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author	jerojasro@localhost
date	Mon Dec 01 21:53:26 2008 -0500 (2008-12-01)
parents	7e52f0cc4516
children	05bfbe50e7e4

rev	line source
jerojasro@435	1 \chapter{Manejo de eventos en repositorios con ganchos}
jerojasro@336	2 \label{chap:hook}
jerojasro@336	3
jerojasro@435	4 Mercurial ofrece un poderoso mecanismo para permitirle a usted
jerojasro@435	5 automatizar la ejecución de acciones en respuesta a eventos que
jerojasro@435	6 ocurran en un repositorio. En algunos casos, usted puede controlar
jerojasro@435	7 incluso la respuesta de Mercurial a dichos eventos.
jerojasro@435	8
jerojasro@435	9 Mercurial usa el término \emph{gancho} para identificar estas
jerojasro@435	10 acciones. Los ganchos son conocidos como ``disparadores'' en algunos
jerojasro@435	11 sistemas de control de revisiones, pero los dos nombres se refieren al
jerojasro@435	12 mismo concepto.
jerojasro@435	13
jerojasro@435	14 \section{Vistazo general de ganchos en Mercurial}
jerojasro@435	15
jerojasro@435	16 A continuación se encuentra una breve lista de los ganchos que
jerojasro@435	17 Mercurial soporta. Volveremos a cada uno de estos ganchos con más
jerojasro@435	18 detalle después, en la sección~\ref{sec:hook:ref}.
jerojasro@435	19
jerojasro@435	20 \begin{itemize}
jerojasro@435	21 \item[\small\hook{changegroup}] Es ejecutado luego de que un grupo de
jerojasro@435	22 conjuntos de cambios ha sido traído al repositorio desde algún
jerojasro@435	23 otro sitio.
jerojasro@435	24 \item[\small\hook{commit}] Es ejecutado después de la creación de
jerojasro@435	25 un conjunto de cambios en el repositorio local.
jerojasro@435	26 \item[\small\hook{incoming}] Es ejecutado una vez por cada conjunto de
jerojasro@435	27 cambios traído al repositorio desde otra ubicación. Note la
jerojasro@435	28 diferencia respecto al gancho \hook{changegroup}, que es ejecutado
jerojasro@435	29 una vez por cada \emph{grupo} de conjuntos de cambios que se
jerojasro@435	30 traiga.
jerojasro@435	31 \item[\small\hook{outgoing}] Es ejecutado luego de que un grupo de
jerojasro@435	32 conjuntos de cambios ha sido transmitido desde el repositorio.
jerojasro@435	33 \item[\small\hook{prechangegroup}] Es ejecutado antes de iniciar la
jerojasro@435	34 recepción de un grupo de conjuntos de cambios en el repositorio.
jerojasro@435	35 \item[\small\hook{precommit}] De control. Es ejecutado antes de
jerojasro@435	36 iniciar una consignación.
jerojasro@435	37 \item[\small\hook{preoutgoing}] De control. Es ejecutado antes de
jerojasro@435	38 iniciar la transmisión de un grupo de conjuntos de cambios desde
jerojasro@435	39 el repositorio.
jerojasro@435	40 \item[\small\hook{pretag}] De control. Es ejecutado antes de crear una
jerojasro@435	41 etiqueta.
jerojasro@435	42 \item[\small\hook{pretxnchangegroup}] De control. Es ejecutado después
jerojasro@435	43 de haber recibido un grupo de conjuntos de cambios en el
jerojasro@435	44 repositorio local, pero antes de que la transacción se complete y
jerojasro@435	45 los cambios sean permanentes dentro del repositorio.
jerojasro@435	46 \item[\small\hook{pretxncommit}] De control. Es ejecutado luego de la
jerojasro@435	47 creación de un conjunto de cambios en el repositorio local, pero
jerojasro@435	48 antes de que la transacción que hace permanente el cambio sea
jerojasro@435	49 completada.
jerojasro@435	50 \item[\small\hook{preupdate}] De control. Es ejecutado antes de
jerojasro@435	51 iniciar una actualización o fusión en el directorio de trabajo.
jerojasro@435	52 \item[\small\hook{tag}] Es ejecutado después de la creación de una
jerojasro@435	53 etiqueta.
jerojasro@435	54 \item[\small\hook{update}] Es ejecutado después de que termina una
jerojasro@435	55 actualización o una fusión.
jerojasro@435	56 \end{itemize}
jerojasro@435	57 Cada uno de los ganchos cuya descripción empieza con la frase
jerojasro@435	58 ``de control'' tiene la facultad de determinar si una actividad puede
jerojasro@435	59 continuar. Si el gancho se ejecuta con éxito, la actividad puede
jerojasro@435	60 continuar; si falla, o bien la actividad no es permitida, o se
jerojasro@435	61 deshacen los cambios que se puedan haber llevado a cabo, dependiendo
jerojasro@435	62 del gancho involucrado.
jerojasro@435	63
jerojasro@435	64 \section{Ganchos y seguridad}
jerojasro@435	65
jerojasro@435	66 \subsection{Los ganchos se ejecutan con sus privilegios de usuario}
jerojasro@435	67
jerojasro@435	68 Cuando usted ejecuta un comando de Mercurial en un repositorio, y el
jerojasro@435	69 comando causa la ejecución de un gancho, dicho gancho se ejecuta en
jerojasro@435	70 \emph{su} sistema, en \emph{su} cuenta de usuario, con \emph{sus}
jerojasro@435	71 privilegios. Ya que los ganchos son elementos arbitrarios de código
jerojasro@435	72 ejecutable, usted debería tratarlos con un nivel adecuado de
jerojasro@435	73 desconfianza. No instale un gancho a menos en que confíe en quien lo
jerojasro@435	74 creó y en lo que el gancho hace.
jerojasro@435	75
jerojasro@435	76 En algunos casos, usted puede estar expuesto a ganchos que usted no
jerojasro@435	77 %TODO acá introduzco algo de texto por mi cuenta, por claridad
jerojasro@435	78 instaló. Si usted usa Mercurial en un sistema extraño, tenga en cuenta
jerojasro@435	79 que Mercurial ejecutará los ganchos definidos en el fichero \hgrc.
jerojasro@435	80
jerojasro@435	81 Si está trabajando con un repositorio propiedad de otro usuario,
jerojasro@435	82 Mercurial podrá ejecutar los ganchos definidos en el repositorio de
jerojasro@435	83 dicho usuario, pero los ejecutará como ``usted''. Por ejemplo, si
jerojasro@435	84 usted jala (\hgcmd{pull}) desde ese repositorio, y el
jerojasro@435	85 \sfilename{.hg/hgrc} define un gancho saliente (\hook{outgoing}),
jerojasro@435	86 dicho gancho se ejecuta bajo su cuenta de usuario, aun cuando usted no
jerojasro@435	87 es el propietario del repositorio.
jerojasro@336	88
jerojasro@336	89 \begin{note}
jerojasro@435	90 Esto sólo aplica si usted está jalando desde un repositorio en un
jerojasro@435	91 sistema de ficheros local o de red. Si está jalando a través de http
jerojasro@435	92 o ssh, cualquier gancho saliente (\hook{outgoing}) se ejecutará bajo
jerojasro@435	93 la cuenta que está ejecutando el proceso servidor, en el servidor.
jerojasro@336	94 \end{note}
jerojasro@336	95
jerojasro@435	96 XXX Para ver qué ganchos han sido definidos en un repositorio, use el
jerojasro@435	97 comando \hgcmdargs{config}{hooks}. Si usted está trabajando en un
jerojasro@435	98 repositorio, pero comunicándose con otro que no le pertenece
jerojasro@435	99 (por ejemplo, usando \hgcmd{pull} o \hgcmd{incoming}), recuerde que
jerojasro@435	100 los ganchos que debe considerar son los del otro repositorio, no los
jerojasro@435	101 del suyo.
jerojasro@435	102
jerojasro@435	103 \subsection{Los ganchos no se propagan}
jerojasro@435	104
jerojasro@435	105 En Mercurial, no se hace control de revisiones de los ganchos, y no se
jerojasro@435	106 propagan cuando usted clona, o jala de, un repositorio. El motivo para
jerojasro@435	107 esto es simple: un gancho es código ejecutable arbitrario. Se ejecuta
jerojasro@435	108 bajo su identidad, con su nivel de privilegios, en su máquina.
jerojasro@435	109
jerojasro@435	110 Sería extremadamente descuidado de parte de cualquier sistema
jerojasro@435	111 distribuido de control de revisiones el implementar control de
jerojasro@435	112 revisiones para ganchos, ya que esto ofrecería maneras fácilmente
jerojasro@435	113 %TODO subvertir
jerojasro@435	114 aprovechables de subvertir las cuentas de los usuarios del sistema de
jerojasro@435	115 control de revisiones.
jerojasro@435	116
jerojasro@435	117 Ya que Mercurial no propaga los ganchos, si usted está colaborando con
jerojasro@435	118 otras personas en un proyecto común, no debería asumir que ellos están
jerojasro@435	119 usando los mismos ganchos para Mercurial que usted usa, o que los de
jerojasro@435	120 ellos están configurado correctamente. Usted debería documentar los
jerojasro@435	121 ganchos que usted espera que la gente use.
jerojasro@336	122
jerojasro@336	123 In a corporate intranet, this is somewhat easier to control, as you
jerojasro@336	124 can for example provide a ``standard'' installation of Mercurial on an
jerojasro@336	125 NFS filesystem, and use a site-wide \hgrc\ file to define hooks that
jerojasro@336	126 all users will see. However, this too has its limits; see below.
jerojasro@336	127
jerojasro@336	128 \subsection{Hooks can be overridden}
jerojasro@336	129
jerojasro@336	130 Mercurial allows you to override a hook definition by redefining the
jerojasro@336	131 hook. You can disable it by setting its value to the empty string, or
jerojasro@336	132 change its behaviour as you wish.
jerojasro@336	133
jerojasro@336	134 If you deploy a system-~or site-wide \hgrc\ file that defines some
jerojasro@336	135 hooks, you should thus understand that your users can disable or
jerojasro@336	136 override those hooks.
jerojasro@336	137
jerojasro@336	138 \subsection{Ensuring that critical hooks are run}
jerojasro@336	139
jerojasro@336	140 Sometimes you may want to enforce a policy that you do not want others
jerojasro@336	141 to be able to work around. For example, you may have a requirement
jerojasro@336	142 that every changeset must pass a rigorous set of tests. Defining this
jerojasro@336	143 requirement via a hook in a site-wide \hgrc\ won't work for remote
jerojasro@336	144 users on laptops, and of course local users can subvert it at will by
jerojasro@336	145 overriding the hook.
jerojasro@336	146
jerojasro@336	147 Instead, you can set up your policies for use of Mercurial so that
jerojasro@336	148 people are expected to propagate changes through a well-known
jerojasro@336	149 ``canonical'' server that you have locked down and configured
jerojasro@336	150 appropriately.
jerojasro@336	151
jerojasro@336	152 One way to do this is via a combination of social engineering and
jerojasro@336	153 technology. Set up a restricted-access account; users can push
jerojasro@336	154 changes over the network to repositories managed by this account, but
jerojasro@336	155 they cannot log into the account and run normal shell commands. In
jerojasro@336	156 this scenario, a user can commit a changeset that contains any old
jerojasro@336	157 garbage they want.
