push}, depending on the operation the
1186 client performed.
1187 \item[\texttt{url}] A URL. The location of the remote repository, if
1188 known. See section~\ref{sec:hook:url} for more information.
1189 \end{itemize}
1191 See also: \hook{preoutgoing} (section~\ref{sec:hook:preoutgoing})
1193 \subsection{\hook{prechangegroup}---before starting to add remote changesets}
1194 \label{sec:hook:prechangegroup}
1196 This controlling hook is run before Mercurial begins to add a group of
1197 changesets from another repository.
1199 This hook does not have any information about the changesets to be
1200 added, because it is run before transmission of those changesets is
1201 allowed to begin. If this hook fails, the changesets will not be
1202 transmitted.
1204 One use for this hook is to prevent external changes from being added
1205 to a repository. For example, you could use this to ``freeze'' a
1206 server-hosted branch temporarily or permanently so that users cannot
1207 push to it, while still allowing a local administrator to modify the
1208 repository.
1210 Parameters to this hook:
1211 \begin{itemize}
1212 \item[\texttt{source}] A string. The source of these changes. See
1213 section~\ref{sec:hook:sources} for details.
1214 \item[\texttt{url}] A URL. The location of the remote repository, if
1215 known. See section~\ref{sec:hook:url} for more information.
1216 \end{itemize}
1218 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
1219 \hook{incoming} (section~\ref{sec:hook:incoming}), ,
1220 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
1222 \subsection{\hook{precommit}---before starting to commit a changeset}
1223 \label{sec:hook:precommit}
1225 This hook is run before Mercurial begins to commit a new changeset.
1226 It is run before Mercurial has any of the metadata for the commit,
1227 such as the files to be committed, the commit message, or the commit
1228 date.
1230 One use for this hook is to disable the ability to commit new
1231 changesets, while still allowing incoming changesets. Another is to
1232 run a build or test, and only allow the commit to begin if the build
1233 or test succeeds.
1235 Parameters to this hook:
1236 \begin{itemize}
1237 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1238 parent of the working directory.
1239 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1240 parent of the working directory.
1241 \end{itemize}
1242 If the commit proceeds, the parents of the working directory will
1243 become the parents of the new changeset.
1245 See also: \hook{commit} (section~\ref{sec:hook:commit}),
1246 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
1248 \subsection{\hook{preoutgoing}---before starting to propagate changesets}
1249 \label{sec:hook:preoutgoing}
1251 This hook is invoked before Mercurial knows the identities of the
1252 changesets to be transmitted.
1254 One use for this hook is to prevent changes from being transmitted to
1255 another repository.
1257 Parameters to this hook:
1258 \begin{itemize}
1259 \item[\texttt{source}] A string. The source of the operation that is
1260 attempting to obtain changes from this repository (see
1261 section~\ref{sec:hook:sources}). See the documentation for the
1262 \texttt{source} parameter to the \hook{outgoing} hook, in
1263 section~\ref{sec:hook:outgoing}, for possible values of this
1264 parameter.
1265 \item[\texttt{url}] A URL. The location of the remote repository, if
1266 known. See section~\ref{sec:hook:url} for more information.
1267 \end{itemize}
1269 See also: \hook{outgoing} (section~\ref{sec:hook:outgoing})
1271 \subsection{\hook{pretag}---before tagging a changeset}
1272 \label{sec:hook:pretag}
1274 This controlling hook is run before a tag is created. If the hook
1275 succeeds, creation of the tag proceeds. If the hook fails, the tag is
1276 not created.
1278 Parameters to this hook:
1279 \begin{itemize}
1280 \item[\texttt{local}] A boolean. Whether the tag is local to this
1281 repository instance (i.e.~stored in \sfilename{.hg/localtags}) or
1282 managed by Mercurial (stored in \sfilename{.hgtags}).
1283 \item[\texttt{node}] A changeset ID. The ID of the changeset to be tagged.
1284 \item[\texttt{tag}] A string. The name of the tag to be created.
1285 \end{itemize}
1287 If the tag to be created is revision-controlled, the \hook{precommit}
1288 and \hook{pretxncommit} hooks (sections~\ref{sec:hook:commit}
1289 and~\ref{sec:hook:pretxncommit}) will also be run.
1291 See also: \hook{tag} (section~\ref{sec:hook:tag})
1293 \subsection{\hook{pretxnchangegroup}---before completing addition of
1294 remote changesets}
1295 \label{sec:hook:pretxnchangegroup}
1297 This controlling hook is run before a transaction---that manages the
1298 addition of a group of new changesets from outside the
1299 repository---completes. If the hook succeeds, the transaction
1300 completes, and all of the changesets become permanent within this
1301 repository. If the hook fails, the transaction is rolled back, and
1302 the data for the changesets is erased.
