Mercurial offers a powerful mechanism to let you perform automated actions in response to events that occur in a repository. In some cases, you can even control Mercurial’s response to those events.
The name Mercurial uses for one of these actions is a hook. Hooks are called “triggers” in some revision control systems, but the two names refer to the same idea.
Here is a brief list of the hooks that Mercurial supports. We will revisit each of these hooks in more detail later, in Information for Writers of Hooks.
Each of the hooks whose description begins with the word “Controlling” has the ability to determine whether an activity can proceed. If the hook succeeds, the activity may proceed; if it fails, the activity is either not permitted or undone, depending on the hook.
changegroup
: This is
run after a group of changesets has been brought into the repository
from elsewhere.
commit
: This is run
after a new changeset has been created in the local
repository.
incoming
: This is
run once for each new changeset that is brought into the repository
from elsewhere. Notice the difference from changegroup
, which is run once per
group of changesets brought in.
outgoing
: This is
run after a group of changesets has been transmitted from this
repository.
prechangegroup
: This
is run before starting to bring a group of changesets into the
repository.
precommit
:
Controlling. This is run before starting a commit.
preoutgoing
:
Controlling. This is run before starting to transmit a group of
changesets from this repository.
pretxnchangegroup
:
Controlling. This is run after a group of changesets has been
brought into the local repository from another, but before the
transaction completes that will make the changes permanent in the
repository.
pretxncommit
:
Controlling. This is run after a new changeset has been created in
the local repository, but before the transaction completes that will
make it permanent.
preupdate
:
Controlling. This is run before starting an update or merge of the
working directory.
update
: This is run
after an update or merge of the working directory has
finished.
When you run a Mercurial command in a repository, and the command causes a hook to run, that hook runs on your system, under your user account, with your privilege level. Since hooks are arbitrary pieces of executable code, you should treat them with an appropriate level of suspicion. Do not install a hook unless you are confident that you know who created it and what it does.
In some cases, you may be exposed to hooks that you did not install yourself. If you work with Mercurial on an unfamiliar system, Mercurial will run hooks defined in that system’s global ~/.hgrc file.
If you are working with a repository owned by another
user, Mercurial can run hooks defined in that user’s repository, but
it will still run them as “you.” For example, if you
hg pull from that repository, and its
.hg/hgrc defines a local outgoing
hook, that hook will run under your
user account, even though you don’t own that repository.
This only applies if you are pulling from a
repository on a local or network filesystem. If you’re pulling over
http or ssh, any outgoing
hook will
run under whatever account is executing the server process on the
server.
To see what hooks are defined in a repository, use the hg showconfig hooks command. If you are working in one repository but talking to another that you do not own (e.g., using hg pull or hg incoming), remember that it is the other repository’s hooks you should be checking, not your own.
In Mercurial, hooks are not revision controlled, and do not propagate when you clone, or pull from, a repository. The reason for this is simple: a hook is a completely arbitrary piece of executable code. It runs under your user identity, with your privilege level, on your machine.
It would be extremely reckless for any distributed revision control system to implement revision-controlled hooks, as this would offer an easily exploitable way to subvert the accounts of users of the revision control system.
Since Mercurial does not propagate hooks, if you are collaborating with other people on a common project, you should not assume that they are using the same Mercurial hooks as you are, or that theirs are correctly configured. You should document the hooks you expect people to use.
In a corporate intranet, this is somewhat easier to control, as you can for example provide a “standard” installation of Mercurial on an NFS filesystem, and use a site-wide ~/.hgrc file to define hooks that all users will see. However, this too has its limits; see below.
Mercurial allows you to override a hook definition by redefining the hook. You can disable it by setting its value to the empty string, or change its behavior as you wish.
If you deploy a system- or site-wide ~/.hgrc file that defines some hooks, you should thus understand that your users can disable or override those hooks.
Sometimes you may want to enforce a policy that you do not want others to be able to work around. For example, you may have a requirement that every changeset must pass a rigorous set of tests. Defining this requirement via a hook in a site-wide ~/.hgrc won’t work for remote users on laptops, and of course local users can subvert it at will by overriding the hook.