jerojasro@336	158
jerojasro@336	159 When someone pushes a changeset to the server that everyone pulls
jerojasro@336	160 from, the server will test the changeset before it accepts it as
jerojasro@336	161 permanent, and reject it if it fails to pass the test suite. If
jerojasro@336	162 people only pull changes from this filtering server, it will serve to
jerojasro@336	163 ensure that all changes that people pull have been automatically
jerojasro@336	164 vetted.
jerojasro@336	165
jerojasro@336	166 \section{Care with \texttt{pretxn} hooks in a shared-access repository}
jerojasro@336	167
jerojasro@336	168 If you want to use hooks to do some automated work in a repository
jerojasro@336	169 that a number of people have shared access to, you need to be careful
jerojasro@336	170 in how you do this.
jerojasro@336	171
jerojasro@336	172 Mercurial only locks a repository when it is writing to the
jerojasro@336	173 repository, and only the parts of Mercurial that write to the
jerojasro@336	174 repository pay attention to locks. Write locks are necessary to
jerojasro@336	175 prevent multiple simultaneous writers from scribbling on each other's
jerojasro@336	176 work, corrupting the repository.
jerojasro@336	177
jerojasro@336	178 Because Mercurial is careful with the order in which it reads and
jerojasro@336	179 writes data, it does not need to acquire a lock when it wants to read
jerojasro@336	180 data from the repository. The parts of Mercurial that read from the
jerojasro@336	181 repository never pay attention to locks. This lockless reading scheme
jerojasro@336	182 greatly increases performance and concurrency.
jerojasro@336	183
jerojasro@336	184 With great performance comes a trade-off, though, one which has the
jerojasro@336	185 potential to cause you trouble unless you're aware of it. To describe
jerojasro@336	186 this requires a little detail about how Mercurial adds changesets to a
jerojasro@336	187 repository and reads those changes.
jerojasro@336	188
jerojasro@336	189 When Mercurial \emph{writes} metadata, it writes it straight into the
jerojasro@336	190 destination file. It writes file data first, then manifest data
jerojasro@336	191 (which contains pointers to the new file data), then changelog data
jerojasro@336	192 (which contains pointers to the new manifest data). Before the first
jerojasro@336	193 write to each file, it stores a record of where the end of the file
jerojasro@336	194 was in its transaction log. If the transaction must be rolled back,
jerojasro@336	195 Mercurial simply truncates each file back to the size it was before the
jerojasro@336	196 transaction began.
jerojasro@336	197
jerojasro@336	198 When Mercurial \emph{reads} metadata, it reads the changelog first,
jerojasro@336	199 then everything else. Since a reader will only access parts of the
jerojasro@336	200 manifest or file metadata that it can see in the changelog, it can
jerojasro@336	201 never see partially written data.
jerojasro@336	202
jerojasro@336	203 Some controlling hooks (\hook{pretxncommit} and
jerojasro@336	204 \hook{pretxnchangegroup}) run when a transaction is almost complete.
jerojasro@336	205 All of the metadata has been written, but Mercurial can still roll the
jerojasro@336	206 transaction back and cause the newly-written data to disappear.
jerojasro@336	207
jerojasro@336	208 If one of these hooks runs for long, it opens a window of time during
jerojasro@336	209 which a reader can see the metadata for changesets that are not yet
jerojasro@336	210 permanent, and should not be thought of as ``really there''. The
jerojasro@336	211 longer the hook runs, the longer that window is open.
jerojasro@336	212
jerojasro@336	213 \subsection{The problem illustrated}
jerojasro@336	214
jerojasro@336	215 In principle, a good use for the \hook{pretxnchangegroup} hook would
jerojasro@336	216 be to automatically build and test incoming changes before they are
jerojasro@336	217 accepted into a central repository. This could let you guarantee that
jerojasro@336	218 nobody can push changes to this repository that ``break the build''.
jerojasro@336	219 But if a client can pull changes while they're being tested, the
jerojasro@336	220 usefulness of the test is zero; an unsuspecting someone can pull
jerojasro@336	221 untested changes, potentially breaking their build.
jerojasro@336	222
jerojasro@336	223 The safest technological answer to this challenge is to set up such a
jerojasro@336	224 ``gatekeeper'' repository as \emph{unidirectional}. Let it take
jerojasro@336	225 changes pushed in from the outside, but do not allow anyone to pull
jerojasro@336	226 changes from it (use the \hook{preoutgoing} hook to lock it down).
jerojasro@336	227 Configure a \hook{changegroup} hook so that if a build or test
jerojasro@336	228 succeeds, the hook will push the new changes out to another repository
jerojasro@336	229 that people \emph{can} pull from.
jerojasro@336	230
jerojasro@336	231 In practice, putting a centralised bottleneck like this in place is
jerojasro@336	232 not often a good idea, and transaction visibility has nothing to do
jerojasro@336	233 with the problem. As the size of a project---and the time it takes to
jerojasro@336	234 build and test---grows, you rapidly run into a wall with this ``try
jerojasro@336	235 before you buy'' approach, where you have more changesets to test than
jerojasro@336	236 time in which to deal with them. The inevitable result is frustration
jerojasro@336	237 on the part of all involved.
jerojasro@336	238
jerojasro@336	239 An approach that scales better is to get people to build and test
jerojasro@336	240 before they push, then run automated builds and tests centrally
jerojasro@336	241 \emph{after} a push, to be sure all is well. The advantage of this
jerojasro@336	242 approach is that it does not impose a limit on the rate at which the
jerojasro@336	243 repository can accept changes.
jerojasro@336	244
jerojasro@336	245 \section{A short tutorial on using hooks}
jerojasro@336	246 \label{sec:hook:simple}
jerojasro@336	247
jerojasro@336	248 It is easy to write a Mercurial hook. Let's start with a hook that
jerojasro@336	249 runs when you finish a \hgcmd{commit}, and simply prints the hash of
jerojasro@336	250 the changeset you just created. The hook is called \hook{commit}.
jerojasro@336	251
jerojasro@336	252 \begin{figure}[ht]
jerojasro@336	253 \interaction{hook.simple.init}
jerojasro@336	254 \caption{A simple hook that runs when a changeset is committed}
jerojasro@336	255 \label{ex:hook:init}
jerojasro@336	256 \end{figure}
jerojasro@336	257
jerojasro@336	258 All hooks follow the pattern in example~\ref{ex:hook:init}. You add
jerojasro@336	259 an entry to the \rcsection{hooks} section of your \hgrc. On the left
jerojasro@336	260 is the name of the event to trigger on; on the right is the action to
jerojasro@336	261 take. As you can see, you can run an arbitrary shell command in a
jerojasro@336	262 hook. Mercurial passes extra information to the hook using
jerojasro@336	263 environment variables (look for \envar{HG\_NODE} in the example).
jerojasro@336	264
jerojasro@336	265 \subsection{Performing multiple actions per event}
jerojasro@336	266
jerojasro@336	267 Quite often, you will want to define more than one hook for a
jerojasro@336	268 particular kind of event, as shown in example~\ref{ex:hook:ext}.
jerojasro@336	269 Mercurial lets you do this by adding an \emph{extension} to the end of
jerojasro@336	270 a hook's name. You extend a hook's name by giving the name of the
jerojasro@336	271 hook, followed by a full stop (the ``\texttt{.}'' character), followed
jerojasro@336	272 by some more text of your choosing. For example, Mercurial will run
jerojasro@336	273 both \texttt{commit.foo} and \texttt{commit.bar} when the
jerojasro@336	274 \texttt{commit} event occurs.
jerojasro@336	275
jerojasro@336	276 \begin{figure}[ht]
jerojasro@336	277 \interaction{hook.simple.ext}
jerojasro@336	278 \caption{Defining a second \hook{commit} hook}
jerojasro@336	279 \label{ex:hook:ext}
jerojasro@336	280 \end{figure}
jerojasro@336	281
jerojasro@336	282 To give a well-defined order of execution when there are multiple
jerojasro@336	283 hooks defined for an event, Mercurial sorts hooks by extension, and
jerojasro@336	284 executes the hook commands in this sorted order. In the above
jerojasro@336	285 example, it will execute \texttt{commit.bar} before
jerojasro@336	286 \texttt{commit.foo}, and \texttt{commit} before both.
jerojasro@336	287
jerojasro@336	288 It is a good idea to use a somewhat descriptive extension when you
jerojasro@336	289 define a new hook. This will help you to remember what the hook was
jerojasro@336	290 for. If the hook fails, you'll get an error message that contains the
jerojasro@336	291 hook name and extension, so using a descriptive extension could give
jerojasro@336	292 you an immediate hint as to why the hook failed (see
jerojasro@336	293 section~\ref{sec:hook:perm} for an example).
jerojasro@336	294
jerojasro@336	295 \subsection{Controlling whether an activity can proceed}
jerojasro@336	296 \label{sec:hook:perm}
jerojasro@336	297
jerojasro@336	298 In our earlier examples, we used the \hook{commit} hook, which is
jerojasro@336	299 run after a commit has completed. This is one of several Mercurial
jerojasro@336	300 hooks that run after an activity finishes. Such hooks have no way of
jerojasro@336	301 influencing the activity itself.
jerojasro@336	302
jerojasro@336	303 Mercurial defines a number of events that occur before an activity
jerojasro@336	304 starts; or after it starts, but before it finishes. Hooks that
jerojasro@336	305 trigger on these events have the added ability to choose whether the
jerojasro@336	306 activity can continue, or will abort.
jerojasro@336	307
jerojasro@336	308 The \hook{pretxncommit} hook runs after a commit has all but
jerojasro@336	309 completed. In other words, the metadata representing the changeset
jerojasro@336	310 has been written out to disk, but the transaction has not yet been
jerojasro@336	311 allowed to complete. The \hook{pretxncommit} hook has the ability to
jerojasro@336	312 decide whether the transaction can complete, or must be rolled back.
jerojasro@336	313
jerojasro@336	314 If the \hook{pretxncommit} hook exits with a status code of zero, the
jerojasro@336	315 transaction is allowed to complete; the commit finishes; and the
jerojasro@336	316 \hook{commit} hook is run. If the \hook{pretxncommit} hook exits with
jerojasro@336	317 a non-zero status code, the transaction is rolled back; the metadata
jerojasro@336	318 representing the changeset is erased; and the \hook{commit} hook is
jerojasro@336	319 not run.
jerojasro@336	320
jerojasro@336	321 \begin{figure}[ht]
jerojasro@336	322 \interaction{hook.simple.pretxncommit}
jerojasro@336	323 \caption{Using the \hook{pretxncommit} hook to control commits}
jerojasro@336	324 \label{ex:hook:pretxncommit}
jerojasro@336	325 \end{figure}
jerojasro@336	326
jerojasro@336	327 The hook in example~\ref{ex:hook:pretxncommit} checks that a commit
jerojasro@336	328 comment contains a bug ID. If it does, the commit can complete. If
jerojasro@336	329 not, the commit is rolled back.
jerojasro@336	330
jerojasro@336	331 \section{Writing your own hooks}
jerojasro@336	332
jerojasro@336	333 When you are writing a hook, you might find it useful to run Mercurial
jerojasro@336	334 either with the \hggopt{-v} option, or the \rcitem{ui}{verbose} config
jerojasro@336	335 item set to ``true''. When you do so, Mercurial will print a message
jerojasro@336	336 before it calls each hook.