1304 This hook can access the metadata associated with the almost-added
1305 changesets, but it should not do anything permanent with this data.
1306 It must also not modify the working directory.
1308 While this hook is running, if other Mercurial processes access this
1309 repository, they will be able to see the almost-added changesets as if
1310 they are permanent. This may lead to race conditions if you do not
1311 take steps to avoid them.
1313 This hook can be used to automatically vet a group of changesets. If
1314 the hook fails, all of the changesets are ``rejected'' when the
1315 transaction rolls back.
1317 Parameters to this hook:
1318 \begin{itemize}
1319 \item[\texttt{node}] A changeset ID. The changeset ID of the first
1320 changeset in the group that was added. All changesets between this
1321 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
1322 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
1323 \item[\texttt{source}] A string. The source of these changes. See
1324 section~\ref{sec:hook:sources} for details.
1325 \item[\texttt{url}] A URL. The location of the remote repository, if
1326 known. See section~\ref{sec:hook:url} for more information.
1327 \end{itemize}
1329 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
1330 \hook{incoming} (section~\ref{sec:hook:incoming}),
1331 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup})
1333 \subsection{\hook{pretxncommit}---before completing commit of new changeset}
1334 \label{sec:hook:pretxncommit}
1336 This controlling hook is run before a transaction---that manages a new
1337 commit---completes. If the hook succeeds, the transaction completes
1338 and the changeset becomes permanent within this repository. If the
1339 hook fails, the transaction is rolled back, and the commit data is
1340 erased.
1342 This hook can access the metadata associated with the almost-new
1343 changeset, but it should not do anything permanent with this data. It
1344 must also not modify the working directory.
1346 While this hook is running, if other Mercurial processes access this
1347 repository, they will be able to see the almost-new changeset as if it
1348 is permanent. This may lead to race conditions if you do not take
1349 steps to avoid them.
1351 Parameters to this hook:
1352 \begin{itemize}
1353 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
1354 committed changeset.
1355 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
1356 parent of the newly committed changeset.
1357 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
1358 parent of the newly committed changeset.
1359 \end{itemize}
1361 See also: \hook{precommit} (section~\ref{sec:hook:precommit})
1363 \subsection{\hook{preupdate}---before updating or merging working directory}
1364 \label{sec:hook:preupdate}
1366 This controlling hook is run before an update or merge of the working
1367 directory begins. It is run only if Mercurial's normal pre-update
1368 checks determine that the update or merge can proceed. If the hook
1369 succeeds, the update or merge may proceed; if it fails, the update or
1370 merge does not start.
1372 Parameters to this hook:
1373 \begin{itemize}
1374 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
1375 working directory is to be updated to. If the working directory is
1376 being merged, it will not change this parent.
1377 \item[\texttt{parent2}] A changeset ID. Only set if the working
1378 directory is being merged. The ID of the revision that the working
1379 directory is being merged with.
1380 \end{itemize}
1382 See also: \hook{update} (section~\ref{sec:hook:update})
1384 \subsection{\hook{tag}---after tagging a changeset}
1385 \label{sec:hook:tag}
1387 This hook is run after a tag has been created.
1389 Parameters to this hook:
1390 \begin{itemize}
1391 \item[\texttt{local}] A boolean. Whether the new tag is local to this
1392 repository instance (i.e.~stored in \sfilename{.hg/localtags}) or
1393 managed by Mercurial (stored in \sfilename{.hgtags}).
1394 \item[\texttt{node}] A changeset ID. The ID of the changeset that was
1395 tagged.
1396 \item[\texttt{tag}] A string. The name of the tag that was created.
1397 \end{itemize}
1399 If the created tag is revision-controlled, the \hook{commit} hook
1400 (section~\ref{sec:hook:commit}) is run before this hook.
1402 See also: \hook{pretag} (section~\ref{sec:hook:pretag})
1404 \subsection{\hook{update}---after updating or merging working directory}
1405 \label{sec:hook:update}
1407 This hook is run after an update or merge of the working directory
1408 completes. Since a merge can fail (if the external \command{hgmerge}
1409 command fails to resolve conflicts in a file), this hook communicates
1410 whether the update or merge completed cleanly.
1412 \begin{itemize}
1413 \item[\texttt{error}] A boolean. Indicates whether the update or
1414 merge completed successfully.
1415 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
1416 working directory was updated to. If the working directory was
1417 merged, it will not have changed this parent.
1418 \item[\texttt{parent2}] A changeset ID. Only set if the working
1419 directory was merged. The ID of the revision that the working
1420 directory was merged with.
1421 \end{itemize}
1423 See also: \hook{preupdate} (section~\ref{sec:hook:preupdate})
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