Instead, you can set up your policies for use of Mercurial so that people are expected to propagate changes through a well-known “canonical” server that you have locked down and configured appropriately.
One way to do this is via a combination of social engineering and technology. Set up a restricted-access account; users can push changes over the network to repositories managed by this account, but they cannot log into the account and run normal shell commands. In this scenario, a user can commit a changeset that contains any old garbage they want.
When someone pushes a changeset to the server that everyone pulls from, the server will test the changeset before it accepts it as permanent, and reject it if it fails to pass the test suite. If people only pull changes from this filtering server, it will serve to ensure that all changes that people pull have been automatically vetted.
It is easy to write a Mercurial hook. Let’s start with
a hook that runs when you finish a hg
commit, and simply prints the hash of the changeset you just
created. The hook is called commit
.
All hooks follow the pattern in this example.
$
hg init hook-test
$
cd hook-test
$
echo '[hooks]' >> .hg/hgrc
$
echo 'commit = echo committed $HG_NODE' >> .hg/hgrc
$
cat .hg/hgrc
[hooks] commit = echo committed $HG_NODE$
echo a > a
$
hg add a
$
hg commit -m 'testing commit hook'
committed ffec6cdc3a79c21f42d9e0c8fa460ea72c1748e5
You add an entry to the hooks
section of your ~/.hgrc. On the left is the name of the event to trigger on; on
the right is the action to take. As you can see, you can run an
arbitrary shell command in a hook. Mercurial passes extra information to
the hook using environment variables (look for HG_NODE
in
the example).
Quite often, you will want to define more than one hook for a particular kind of event, as shown below.
$
echo 'commit.when = echo -n "date of commit: "; date' >> .hg/hgrc
$
echo a >> a
$
hg commit -m 'i have two hooks'
committed e2b474b33334b9c332deeaa7a211f36b03266ac9 date of commit: Tue May 5 06:44:39 GMT 2009
Mercurial lets you do this by adding an
extension to the end of a hook’s name. You extend a hook’s name by giving the name of the
hook, followed by a full stop (the . character), followed by some more
text of your choosing. For example, Mercurial will run both
commit.foo
and commit.bar
when
the commit
event occurs.
To give a well-defined order of execution when there
are multiple hooks defined for an event, Mercurial sorts hooks by
extension, and executes the hook commands in this sorted order. In the
above example, it will execute commit.bar
before
commit.foo
, and commit
before
both.
It is a good idea to use a somewhat descriptive extension when you define a new hook. This will help you to remember what the hook was for. If the hook fails, you’ll get an error message that contains the hook name and extension, so using a descriptive extension could give you an immediate hint as to why the hook failed (see Controlling Whether an Activity Can Proceed for an example).
In our earlier examples, we used the commit
hook, which is run after a commit has
completed. This is one of several Mercurial hooks that run after
an activity finishes. Such hooks have no way of influencing the
activity itself.
Mercurial defines a number of events that occur before an activity starts, or after it starts but before it finishes. Hooks that trigger on these events have the added ability to choose whether the activity can continue, or will abort.
The pretxncommit
hook
runs after a commit has all but completed. In other words, the metadata representing the changeset
has been written out to disk, but the transaction has not yet been
allowed to complete. The pretxncommit
hook has the ability to decide whether the transaction can complete,
or must be rolled back.
If the pretxncommit
hook exits with a status code of zero, the transaction is allowed to
complete, the commit finishes, and the commit
hook is run. If the pretxncommit
hook exits with a non-zero status
code, the transaction is rolled back, the metadata representing the
changeset is erased, and the commit
hook is not run.
$
cat check_bug_id
#!/bin/sh # check that a commit comment mentions a numeric bug id hg log -r $1 --template {desc} | grep -q "<bug *[0-9]"$
echo 'pretxncommit.bug_id_required = ./check_bug_id $HG_NODE' >> .hg/hgrc
$
echo a >> a
$
hg commit -m 'i am not mentioning a bug id'
transaction abort! rollback completed abort: pretxncommit.bug_id_required hook exited with status 1$
hg commit -m 'i refer you to bug 666'
committed 8e23f09593369ce73361346d89e875e152432402 date of commit: Tue May 5 06:44:39 GMT 2009
The hook in the example above checks that a commit comment contains a bug ID. If it does, the commit can complete. If not, the commit is rolled back.