jerojasro@336	337
jerojasro@336	338 \subsection{Choosing how your hook should run}
jerojasro@336	339 \label{sec:hook:lang}
jerojasro@336	340
jerojasro@336	341 You can write a hook either as a normal program---typically a shell
jerojasro@336	342 script---or as a Python function that is executed within the Mercurial
jerojasro@336	343 process.
jerojasro@336	344
jerojasro@336	345 Writing a hook as an external program has the advantage that it
jerojasro@336	346 requires no knowledge of Mercurial's internals. You can call normal
jerojasro@336	347 Mercurial commands to get any added information you need. The
jerojasro@336	348 trade-off is that external hooks are slower than in-process hooks.
jerojasro@336	349
jerojasro@336	350 An in-process Python hook has complete access to the Mercurial API,
jerojasro@336	351 and does not ``shell out'' to another process, so it is inherently
jerojasro@336	352 faster than an external hook. It is also easier to obtain much of the
jerojasro@336	353 information that a hook requires by using the Mercurial API than by
jerojasro@336	354 running Mercurial commands.
jerojasro@336	355
jerojasro@336	356 If you are comfortable with Python, or require high performance,
jerojasro@336	357 writing your hooks in Python may be a good choice. However, when you
jerojasro@336	358 have a straightforward hook to write and you don't need to care about
jerojasro@336	359 performance (probably the majority of hooks), a shell script is
jerojasro@336	360 perfectly fine.
jerojasro@336	361
jerojasro@336	362 \subsection{Hook parameters}
jerojasro@336	363 \label{sec:hook:param}
jerojasro@336	364
jerojasro@336	365 Mercurial calls each hook with a set of well-defined parameters. In
jerojasro@336	366 Python, a parameter is passed as a keyword argument to your hook
jerojasro@336	367 function. For an external program, a parameter is passed as an
jerojasro@336	368 environment variable.
jerojasro@336	369
jerojasro@336	370 Whether your hook is written in Python or as a shell script, the
jerojasro@336	371 hook-specific parameter names and values will be the same. A boolean
jerojasro@336	372 parameter will be represented as a boolean value in Python, but as the
jerojasro@336	373 number 1 (for ``true'') or 0 (for ``false'') as an environment
jerojasro@336	374 variable for an external hook. If a hook parameter is named
jerojasro@336	375 \texttt{foo}, the keyword argument for a Python hook will also be
jerojasro@336	376 named \texttt{foo}, while the environment variable for an external
jerojasro@336	377 hook will be named \texttt{HG\_FOO}.
jerojasro@336	378
jerojasro@336	379 \subsection{Hook return values and activity control}
jerojasro@336	380
jerojasro@336	381 A hook that executes successfully must exit with a status of zero if
jerojasro@336	382 external, or return boolean ``false'' if in-process. Failure is
jerojasro@336	383 indicated with a non-zero exit status from an external hook, or an
jerojasro@336	384 in-process hook returning boolean ``true''. If an in-process hook
jerojasro@336	385 raises an exception, the hook is considered to have failed.
jerojasro@336	386
jerojasro@336	387 For a hook that controls whether an activity can proceed, zero/false
jerojasro@336	388 means ``allow'', while non-zero/true/exception means ``deny''.
jerojasro@336	389
jerojasro@336	390 \subsection{Writing an external hook}
jerojasro@336	391
jerojasro@336	392 When you define an external hook in your \hgrc\ and the hook is run,
jerojasro@336	393 its value is passed to your shell, which interprets it. This means
jerojasro@336	394 that you can use normal shell constructs in the body of the hook.
jerojasro@336	395
jerojasro@336	396 An executable hook is always run with its current directory set to a
jerojasro@336	397 repository's root directory.
jerojasro@336	398
jerojasro@336	399 Each hook parameter is passed in as an environment variable; the name
jerojasro@336	400 is upper-cased, and prefixed with the string ``\texttt{HG\_}''.
jerojasro@336	401
jerojasro@336	402 With the exception of hook parameters, Mercurial does not set or
jerojasro@336	403 modify any environment variables when running a hook. This is useful
jerojasro@336	404 to remember if you are writing a site-wide hook that may be run by a
jerojasro@336	405 number of different users with differing environment variables set.
jerojasro@336	406 In multi-user situations, you should not rely on environment variables
jerojasro@336	407 being set to the values you have in your environment when testing the
jerojasro@336	408 hook.
jerojasro@336	409
jerojasro@336	410 \subsection{Telling Mercurial to use an in-process hook}
jerojasro@336	411
jerojasro@336	412 The \hgrc\ syntax for defining an in-process hook is slightly
jerojasro@336	413 different than for an executable hook. The value of the hook must
jerojasro@336	414 start with the text ``\texttt{python:}'', and continue with the
jerojasro@336	415 fully-qualified name of a callable object to use as the hook's value.
jerojasro@336	416
jerojasro@336	417 The module in which a hook lives is automatically imported when a hook
jerojasro@336	418 is run. So long as you have the module name and \envar{PYTHONPATH}
jerojasro@336	419 right, it should ``just work''.
jerojasro@336	420
jerojasro@336	421 The following \hgrc\ example snippet illustrates the syntax and
jerojasro@336	422 meaning of the notions we just described.
jerojasro@336	423 \begin{codesample2}
jerojasro@336	424 [hooks]
jerojasro@336	425 commit.example = python:mymodule.submodule.myhook
jerojasro@336	426 \end{codesample2}
jerojasro@336	427 When Mercurial runs the \texttt{commit.example} hook, it imports
jerojasro@336	428 \texttt{mymodule.submodule}, looks for the callable object named
jerojasro@336	429 \texttt{myhook}, and calls it.
jerojasro@336	430
jerojasro@336	431 \subsection{Writing an in-process hook}
jerojasro@336	432
jerojasro@336	433 The simplest in-process hook does nothing, but illustrates the basic
jerojasro@336	434 shape of the hook API:
jerojasro@336	435 \begin{codesample2}
jerojasro@336	436 def myhook(ui, repo, **kwargs):
jerojasro@336	437 pass
jerojasro@336	438 \end{codesample2}
jerojasro@336	439 The first argument to a Python hook is always a
jerojasro@336	440 \pymodclass{mercurial.ui}{ui} object. The second is a repository object;
jerojasro@336	441 at the moment, it is always an instance of
jerojasro@336	442 \pymodclass{mercurial.localrepo}{localrepository}. Following these two
jerojasro@336	443 arguments are other keyword arguments. Which ones are passed in
jerojasro@336	444 depends on the hook being called, but a hook can ignore arguments it
jerojasro@336	445 doesn't care about by dropping them into a keyword argument dict, as
jerojasro@336	446 with \texttt{**kwargs} above.
jerojasro@336	447
jerojasro@336	448 \section{Some hook examples}
jerojasro@336	449
jerojasro@336	450 \subsection{Writing meaningful commit messages}
jerojasro@336	451
jerojasro@336	452 It's hard to imagine a useful commit message being very short. The
jerojasro@336	453 simple \hook{pretxncommit} hook of figure~\ref{ex:hook:msglen.go}
jerojasro@336	454 will prevent you from committing a changeset with a message that is
jerojasro@336	455 less than ten bytes long.
jerojasro@336	456
jerojasro@336	457 \begin{figure}[ht]
jerojasro@336	458 \interaction{hook.msglen.go}
jerojasro@336	459 \caption{A hook that forbids overly short commit messages}
jerojasro@336	460 \label{ex:hook:msglen.go}
jerojasro@336	461 \end{figure}
jerojasro@336	462
jerojasro@336	463 \subsection{Checking for trailing whitespace}
jerojasro@336	464
jerojasro@336	465 An interesting use of a commit-related hook is to help you to write
jerojasro@336	466 cleaner code. A simple example of ``cleaner code'' is the dictum that
jerojasro@336	467 a change should not add any new lines of text that contain ``trailing
jerojasro@336	468 whitespace''. Trailing whitespace is a series of space and tab
jerojasro@336	469 characters at the end of a line of text. In most cases, trailing
jerojasro@336	470 whitespace is unnecessary, invisible noise, but it is occasionally
jerojasro@336	471 problematic, and people often prefer to get rid of it.
jerojasro@336	472
jerojasro@336	473 You can use either the \hook{precommit} or \hook{pretxncommit} hook to
jerojasro@336	474 tell whether you have a trailing whitespace problem. If you use the
jerojasro@336	475 \hook{precommit} hook, the hook will not know which files you are
jerojasro@336	476 committing, so it will have to check every modified file in the
jerojasro@336	477 repository for trailing white space. If you want to commit a change
jerojasro@336	478 to just the file \filename{foo}, but the file \filename{bar} contains
jerojasro@336	479 trailing whitespace, doing a check in the \hook{precommit} hook will
jerojasro@336	480 prevent you from committing \filename{foo} due to the problem with
jerojasro@336	481 \filename{bar}. This doesn't seem right.
jerojasro@336	482
jerojasro@336	483 Should you choose the \hook{pretxncommit} hook, the check won't occur
jerojasro@336	484 until just before the transaction for the commit completes. This will
jerojasro@336	485 allow you to check for problems only the exact files that are being
jerojasro@336	486 committed. However, if you entered the commit message interactively
jerojasro@336	487 and the hook fails, the transaction will roll back; you'll have to
jerojasro@336	488 re-enter the commit message after you fix the trailing whitespace and
jerojasro@336	489 run \hgcmd{commit} again.
jerojasro@336	490
jerojasro@336	491 \begin{figure}[ht]
jerojasro@336	492 \interaction{hook.ws.simple}
jerojasro@336	493 \caption{A simple hook that checks for trailing whitespace}
jerojasro@336	494 \label{ex:hook:ws.simple}
jerojasro@336	495 \end{figure}
jerojasro@336	496
jerojasro@336	497 Figure~\ref{ex:hook:ws.simple} introduces a simple \hook{pretxncommit}
jerojasro@336	498 hook that checks for trailing whitespace. This hook is short, but not
jerojasro@336	499 very helpful. It exits with an error status if a change adds a line
jerojasro@336	500 with trailing whitespace to any file, but does not print any
jerojasro@336	501 information that might help us to identify the offending file or
jerojasro@336	502 line. It also has the nice property of not paying attention to
jerojasro@336	503 unmodified lines; only lines that introduce new trailing whitespace
jerojasro@336	504 cause problems.
jerojasro@336	505
jerojasro@336	506 \begin{figure}[ht]
jerojasro@336	507 \interaction{hook.ws.better}
jerojasro@336	508 \caption{A better trailing whitespace hook}
jerojasro@336	509 \label{ex:hook:ws.better}
jerojasro@336	510 \end{figure}
jerojasro@336	511
jerojasro@336	512 The example of figure~\ref{ex:hook:ws.better} is much more complex,
jerojasro@336	513 but also more useful. It parses a unified diff to see if any lines
jerojasro@336	514 add trailing whitespace, and prints the name of the file and the line
jerojasro@336	515 number of each such occurrence. Even better, if the change adds
jerojasro@336	516 trailing whitespace, this hook saves the commit comment and prints the
jerojasro@336	517 name of the save file before exiting and telling Mercurial to roll the
jerojasro@336	518 transaction back, so you can use
jerojasro@336	519 \hgcmdargs{commit}{\hgopt{commit}{-l}~\emph{filename}} to reuse the
jerojasro@336	520 saved commit message once you've corrected the problem.
jerojasro@336	521
jerojasro@336	522 As a final aside, note in figure~\ref{ex:hook:ws.better} the use of
jerojasro@336	523 \command{perl}'s in-place editing feature to get rid of trailing
jerojasro@336	524 whitespace from a file. This is concise and useful enough that I will
jerojasro@336	525 reproduce it here.
jerojasro@336	526 \begin{codesample2}
jerojasro@336	527 perl -pi -e 's,\\s+\$,,' filename
jerojasro@336	528 \end{codesample2}
jerojasro@336	529
jerojasro@336	530 \section{Bundled hooks}
jerojasro@336	531
jerojasro@336	532 Mercurial ships with several bundled hooks. You can find them in the
jerojasro@336	533 \dirname{hgext} directory of a Mercurial source tree. If you are
jerojasro@336	534 using a Mercurial binary package, the hooks will be located in the
jerojasro@336	535 \dirname{hgext} directory of wherever your package installer put
jerojasro@336	536 Mercurial.
jerojasro@336	537
jerojasro@336	538 \subsection{\hgext{acl}---access control for parts of a repository}
jerojasro@336	539
jerojasro@336	540 The \hgext{acl} extension lets you control which remote users are
jerojasro@336	541 allowed to push changesets to a networked server. You can protect any
jerojasro@336	542 portion of a repository (including the entire repo), so that a
jerojasro@336	543 specific remote user can push changes that do not affect the protected
jerojasro@336	544 portion.
jerojasro@336	545
jerojasro@336	546 This extension implements access control based on the identity of the
jerojasro@336	547 user performing a push, \emph{not} on who committed the changesets
jerojasro@336	548 they're pushing. It makes sense to use this hook only if you have a
jerojasro@336	549 locked-down server environment that authenticates remote users, and
jerojasro@336	550 you want to be sure that only specific users are allowed to push
jerojasro@336	551 changes to that server.
jerojasro@336	552
jerojasro@336	553 \subsubsection{Configuring the \hook{acl} hook}
jerojasro@336	554
jerojasro@336	555 In order to manage incoming changesets, the \hgext{acl} hook must be
jerojasro@336	556 used as a \hook{pretxnchangegroup} hook. This lets it see which files
jerojasro@336	557 are modified by each incoming changeset, and roll back a group of
jerojasro@336	558 changesets if they modify ``forbidden'' files. Example:
jerojasro@336	559 \begin{codesample2}
jerojasro@336	560 [hooks]
jerojasro@336	561 pretxnchangegroup.acl = python:hgext.acl.hook
jerojasro@336	562 \end{codesample2}
jerojasro@336	563
jerojasro@336	564 The \hgext{acl} extension is configured using three sections.
jerojasro@336	565
jerojasro@336	566 The \rcsection{acl} section has only one entry, \rcitem{acl}{sources},
jerojasro@336	567 which lists the sources of incoming changesets that the hook should
jerojasro@336	568 pay attention to. You don't normally need to configure this section.
jerojasro@336	569 \begin{itemize}
jerojasro@336	570 \item[\rcitem{acl}{serve}] Control incoming changesets that are arriving
jerojasro@336	571 from a remote repository over http or ssh. This is the default
jerojasro@336	572 value of \rcitem{acl}{sources}, and usually the only setting you'll
jerojasro@336	573 need for this configuration item.
jerojasro@336	574 \item[\rcitem{acl}{pull}] Control incoming changesets that are
jerojasro@336	575 arriving via a pull from a local repository.
jerojasro@336	576 \item[\rcitem{acl}{push}] Control incoming changesets that are
jerojasro@336	577 arriving via a push from a local repository.
jerojasro@336	578 \item[\rcitem{acl}{bundle}] Control incoming changesets that are
jerojasro@336	579 arriving from another repository via a bundle.
jerojasro@336	580 \end{itemize}
jerojasro@336	581
jerojasro@336	582 The \rcsection{acl.allow} section controls the users that are allowed to
jerojasro@336	583 add changesets to the repository. If this section is not present, all
jerojasro@336	584 users that are not explicitly denied are allowed. If this section is
jerojasro@336	585 present, all users that are not explicitly allowed are denied (so an
jerojasro@336	586 empty section means that all users are denied).
jerojasro@336	587
jerojasro@336	588 The \rcsection{acl.deny} section determines which users are denied
jerojasro@336	589 from adding changesets to the repository. If this section is not
jerojasro@336	590 present or is empty, no users are denied.
jerojasro@336	591
jerojasro@336	592 The syntaxes for the \rcsection{acl.allow} and \rcsection{acl.deny}
jerojasro@336	593 sections are identical. On the left of each entry is a glob pattern
jerojasro@336	594 that matches files or directories, relative to the root of the
jerojasro@336	595 repository; on the right, a user name.
jerojasro@336	596
jerojasro@336	597 In the following example, the user \texttt{docwriter} can only push
jerojasro@336	598 changes to the \dirname{docs} subtree of the repository, while
jerojasro@336	599 \texttt{intern} can push changes to any file or directory except
jerojasro@336	600 \dirname{source/sensitive}.
jerojasro@336	601 \begin{codesample2}
jerojasro@336	602 [acl.allow]
jerojasro@336	603 docs/** = docwriter
jerojasro@336	604
jerojasro@336	605 [acl.deny]
jerojasro@336	606 source/sensitive/** = intern
jerojasro@336	607 \end{codesample2}
jerojasro@336	608
jerojasro@336	609 \subsubsection{Testing and troubleshooting}
jerojasro@336	610
jerojasro@336	611 If you want to test the \hgext{acl} hook, run it with Mercurial's
jerojasro@336	612 debugging output enabled. Since you'll probably be running it on a
jerojasro@336	613 server where it's not convenient (or sometimes possible) to pass in
jerojasro@336	614 the \hggopt{--debug} option, don't forget that you can enable
jerojasro@336	615 debugging output in your \hgrc:
jerojasro@336	616 \begin{codesample2}
jerojasro@336	617 [ui]
jerojasro@336	618 debug = true
jerojasro@336	619 \end{codesample2}
jerojasro@336	620 With this enabled, the \hgext{acl} hook will print enough information
jerojasro@336	621 to let you figure out why it is allowing or forbidding pushes from
jerojasro@336	622 specific users.
jerojasro@336	623
jerojasro@336	624 \subsection{\hgext{bugzilla}---integration with Bugzilla}
jerojasro@336	625
jerojasro@336	626 The \hgext{bugzilla} extension adds a comment to a Bugzilla bug
jerojasro@336	627 whenever it finds a reference to that bug ID in a commit comment. You
jerojasro@336	628 can install this hook on a shared server, so that any time a remote
jerojasro@336	629 user pushes changes to this server, the hook gets run.
jerojasro@336	630
jerojasro@336	631 It adds a comment to the bug that looks like this (you can configure
jerojasro@336	632 the contents of the comment---see below):
jerojasro@336	633 \begin{codesample2}
jerojasro@336	634 Changeset aad8b264143a, made by Joe User <joe.user@domain.com> in
jerojasro@336	635 the frobnitz repository, refers to this bug.
jerojasro@336	636
jerojasro@336	637 For complete details, see
jerojasro@336	638 http://hg.domain.com/frobnitz?cmd=changeset;node=aad8b264143a
jerojasro@336	639
jerojasro@336	640 Changeset description:
jerojasro@336	641 Fix bug 10483 by guarding against some NULL pointers
jerojasro@336	642 \end{codesample2}
jerojasro@336	643 The value of this hook is that it automates the process of updating a
jerojasro@336	644 bug any time a changeset refers to it. If you configure the hook
jerojasro@336	645 properly, it makes it easy for people to browse straight from a
jerojasro@336	646 Bugzilla bug to a changeset that refers to that bug.
jerojasro@336	647
jerojasro@336	648 You can use the code in this hook as a starting point for some more
jerojasro@336	649 exotic Bugzilla integration recipes. Here are a few possibilities:
jerojasro@336	650 \begin{itemize}
jerojasro@336	651 \item Require that every changeset pushed to the server have a valid
jerojasro@336	652 bug~ID in its commit comment. In this case, you'd want to configure
jerojasro@336	653 the hook as a \hook{pretxncommit} hook. This would allow the hook
jerojasro@336	654 to reject changes that didn't contain bug IDs.
jerojasro@336	655 \item Allow incoming changesets to automatically modify the
jerojasro@336	656 \emph{state} of a bug, as well as simply adding a comment. For
jerojasro@336	657 example, the hook could recognise the string ``fixed bug 31337'' as
jerojasro@336	658 indicating that it should update the state of bug 31337 to
jerojasro@336	659 ``requires testing''.
jerojasro@336	660 \end{itemize}
jerojasro@336	661
jerojasro@336	662 \subsubsection{Configuring the \hook{bugzilla} hook}
jerojasro@336	663 \label{sec:hook:bugzilla:config}
jerojasro@336	664
jerojasro@336	665 You should configure this hook in your server's \hgrc\ as an
jerojasro@336	666 \hook{incoming} hook, for example as follows:
jerojasro@336	667 \begin{codesample2}
jerojasro@336	668 [hooks]
jerojasro@336	669 incoming.bugzilla = python:hgext.bugzilla.hook
jerojasro@336	670 \end{codesample2}
jerojasro@336	671
jerojasro@336	672 Because of the specialised nature of this hook, and because Bugzilla
jerojasro@336	673 was not written with this kind of integration in mind, configuring
jerojasro@336	674 this hook is a somewhat involved process.
jerojasro@336	675
jerojasro@336	676 Before you begin, you must install the MySQL bindings for Python on
jerojasro@336	677 the host(s) where you'll be running the hook. If this is not
jerojasro@336	678 available as a binary package for your system, you can download it
jerojasro@336	679 from~\cite{web:mysql-python}.
jerojasro@336	680
jerojasro@336	681 Configuration information for this hook lives in the
jerojasro@336	682 \rcsection{bugzilla} section of your \hgrc.
jerojasro@336	683 \begin{itemize}
jerojasro@336	684 \item[\rcitem{bugzilla}{version}] The version of Bugzilla installed on
jerojasro@336	685 the server. The database schema that Bugzilla uses changes
jerojasro@336	686 occasionally, so this hook has to know exactly which schema to use.
jerojasro@336	687 At the moment, the only version supported is \texttt{2.16}.
jerojasro@336	688 \item[\rcitem{bugzilla}{host}] The hostname of the MySQL server that
jerojasro@336	689 stores your Bugzilla data. The database must be configured to allow
jerojasro@336	690 connections from whatever host you are running the \hook{bugzilla}
jerojasro@336	691 hook on.
jerojasro@336	692 \item[\rcitem{bugzilla}{user}] The username with which to connect to
jerojasro@336	693 the MySQL server. The database must be configured to allow this
jerojasro@336	694 user to connect from whatever host you are running the
jerojasro@336	695 \hook{bugzilla} hook on. This user must be able to access and
jerojasro@336	696 modify Bugzilla tables. The default value of this item is
jerojasro@336	697 \texttt{bugs}, which is the standard name of the Bugzilla user in a
jerojasro@336	698 MySQL database.
jerojasro@336	699 \item[\rcitem{bugzilla}{password}] The MySQL password for the user you
jerojasro@336	700 configured above. This is stored as plain text, so you should make
jerojasro@336	701 sure that unauthorised users cannot read the \hgrc\ file where you
jerojasro@336	702 store this information.
jerojasro@336	703 \item[\rcitem{bugzilla}{db}] The name of the Bugzilla database on the
jerojasro@336	704 MySQL server. The default value of this item is \texttt{bugs},
jerojasro@336	705 which is the standard name of the MySQL database where Bugzilla
jerojasro@336	706 stores its data.
jerojasro@336	707 \item[\rcitem{bugzilla}{notify}] If you want Bugzilla to send out a
jerojasro@336	708 notification email to subscribers after this hook has added a
jerojasro@336	709 comment to a bug, you will need this hook to run a command whenever
jerojasro@336	710 it updates the database. The command to run depends on where you
jerojasro@336	711 have installed Bugzilla, but it will typically look something like
jerojasro@336	712 this, if you have Bugzilla installed in
jerojasro@336	713 \dirname{/var/www/html/bugzilla}:
jerojasro@336	714 \begin{codesample4}
jerojasro@336	715 cd /var/www/html/bugzilla && ./processmail %s nobody@nowhere.com
jerojasro@336	716 \end{codesample4}
jerojasro@336	717 The Bugzilla \texttt{processmail} program expects to be given a
jerojasro@336	718 bug~ID (the hook replaces ``\texttt{\%s}'' with the bug~ID) and an
jerojasro@336	719 email address. It also expects to be able to write to some files in
jerojasro@336	720 the directory that it runs in. If Bugzilla and this hook are not
jerojasro@336	721 installed on the same machine, you will need to find a way to run
jerojasro@336	722 \texttt{processmail} on the server where Bugzilla is installed.
jerojasro@336	723 \end{itemize}
jerojasro@336	724
jerojasro@336	725 \subsubsection{Mapping committer names to Bugzilla user names}
jerojasro@336	726
jerojasro@336	727 By default, the \hgext{bugzilla} hook tries to use the email address
jerojasro@336	728 of a changeset's committer as the Bugzilla user name with which to
jerojasro@336	729 update a bug. If this does not suit your needs, you can map committer
jerojasro@336	730 email addresses to Bugzilla user names using a \rcsection{usermap}
jerojasro@336	731 section.
jerojasro@336	732
jerojasro@336	733 Each item in the \rcsection{usermap} section contains an email address
jerojasro@336	734 on the left, and a Bugzilla user name on the right.
jerojasro@336	735 \begin{codesample2}
jerojasro@336	736 [usermap]
jerojasro@336	737 jane.user@example.com = jane
jerojasro@336	738 \end{codesample2}
jerojasro@336	739 You can either keep the \rcsection{usermap} data in a normal \hgrc, or
jerojasro@336	740 tell the \hgext{bugzilla} hook to read the information from an
jerojasro@336	741 external \filename{usermap} file. In the latter case, you can store
jerojasro@336	742 \filename{usermap} data by itself in (for example) a user-modifiable
jerojasro@336	743 repository. This makes it possible to let your users maintain their
jerojasro@336	744 own \rcitem{bugzilla}{usermap} entries. The main \hgrc\ file might
jerojasro@336	745 look like this:
jerojasro@336	746 \begin{codesample2}
jerojasro@336	747 # regular hgrc file refers to external usermap file
jerojasro@336	748 [bugzilla]
jerojasro@336	749 usermap = /home/hg/repos/userdata/bugzilla-usermap.conf
jerojasro@336	750 \end{codesample2}
jerojasro@336	751 While the \filename{usermap} file that it refers to might look like
jerojasro@336	752 this:
jerojasro@336	753 \begin{codesample2}
jerojasro@336	754 # bugzilla-usermap.conf - inside a hg repository
jerojasro@336	755 [usermap]
jerojasro@336	756 stephanie@example.com = steph
jerojasro@336	757 \end{codesample2}
jerojasro@336	758
jerojasro@336	759 \subsubsection{Configuring the text that gets added to a bug}
jerojasro@336	760
jerojasro@336	761 You can configure the text that this hook adds as a comment; you
jerojasro@336	762 specify it in the form of a Mercurial template. Several \hgrc\
jerojasro@336	763 entries (still in the \rcsection{bugzilla} section) control this
jerojasro@336	764 behaviour.
jerojasro@336	765 \begin{itemize}
jerojasro@336	766 \item[\texttt{strip}] The number of leading path elements to strip
jerojasro@336	767 from a repository's path name to construct a partial path for a URL.
jerojasro@336	768 For example, if the repositories on your server live under
jerojasro@336	769 \dirname{/home/hg/repos}, and you have a repository whose path is
jerojasro@336	770 \dirname{/home/hg/repos/app/tests}, then setting \texttt{strip} to
jerojasro@336	771 \texttt{4} will give a partial path of \dirname{app/tests}. The
jerojasro@336	772 hook will make this partial path available when expanding a
jerojasro@336	773 template, as \texttt{webroot}.
jerojasro@336	774 \item[\texttt{template}] The text of the template to use. In addition
jerojasro@336	775 to the usual changeset-related variables, this template can use
jerojasro@336	776 \texttt{hgweb} (the value of the \texttt{hgweb} configuration item
jerojasro@336	777 above) and \texttt{webroot} (the path constructed using
jerojasro@336	778 \texttt{strip} above).
jerojasro@336	779 \end{itemize}
jerojasro@336	780
jerojasro@336	781 In addition, you can add a \rcitem{web}{baseurl} item to the
jerojasro@336	782 \rcsection{web} section of your \hgrc. The \hgext{bugzilla} hook will
jerojasro@336	783 make this available when expanding a template, as the base string to
jerojasro@336	784 use when constructing a URL that will let users browse from a Bugzilla
jerojasro@336	785 comment to view a changeset. Example:
jerojasro@336	786 \begin{codesample2}
jerojasro@336	787 [web]
jerojasro@336	788 baseurl = http://hg.domain.com/
jerojasro@336	789 \end{codesample2}
jerojasro@336	790
jerojasro@336	791 Here is an example set of \hgext{bugzilla} hook config information.
jerojasro@336	792 \begin{codesample2}
jerojasro@336	793 [bugzilla]
jerojasro@336	794 host = bugzilla.example.com
jerojasro@336	795 password = mypassword
jerojasro@336	796 version = 2.16
jerojasro@336	797 # server-side repos live in /home/hg/repos, so strip 4 leading
jerojasro@336	798 # separators
jerojasro@336	799 strip = 4
jerojasro@336	800 hgweb = http://hg.example.com/
jerojasro@336	801 usermap = /home/hg/repos/notify/bugzilla.conf
jerojasro@336	802 template = Changeset \{node\|short\}, made by \{author\} in the \{webroot\}
jerojasro@336	803 repo, refers to this bug.\\nFor complete details, see
jerojasro@336	804 \{hgweb\}\{webroot\}?cmd=changeset;node=\{node\|short\}\\nChangeset
jerojasro@336	805 description:\\n\\t\{desc\|tabindent\}
jerojasro@336	806 \end{codesample2}
jerojasro@336	807
jerojasro@336	808 \subsubsection{Testing and troubleshooting}
jerojasro@336	809
jerojasro@336	810 The most common problems with configuring the \hgext{bugzilla} hook
jerojasro@336	811 relate to running Bugzilla's \filename{processmail} script and mapping
jerojasro@336	812 committer names to user names.
jerojasro@336	813
jerojasro@336	814 Recall from section~\ref{sec:hook:bugzilla:config} above that the user
jerojasro@336	815 that runs the Mercurial process on the server is also the one that
jerojasro@336	816 will run the \filename{processmail} script. The
jerojasro@336	817 \filename{processmail} script sometimes causes Bugzilla to write to
jerojasro@336	818 files in its configuration directory, and Bugzilla's configuration
jerojasro@336	819 files are usually owned by the user that your web server runs under.
jerojasro@336	820
jerojasro@336	821 You can cause \filename{processmail} to be run with the suitable
jerojasro@336	822 user's identity using the \command{sudo} command. Here is an example
jerojasro@336	823 entry for a \filename{sudoers} file.
jerojasro@336	824 \begin{codesample2}
jerojasro@336	825 hg_user = (httpd_user) NOPASSWD: /var/www/html/bugzilla/processmail-wrapper %s
jerojasro@336	826 \end{codesample2}
jerojasro@336	827 This allows the \texttt{hg\_user} user to run a
jerojasro@336	828 \filename{processmail-wrapper} program under the identity of
jerojasro@336	829 \texttt{httpd\_user}.
jerojasro@336	830
jerojasro@336	831 This indirection through a wrapper script is necessary, because
jerojasro@336	832 \filename{processmail} expects to be run with its current directory
jerojasro@336	833 set to wherever you installed Bugzilla; you can't specify that kind of
jerojasro@336	834 constraint in a \filename{sudoers} file. The contents of the wrapper
jerojasro@336	835 script are simple:
jerojasro@336	836 \begin{codesample2}
jerojasro@336	837 #!/bin/sh
jerojasro@336	838 cd `dirname $0` && ./processmail "$1" nobody@example.com
jerojasro@336	839 \end{codesample2}
jerojasro@336	840 It doesn't seem to matter what email address you pass to
jerojasro@336	841 \filename{processmail}.
jerojasro@336	842
jerojasro@336	843 If your \rcsection{usermap} is not set up correctly, users will see an
jerojasro@336	844 error message from the \hgext{bugzilla} hook when they push changes
jerojasro@336	845 to the server. The error message will look like this:
jerojasro@336	846 \begin{codesample2}
jerojasro@336	847 cannot find bugzilla user id for john.q.public@example.com
jerojasro@336	848 \end{codesample2}
jerojasro@336	849 What this means is that the committer's address,
jerojasro@336	850 \texttt{john.q.public@example.com}, is not a valid Bugzilla user name,
jerojasro@336	851 nor does it have an entry in your \rcsection{usermap} that maps it to
jerojasro@336	852 a valid Bugzilla user name.
jerojasro@336	853
jerojasro@336	854 \subsection{\hgext{notify}---send email notifications}
jerojasro@336	855
jerojasro@336	856 Although Mercurial's built-in web server provides RSS feeds of changes
jerojasro@336	857 in every repository, many people prefer to receive change
jerojasro@336	858 notifications via email. The \hgext{notify} hook lets you send out
jerojasro@336	859 notifications to a set of email addresses whenever changesets arrive
jerojasro@336	860 that those subscribers are interested in.
jerojasro@336	861
jerojasro@336	862 As with the \hgext{bugzilla} hook, the \hgext{notify} hook is
jerojasro@336	863 template-driven, so you can customise the contents of the notification
jerojasro@336	864 messages that it sends.
jerojasro@336	865
jerojasro@336	866 By default, the \hgext{notify} hook includes a diff of every changeset
jerojasro@336	867 that it sends out; you can limit the size of the diff, or turn this
jerojasro@336	868 feature off entirely. It is useful for letting subscribers review
jerojasro@336	869 changes immediately, rather than clicking to follow a URL.
jerojasro@336	870
jerojasro@336	871 \subsubsection{Configuring the \hgext{notify} hook}
jerojasro@336	872
jerojasro@336	873 You can set up the \hgext{notify} hook to send one email message per
jerojasro@336	874 incoming changeset, or one per incoming group of changesets (all those
jerojasro@336	875 that arrived in a single pull or push).
jerojasro@336	876 \begin{codesample2}
jerojasro@336	877 [hooks]
jerojasro@336	878 # send one email per group of changes
jerojasro@336	879 changegroup.notify = python:hgext.notify.hook
jerojasro@336	880 # send one email per change
jerojasro@336	881 incoming.notify = python:hgext.notify.hook
jerojasro@336	882 \end{codesample2}
jerojasro@336	883
jerojasro@336	884 Configuration information for this hook lives in the
jerojasro@336	885 \rcsection{notify} section of a \hgrc\ file.
jerojasro@336	886 \begin{itemize}
jerojasro@336	887 \item[\rcitem{notify}{test}] By default, this hook does not send out
jerojasro@336	888 email at all; instead, it prints the message that it \emph{would}
jerojasro@336	889 send. Set this item to \texttt{false} to allow email to be sent.
jerojasro@336	890 The reason that sending of email is turned off by default is that it
jerojasro@336	891 takes several tries to configure this extension exactly as you would
jerojasro@336	892 like, and it would be bad form to spam subscribers with a number of
jerojasro@336	893 ``broken'' notifications while you debug your configuration.
jerojasro@336	894 \item[\rcitem{notify}{config}] The path to a configuration file that
jerojasro@336	895 contains subscription information. This is kept separate from the
jerojasro@336	896 main \hgrc\ so that you can maintain it in a repository of its own.
jerojasro@336	897 People can then clone that repository, update their subscriptions,
jerojasro@336	898 and push the changes back to your server.
jerojasro@336	899 \item[\rcitem{notify}{strip}] The number of leading path separator
jerojasro@336	900 characters to strip from a repository's path, when deciding whether
jerojasro@336	901 a repository has subscribers. For example, if the repositories on
jerojasro@336	902 your server live in \dirname{/home/hg/repos}, and \hgext{notify} is
jerojasro@336	903 considering a repository named \dirname{/home/hg/repos/shared/test},
jerojasro@336	904 setting \rcitem{notify}{strip} to \texttt{4} will cause
jerojasro@336	905 \hgext{notify} to trim the path it considers down to
jerojasro@336	906 \dirname{shared/test}, and it will match subscribers against that.
jerojasro@336	907 \item[\rcitem{notify}{template}] The template text to use when sending
jerojasro@336	908 messages. This specifies both the contents of the message header
jerojasro@336	909 and its body.
jerojasro@336	910 \item[\rcitem{notify}{maxdiff}] The maximum number of lines of diff
jerojasro@336	911 data to append to the end of a message. If a diff is longer than
jerojasro@336	912 this, it is truncated. By default, this is set to 300. Set this to
jerojasro@336	913 \texttt{0} to omit diffs from notification emails.
jerojasro@336	914 \item[\rcitem{notify}{sources}] A list of sources of changesets to
jerojasro@336	915 consider. This lets you limit \hgext{notify} to only sending out
jerojasro@336	916 email about changes that remote users pushed into this repository
jerojasro@336	917 via a server, for example. See section~\ref{sec:hook:sources} for
jerojasro@336	918 the sources you can specify here.
jerojasro@336	919 \end{itemize}
jerojasro@336	920
jerojasro@336	921 If you set the \rcitem{web}{baseurl} item in the \rcsection{web}
jerojasro@336	922 section, you can use it in a template; it will be available as
jerojasro@336	923 \texttt{webroot}.
jerojasro@336	924
jerojasro@336	925 Here is an example set of \hgext{notify} configuration information.
jerojasro@336	926 \begin{codesample2}
jerojasro@336	927 [notify]
jerojasro@336	928 # really send email
jerojasro@336	929 test = false
jerojasro@336	930 # subscriber data lives in the notify repo
jerojasro@336	931 config = /home/hg/repos/notify/notify.conf
jerojasro@336	932 # repos live in /home/hg/repos on server, so strip 4 "/" chars
jerojasro@336	933 strip = 4
jerojasro@336	934 template = X-Hg-Repo: \{webroot\}
jerojasro@336	935 Subject: \{webroot\}: \{desc\|firstline\|strip\}
jerojasro@336	936 From: \{author\}
jerojasro@336	937
jerojasro@336	938 changeset \{node\|short\} in \{root\}
jerojasro@336	939 details: \{baseurl\}\{webroot\}?cmd=changeset;node=\{node\|short\}
jerojasro@336	940 description:
jerojasro@336	941 \{desc\|tabindent\|strip\}
jerojasro@336	942
jerojasro@336	943 [web]
jerojasro@336	944 baseurl = http://hg.example.com/
jerojasro@336	945 \end{codesample2}
jerojasro@336	946
jerojasro@336	947 This will produce a message that looks like the following:
jerojasro@336	948 \begin{codesample2}
jerojasro@336	949 X-Hg-Repo: tests/slave
jerojasro@336	950 Subject: tests/slave: Handle error case when slave has no buffers
jerojasro@336	951 Date: Wed, 2 Aug 2006 15:25:46 -0700 (PDT)
jerojasro@336	952
jerojasro@336	953 changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave
jerojasro@336	954 details: http://hg.example.com/tests/slave?cmd=changeset;node=3cba9bfe74b5
jerojasro@336	955 description:
jerojasro@336	956 Handle error case when slave has no buffers
jerojasro@336	957 diffs (54 lines):
jerojasro@336	958
jerojasro@336	959 diff -r 9d95df7cf2ad -r 3cba9bfe74b5 include/tests.h
jerojasro@336	960 --- a/include/tests.h Wed Aug 02 15:19:52 2006 -0700
jerojasro@336	961 +++ b/include/tests.h Wed Aug 02 15:25:26 2006 -0700
jerojasro@336	962 @@ -212,6 +212,15 @@ static __inline__ void test_headers(void *h)
jerojasro@336	963 [...snip...]
jerojasro@336	964 \end{codesample2}
jerojasro@336	965
jerojasro@336	966 \subsubsection{Testing and troubleshooting}
jerojasro@336	967
jerojasro@336	968 Do not forget that by default, the \hgext{notify} extension \emph{will
jerojasro@336	969 not send any mail} until you explicitly configure it to do so, by
jerojasro@336	970 setting \rcitem{notify}{test} to \texttt{false}. Until you do that,
jerojasro@336	971 it simply prints the message it \emph{would} send.
jerojasro@336	972
jerojasro@336	973 \section{Information for writers of hooks}
jerojasro@336	974 \label{sec:hook:ref}
jerojasro@336	975
jerojasro@336	976 \subsection{In-process hook execution}
jerojasro@336	977
jerojasro@336	978 An in-process hook is called with arguments of the following form:
jerojasro@336	979 \begin{codesample2}
jerojasro@336	980 def myhook(ui, repo, **kwargs):
jerojasro@336	981 pass
jerojasro@336	982 \end{codesample2}
jerojasro@336	983 The \texttt{ui} parameter is a \pymodclass{mercurial.ui}{ui} object.
jerojasro@336	984 The \texttt{repo} parameter is a
jerojasro@336	985 \pymodclass{mercurial.localrepo}{localrepository} object. The
jerojasro@336	986 names and values of the \texttt{**kwargs} parameters depend on the
jerojasro@336	987 hook being invoked, with the following common features:
jerojasro@336	988 \begin{itemize}
jerojasro@336	989 \item If a parameter is named \texttt{node} or
jerojasro@336	990 \texttt{parent\emph{N}}, it will contain a hexadecimal changeset ID.
jerojasro@336	991 The empty string is used to represent ``null changeset ID'' instead
jerojasro@336	992 of a string of zeroes.
jerojasro@336	993 \item If a parameter is named \texttt{url}, it will contain the URL of
jerojasro@336	994 a remote repository, if that can be determined.
jerojasro@336	995 \item Boolean-valued parameters are represented as Python
jerojasro@336	996 \texttt{bool} objects.
jerojasro@336	997 \end{itemize}
jerojasro@336	998
jerojasro@336	999 An in-process hook is called without a change to the process's working
jerojasro@336	1000 directory (unlike external hooks, which are run in the root of the
jerojasro@336	1001 repository). It must not change the process's working directory, or
jerojasro@336	1002 it will cause any calls it makes into the Mercurial API to fail.
jerojasro@336	1003
jerojasro@336	1004 If a hook returns a boolean ``false'' value, it is considered to have
jerojasro@336	1005 succeeded. If it returns a boolean ``true'' value or raises an
jerojasro@336	1006 exception, it is considered to have failed. A useful way to think of
jerojasro@336	1007 the calling convention is ``tell me if you fail''.
jerojasro@336	1008
jerojasro@336	1009 Note that changeset IDs are passed into Python hooks as hexadecimal
jerojasro@336	1010 strings, not the binary hashes that Mercurial's APIs normally use. To
jerojasro@336	1011 convert a hash from hex to binary, use the
jerojasro@336	1012 \pymodfunc{mercurial.node}{bin} function.
jerojasro@336	1013
jerojasro@336	1014 \subsection{External hook execution}
jerojasro@336	1015
jerojasro@336	1016 An external hook is passed to the shell of the user running Mercurial.
jerojasro@336	1017 Features of that shell, such as variable substitution and command
jerojasro@336	1018 redirection, are available. The hook is run in the root directory of
jerojasro@336	1019 the repository (unlike in-process hooks, which are run in the same
jerojasro@336	1020 directory that Mercurial was run in).
jerojasro@336	1021
jerojasro@336	1022 Hook parameters are passed to the hook as environment variables. Each
jerojasro@336	1023 environment variable's name is converted in upper case and prefixed
jerojasro@336	1024 with the string ``\texttt{HG\_}''. For example, if the name of a
jerojasro@336	1025 parameter is ``\texttt{node}'', the name of the environment variable
jerojasro@336	1026 representing that parameter will be ``\texttt{HG\_NODE}''.
jerojasro@336	1027
jerojasro@336	1028 A boolean parameter is represented as the string ``\texttt{1}'' for
jerojasro@336	1029 ``true'', ``\texttt{0}'' for ``false''. If an environment variable is
jerojasro@336	1030 named \envar{HG\_NODE}, \envar{HG\_PARENT1} or \envar{HG\_PARENT2}, it
jerojasro@336	1031 contains a changeset ID represented as a hexadecimal string. The
jerojasro@336	1032 empty string is used to represent ``null changeset ID'' instead of a
jerojasro@336	1033 string of zeroes. If an environment variable is named
jerojasro@336	1034 \envar{HG\_URL}, it will contain the URL of a remote repository, if
jerojasro@336	1035 that can be determined.
jerojasro@336	1036
jerojasro@336	1037 If a hook exits with a status of zero, it is considered to have
jerojasro@336	1038 succeeded. If it exits with a non-zero status, it is considered to
jerojasro@336	1039 have failed.
jerojasro@336	1040
jerojasro@336	1041 \subsection{Finding out where changesets come from}
jerojasro@336	1042
jerojasro@336	1043 A hook that involves the transfer of changesets between a local
jerojasro@336	1044 repository and another may be able to find out information about the
jerojasro@336	1045 ``far side''. Mercurial knows \emph{how} changes are being
jerojasro@336	1046 transferred, and in many cases \emph{where} they are being transferred
jerojasro@336	1047 to or from.
jerojasro@336	1048
jerojasro@336	1049 \subsubsection{Sources of changesets}
jerojasro@336	1050 \label{sec:hook:sources}
jerojasro@336	1051
jerojasro@336	1052 Mercurial will tell a hook what means are, or were, used to transfer
jerojasro@336	1053 changesets between repositories. This is provided by Mercurial in a
jerojasro@336	1054 Python parameter named \texttt{source}, or an environment variable named
jerojasro@336	1055 \envar{HG\_SOURCE}.
jerojasro@336	1056
jerojasro@336	1057 \begin{itemize}
jerojasro@336	1058 \item[\texttt{serve}] Changesets are transferred to or from a remote
jerojasro@336	1059 repository over http or ssh.
jerojasro@336	1060 \item[\texttt{pull}] Changesets are being transferred via a pull from
jerojasro@336	1061 one repository into another.
jerojasro@336	1062 \item[\texttt{push}] Changesets are being transferred via a push from
jerojasro@336	1063 one repository into another.
jerojasro@336	1064 \item[\texttt{bundle}] Changesets are being transferred to or from a
jerojasro@336	1065 bundle.
jerojasro@336	1066 \end{itemize}
jerojasro@336	1067
jerojasro@336	1068 \subsubsection{Where changes are going---remote repository URLs}
jerojasro@336	1069 \label{sec:hook:url}
jerojasro@336	1070
jerojasro@336	1071 When possible, Mercurial will tell a hook the location of the ``far
jerojasro@336	1072 side'' of an activity that transfers changeset data between
jerojasro@336	1073 repositories. This is provided by Mercurial in a Python parameter
jerojasro@336	1074 named \texttt{url}, or an environment variable named \envar{HG\_URL}.
jerojasro@336	1075
jerojasro@336	1076 This information is not always known. If a hook is invoked in a
jerojasro@336	1077 repository that is being served via http or ssh, Mercurial cannot tell
jerojasro@336	1078 where the remote repository is, but it may know where the client is
jerojasro@336	1079 connecting from. In such cases, the URL will take one of the
jerojasro@336	1080 following forms:
jerojasro@336	1081 \begin{itemize}
jerojasro@336	1082 \item \texttt{remote:ssh:\emph{ip-address}}---remote ssh client, at
jerojasro@336	1083 the given IP address.
jerojasro@336	1084 \item \texttt{remote:http:\emph{ip-address}}---remote http client, at
jerojasro@336	1085 the given IP address. If the client is using SSL, this will be of
jerojasro@336	1086 the form \texttt{remote:https:\emph{ip-address}}.
jerojasro@336	1087 \item Empty---no information could be discovered about the remote
jerojasro@336	1088 client.
jerojasro@336	1089 \end{itemize}
jerojasro@336	1090
jerojasro@336	1091 \section{Hook reference}
jerojasro@336	1092
jerojasro@336	1093 \subsection{\hook{changegroup}---after remote changesets added}
jerojasro@336	1094 \label{sec:hook:changegroup}
jerojasro@336	1095
jerojasro@336	1096 This hook is run after a group of pre-existing changesets has been
jerojasro@336	1097 added to the repository, for example via a \hgcmd{pull} or
jerojasro@336	1098 \hgcmd{unbundle}. This hook is run once per operation that added one
jerojasro@336	1099 or more changesets. This is in contrast to the \hook{incoming} hook,
jerojasro@336	1100 which is run once per changeset, regardless of whether the changesets
jerojasro@336	1101 arrive in a group.
jerojasro@336	1102
jerojasro@336	1103 Some possible uses for this hook include kicking off an automated
jerojasro@336	1104 build or test of the added changesets, updating a bug database, or
jerojasro@336	1105 notifying subscribers that a repository contains new changes.
jerojasro@336	1106
jerojasro@336	1107 Parameters to this hook:
jerojasro@336	1108 \begin{itemize}
jerojasro@336	1109 \item[\texttt{node}] A changeset ID. The changeset ID of the first
jerojasro@336	1110 changeset in the group that was added. All changesets between this
jerojasro@336	1111 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
jerojasro@336	1112 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
jerojasro@336	1113 \item[\texttt{source}] A string. The source of these changes. See
jerojasro@336	1114 section~\ref{sec:hook:sources} for details.
jerojasro@336	1115 \item[\texttt{url}] A URL. The location of the remote repository, if
jerojasro@336	1116 known. See section~\ref{sec:hook:url} for more information.
jerojasro@336	1117 \end{itemize}
jerojasro@336	1118
jerojasro@336	1119 See also: \hook{incoming} (section~\ref{sec:hook:incoming}),
jerojasro@336	1120 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}),
jerojasro@336	1121 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
jerojasro@336	1122
jerojasro@336	1123 \subsection{\hook{commit}---after a new changeset is created}
jerojasro@336	1124 \label{sec:hook:commit}
jerojasro@336	1125
jerojasro@336	1126 This hook is run after a new changeset has been created.
jerojasro@336	1127
jerojasro@336	1128 Parameters to this hook:
jerojasro@336	1129 \begin{itemize}
jerojasro@336	1130 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
jerojasro@336	1131 committed changeset.
jerojasro@336	1132 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
jerojasro@336	1133 parent of the newly committed changeset.
jerojasro@336	1134 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
jerojasro@336	1135 parent of the newly committed changeset.
jerojasro@336	1136 \end{itemize}
jerojasro@336	1137
jerojasro@336	1138 See also: \hook{precommit} (section~\ref{sec:hook:precommit}),
jerojasro@336	1139 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
jerojasro@336	1140
jerojasro@336	1141 \subsection{\hook{incoming}---after one remote changeset is added}
jerojasro@336	1142 \label{sec:hook:incoming}
jerojasro@336	1143
jerojasro@336	1144 This hook is run after a pre-existing changeset has been added to the
jerojasro@336	1145 repository, for example via a \hgcmd{push}. If a group of changesets
jerojasro@336	1146 was added in a single operation, this hook is called once for each
jerojasro@336	1147 added changeset.
jerojasro@336	1148
jerojasro@336	1149 You can use this hook for the same purposes as the \hook{changegroup}
jerojasro@336	1150 hook (section~\ref{sec:hook:changegroup}); it's simply more convenient
jerojasro@336	1151 sometimes to run a hook once per group of changesets, while other
jerojasro@336	1152 times it's handier once per changeset.
jerojasro@336	1153
jerojasro@336	1154 Parameters to this hook:
jerojasro@336	1155 \begin{itemize}
jerojasro@336	1156 \item[\texttt{node}] A changeset ID. The ID of the newly added
jerojasro@336	1157 changeset.
jerojasro@336	1158 \item[\texttt{source}] A string. The source of these changes. See
jerojasro@336	1159 section~\ref{sec:hook:sources} for details.
jerojasro@336	1160 \item[\texttt{url}] A URL. The location of the remote repository, if
jerojasro@336	1161 known. See section~\ref{sec:hook:url} for more information.
jerojasro@336	1162 \end{itemize}
jerojasro@336	1163
jerojasro@336	1164 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}) \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}), \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
jerojasro@336	1165
jerojasro@336	1166 \subsection{\hook{outgoing}---after changesets are propagated}
jerojasro@336	1167 \label{sec:hook:outgoing}
jerojasro@336	1168
jerojasro@336	1169 This hook is run after a group of changesets has been propagated out
jerojasro@336	1170 of this repository, for example by a \hgcmd{push} or \hgcmd{bundle}
jerojasro@336	1171 command.
jerojasro@336	1172
jerojasro@336	1173 One possible use for this hook is to notify administrators that
jerojasro@336	1174 changes have been pulled.
jerojasro@336	1175
jerojasro@336	1176 Parameters to this hook:
jerojasro@336	1177 \begin{itemize}
jerojasro@336	1178 \item[\texttt{node}] A changeset ID. The changeset ID of the first
jerojasro@336	1179 changeset of the group that was sent.
jerojasro@336	1180 \item[\texttt{source}] A string. The source of the of the operation
jerojasro@336	1181 (see section~\ref{sec:hook:sources}). If a remote client pulled
jerojasro@336	1182 changes from this repository, \texttt{source} will be
jerojasro@336	1183 \texttt{serve}. If the client that obtained changes from this
jerojasro@336	1184 repository was local, \texttt{source} will be \texttt{bundle},
jerojasro@336	1185 \texttt{pull}, or \texttt{push}, depending on the operation the
jerojasro@336	1186 client performed.
jerojasro@336	1187 \item[\texttt{url}] A URL. The location of the remote repository, if
jerojasro@336	1188 known. See section~\ref{sec:hook:url} for more information.
jerojasro@336	1189 \end{itemize}
jerojasro@336	1190
jerojasro@336	1191 See also: \hook{preoutgoing} (section~\ref{sec:hook:preoutgoing})
jerojasro@336	1192
jerojasro@336	1193 \subsection{\hook{prechangegroup}---before starting to add remote changesets}
jerojasro@336	1194 \label{sec:hook:prechangegroup}
jerojasro@336	1195
jerojasro@336	1196 This controlling hook is run before Mercurial begins to add a group of
jerojasro@336	1197 changesets from another repository.
jerojasro@336	1198
jerojasro@336	1199 This hook does not have any information about the changesets to be
jerojasro@336	1200 added, because it is run before transmission of those changesets is
jerojasro@336	1201 allowed to begin. If this hook fails, the changesets will not be
jerojasro@336	1202 transmitted.
jerojasro@336	1203
jerojasro@336	1204 One use for this hook is to prevent external changes from being added
jerojasro@336	1205 to a repository. For example, you could use this to ``freeze'' a
jerojasro@336	1206 server-hosted branch temporarily or permanently so that users cannot
jerojasro@336	1207 push to it, while still allowing a local administrator to modify the
jerojasro@336	1208 repository.
jerojasro@336	1209
jerojasro@336	1210 Parameters to this hook:
jerojasro@336	1211 \begin{itemize}
jerojasro@336	1212 \item[\texttt{source}] A string. The source of these changes. See
jerojasro@336	1213 section~\ref{sec:hook:sources} for details.
jerojasro@336	1214 \item[\texttt{url}] A URL. The location of the remote repository, if
jerojasro@336	1215 known. See section~\ref{sec:hook:url} for more information.
jerojasro@336	1216 \end{itemize}
jerojasro@336	1217
jerojasro@336	1218 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
jerojasro@336	1219 \hook{incoming} (section~\ref{sec:hook:incoming}), ,
jerojasro@336	1220 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
jerojasro@336	1221
jerojasro@336	1222 \subsection{\hook{precommit}---before starting to commit a changeset}
jerojasro@336	1223 \label{sec:hook:precommit}
jerojasro@336	1224
jerojasro@336	1225 This hook is run before Mercurial begins to commit a new changeset.
jerojasro@336	1226 It is run before Mercurial has any of the metadata for the commit,
jerojasro@336	1227 such as the files to be committed, the commit message, or the commit
jerojasro@336	1228 date.
jerojasro@336	1229
jerojasro@336	1230 One use for this hook is to disable the ability to commit new
jerojasro@336	1231 changesets, while still allowing incoming changesets. Another is to
jerojasro@336	1232 run a build or test, and only allow the commit to begin if the build
jerojasro@336	1233 or test succeeds.
jerojasro@336	1234
jerojasro@336	1235 Parameters to this hook:
jerojasro@336	1236 \begin{itemize}
jerojasro@336	1237 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
jerojasro@336	1238 parent of the working directory.
jerojasro@336	1239 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
jerojasro@336	1240 parent of the working directory.
jerojasro@336	1241 \end{itemize}
jerojasro@336	1242 If the commit proceeds, the parents of the working directory will
jerojasro@336	1243 become the parents of the new changeset.
jerojasro@336	1244
jerojasro@336	1245 See also: \hook{commit} (section~\ref{sec:hook:commit}),
jerojasro@336	1246 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
jerojasro@336	1247
jerojasro@336	1248 \subsection{\hook{preoutgoing}---before starting to propagate changesets}
jerojasro@336	1249 \label{sec:hook:preoutgoing}
jerojasro@336	1250
jerojasro@336	1251 This hook is invoked before Mercurial knows the identities of the
jerojasro@336	1252 changesets to be transmitted.
jerojasro@336	1253
jerojasro@336	1254 One use for this hook is to prevent changes from being transmitted to
jerojasro@336	1255 another repository.
jerojasro@336	1256
jerojasro@336	1257 Parameters to this hook:
jerojasro@336	1258 \begin{itemize}
jerojasro@336	1259 \item[\texttt{source}] A string. The source of the operation that is
jerojasro@336	1260 attempting to obtain changes from this repository (see
jerojasro@336	1261 section~\ref{sec:hook:sources}). See the documentation for the
jerojasro@336	1262 \texttt{source} parameter to the \hook{outgoing} hook, in
jerojasro@336	1263 section~\ref{sec:hook:outgoing}, for possible values of this
jerojasro@336	1264 parameter.
jerojasro@336	1265 \item[\texttt{url}] A URL. The location of the remote repository, if
jerojasro@336	1266 known. See section~\ref{sec:hook:url} for more information.
jerojasro@336	1267 \end{itemize}
jerojasro@336	1268
jerojasro@336	1269 See also: \hook{outgoing} (section~\ref{sec:hook:outgoing})
jerojasro@336	1270
jerojasro@336	1271 \subsection{\hook{pretag}---before tagging a changeset}
jerojasro@336	1272 \label{sec:hook:pretag}
jerojasro@336	1273
jerojasro@336	1274 This controlling hook is run before a tag is created. If the hook
jerojasro@336	1275 succeeds, creation of the tag proceeds. If the hook fails, the tag is
jerojasro@336	1276 not created.
jerojasro@336	1277
jerojasro@336	1278 Parameters to this hook:
jerojasro@336	1279 \begin{itemize}
jerojasro@336	1280 \item[\texttt{local}] A boolean. Whether the tag is local to this
jerojasro@336	1281 repository instance (i.e.~stored in \sfilename{.hg/localtags}) or
jerojasro@336	1282 managed by Mercurial (stored in \sfilename{.hgtags}).
jerojasro@336	1283 \item[\texttt{node}] A changeset ID. The ID of the changeset to be tagged.
jerojasro@336	1284 \item[\texttt{tag}] A string. The name of the tag to be created.
jerojasro@336	1285 \end{itemize}
jerojasro@336	1286
jerojasro@336	1287 If the tag to be created is revision-controlled, the \hook{precommit}
jerojasro@336	1288 and \hook{pretxncommit} hooks (sections~\ref{sec:hook:commit}
jerojasro@336	1289 and~\ref{sec:hook:pretxncommit}) will also be run.
jerojasro@336	1290
jerojasro@336	1291 See also: \hook{tag} (section~\ref{sec:hook:tag})
jerojasro@336	1292
jerojasro@336	1293 \subsection{\hook{pretxnchangegroup}---before completing addition of
jerojasro@336	1294 remote changesets}
jerojasro@336	1295 \label{sec:hook:pretxnchangegroup}
jerojasro@336	1296
jerojasro@336	1297 This controlling hook is run before a transaction---that manages the
jerojasro@336	1298 addition of a group of new changesets from outside the
jerojasro@336	1299 repository---completes. If the hook succeeds, the transaction
jerojasro@336	1300 completes, and all of the changesets become permanent within this
jerojasro@336	1301 repository. If the hook fails, the transaction is rolled back, and
jerojasro@336	1302 the data for the changesets is erased.
jerojasro@336	1303
jerojasro@336	1304 This hook can access the metadata associated with the almost-added
jerojasro@336	1305 changesets, but it should not do anything permanent with this data.
jerojasro@336	1306 It must also not modify the working directory.
jerojasro@336	1307
jerojasro@336	1308 While this hook is running, if other Mercurial processes access this
jerojasro@336	1309 repository, they will be able to see the almost-added changesets as if
jerojasro@336	1310 they are permanent. This may lead to race conditions if you do not
jerojasro@336	1311 take steps to avoid them.
jerojasro@336	1312
jerojasro@336	1313 This hook can be used to automatically vet a group of changesets. If
jerojasro@336	1314 the hook fails, all of the changesets are ``rejected'' when the
jerojasro@336	1315 transaction rolls back.
jerojasro@336	1316
jerojasro@336	1317 Parameters to this hook:
jerojasro@336	1318 \begin{itemize}
jerojasro@336	1319 \item[\texttt{node}] A changeset ID. The changeset ID of the first
jerojasro@336	1320 changeset in the group that was added. All changesets between this
jerojasro@336	1321 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
jerojasro@336	1322 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
jerojasro@336	1323 \item[\texttt{source}] A string. The source of these changes. See
jerojasro@336	1324 section~\ref{sec:hook:sources} for details.
jerojasro@336	1325 \item[\texttt{url}] A URL. The location of the remote repository, if
jerojasro@336	1326 known. See section~\ref{sec:hook:url} for more information.
jerojasro@336	1327 \end{itemize}
jerojasro@336	1328
jerojasro@336	1329 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
jerojasro@336	1330 \hook{incoming} (section~\ref{sec:hook:incoming}),
jerojasro@336	1331 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup})
jerojasro@336	1332
jerojasro@336	1333 \subsection{\hook{pretxncommit}---before completing commit of new changeset}
jerojasro@336	1334 \label{sec:hook:pretxncommit}
jerojasro@336	1335
jerojasro@336	1336 This controlling hook is run before a transaction---that manages a new
jerojasro@336	1337 commit---completes. If the hook succeeds, the transaction completes
jerojasro@336	1338 and the changeset becomes permanent within this repository. If the
jerojasro@336	1339 hook fails, the transaction is rolled back, and the commit data is
jerojasro@336	1340 erased.
jerojasro@336	1341
jerojasro@336	1342 This hook can access the metadata associated with the almost-new
jerojasro@336	1343 changeset, but it should not do anything permanent with this data. It
jerojasro@336	1344 must also not modify the working directory.
jerojasro@336	1345
jerojasro@336	1346 While this hook is running, if other Mercurial processes access this
jerojasro@336	1347 repository, they will be able to see the almost-new changeset as if it
jerojasro@336	1348 is permanent. This may lead to race conditions if you do not take
jerojasro@336	1349 steps to avoid them.
jerojasro@336	1350
jerojasro@336	1351 Parameters to this hook:
jerojasro@336	1352 \begin{itemize}
jerojasro@336	1353 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
jerojasro@336	1354 committed changeset.
jerojasro@336	1355 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
jerojasro@336	1356 parent of the newly committed changeset.
jerojasro@336	1357 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
jerojasro@336	1358 parent of the newly committed changeset.
jerojasro@336	1359 \end{itemize}
jerojasro@336	1360
jerojasro@336	1361 See also: \hook{precommit} (section~\ref{sec:hook:precommit})
jerojasro@336	1362
jerojasro@336	1363 \subsection{\hook{preupdate}---before updating or merging working directory}
jerojasro@336	1364 \label{sec:hook:preupdate}
jerojasro@336	1365
jerojasro@336	1366 This controlling hook is run before an update or merge of the working
jerojasro@336	1367 directory begins. It is run only if Mercurial's normal pre-update
jerojasro@336	1368 checks determine that the update or merge can proceed. If the hook
jerojasro@336	1369 succeeds, the update or merge may proceed; if it fails, the update or
jerojasro@336	1370 merge does not start.
jerojasro@336	1371
jerojasro@336	1372 Parameters to this hook:
jerojasro@336	1373 \begin{itemize}
jerojasro@336	1374 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
jerojasro@336	1375 working directory is to be updated to. If the working directory is
jerojasro@336	1376 being merged, it will not change this parent.
jerojasro@336	1377 \item[\texttt{parent2}] A changeset ID. Only set if the working
jerojasro@336	1378 directory is being merged. The ID of the revision that the working
jerojasro@336	1379 directory is being merged with.
jerojasro@336	1380 \end{itemize}
jerojasro@336	1381
jerojasro@336	1382 See also: \hook{update} (section~\ref{sec:hook:update})
jerojasro@336	1383
jerojasro@336	1384 \subsection{\hook{tag}---after tagging a changeset}
jerojasro@336	1385 \label{sec:hook:tag}
jerojasro@336	1386
jerojasro@336	1387 This hook is run after a tag has been created.
jerojasro@336	1388
jerojasro@336	1389 Parameters to this hook:
jerojasro@336	1390 \begin{itemize}
jerojasro@336	1391 \item[\texttt{local}] A boolean. Whether the new tag is local to this
jerojasro@336	1392 repository instance (i.e.~stored in \sfilename{.hg/localtags}) or
jerojasro@336	1393 managed by Mercurial (stored in \sfilename{.hgtags}).
jerojasro@336	1394 \item[\texttt{node}] A changeset ID. The ID of the changeset that was
jerojasro@336	1395 tagged.
jerojasro@336	1396 \item[\texttt{tag}] A string. The name of the tag that was created.
jerojasro@336	1397 \end{itemize}
jerojasro@336	1398
jerojasro@336	1399 If the created tag is revision-controlled, the \hook{commit} hook
jerojasro@336	1400 (section~\ref{sec:hook:commit}) is run before this hook.
jerojasro@336	1401
jerojasro@336	1402 See also: \hook{pretag} (section~\ref{sec:hook:pretag})
jerojasro@336	1403
jerojasro@336	1404 \subsection{\hook{update}---after updating or merging working directory}
jerojasro@336	1405 \label{sec:hook:update}
jerojasro@336	1406
jerojasro@336	1407 This hook is run after an update or merge of the working directory
jerojasro@336	1408 completes. Since a merge can fail (if the external \command{hgmerge}
jerojasro@336	1409 command fails to resolve conflicts in a file), this hook communicates
jerojasro@336	1410 whether the update or merge completed cleanly.
jerojasro@336	1411
jerojasro@336	1412 \begin{itemize}
jerojasro@336	1413 \item[\texttt{error}] A boolean. Indicates whether the update or
jerojasro@336	1414 merge completed successfully.
jerojasro@336	1415 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
jerojasro@336	1416 working directory was updated to. If the working directory was
jerojasro@336	1417 merged, it will not have changed this parent.
jerojasro@336	1418 \item[\texttt{parent2}] A changeset ID. Only set if the working
jerojasro@336	1419 directory was merged. The ID of the revision that the working
jerojasro@336	1420 directory was merged with.
jerojasro@336	1421 \end{itemize}
jerojasro@336	1422
jerojasro@336	1423 See also: \hook{preupdate} (section~\ref{sec:hook:preupdate})
jerojasro@336	1424
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