When you are writing a hook, you might find it useful
to run Mercurial either with the -v
option, or the verbose
config item set to
“true.” When you do so, Mercurial will print a message
before it calls each hook.
You can write a hook either as a normal program—typically a shell script—or as a Python function that is executed within the Mercurial process.
Writing a hook as an external program has the advantage that it requires no knowledge of Mercurial’s internals. You can call normal Mercurial commands to get any added information you need. The trade-off is that external hooks are slower than in-process hooks.
An in-process Python hook has complete access to the Mercurial API, and does not “shell out” to another process, so it is inherently faster than an external hook. It is also easier to obtain much of the information that a hook requires by using the Mercurial API than by running Mercurial commands.
If you are comfortable with Python or require high performance, writing your hooks in Python may be a good choice. However, when you have a straightforward hook to write and you don’t need to care about performance (probably the majority of hooks), a shell script is perfectly fine.
Mercurial calls each hook with a set of well-defined parameters. In Python, a parameter is passed as a keyword argument to your hook function. For an external program, a parameter is passed as an environment variable.
Whether your hook is written in Python or as a shell
script, the hook-specific parameter names and values will be the same.
A boolean parameter will be represented as a boolean value in Python,
but as the number 1 (for “true”) or 0 (for
“false”) as an environment variable for an external hook.
If a hook parameter is named foo
, the keyword
argument for a Python hook will also be named foo
,
while the environment variable for an external hook will be named
HG_FOO
.
A hook that executes successfully must exit with a status of zero if external, or return boolean “false” if in-process. Failure is indicated with a non-zero exit status from an external hook, or an in-process hook returning boolean “true.” If an in-process hook raises an exception, the hook is considered to have failed.
For a hook that controls whether an activity can proceed, zero/false means “allow,” while non-zero/true/exception means “deny.”
When you define an external hook in your ~/.hgrc and the hook is run, its value is passed to your shell, which interprets it. This means that you can use normal shell constructs in the body of the hook.
An executable hook is always run with its current directory set to a repository’s root directory.
Each hook parameter is passed in as an environment
variable; the name is upper cased, and prefixed with the string
HG_
.
With the exception of hook parameters, Mercurial does not set or modify any environment variables when running a hook. This is useful to remember if you are writing a site-wide hook that may be run by a number of different users with differing environment variables set. In multi-user situations, you should not rely on environment variables being set to the values you have in your environment when testing the hook.
The ~/.hgrc syntax for defining an in-process hook is slightly different than for an executable hook. The value of the hook must start with the text python:, and continue with the fully qualified name of a callable object to use as the hook’s value.
The module in which a hook lives is automatically
imported when a hook is run. As long as you have the module name and
PYTHONPATH
right, it should “just
work.”
The following ~/.hgrc example snippet illustrates the syntax and meaning of the notions we just described.
[hooks] commit.example = python:mymodule.submodule.myhook
When Mercurial runs the
commit.example
hook, it imports
mymodule.submodule
, looks for the callable object
named myhook
, and calls it.
The simplest in-process hook does nothing, but illustrates the basic shape of the hook API:
def myhook(ui, repo, **kwargs): pass
The first argument to a Python hook is always a
ui
object. The second is
a repository object; at the moment, it is always an instance of
localrepository
.
Following these two arguments are other keyword arguments. Which ones
are passed in depends on the hook being called, but a hook can ignore
arguments it doesn’t care about by dropping them into a keyword
argument dict, as with **kwargs
above.
It’s hard to imagine a useful commit message being
very short. The simple pretxncommit
hook of the example below will prevent you from committing a changeset
with a message that is less than ten bytes long.
$
cat .hg/hgrc
[hooks] pretxncommit.msglen = test `hg tip --template {desc} | wc -c` -ge 10$
echo a > a
$
hg add a
$
hg commit -A -m 'too short'
transaction abort! rollback completed abort: pretxncommit.msglen hook exited with status 1$
hg commit -A -m 'long enough'
An interesting use of a commit-related hook is to help you to write cleaner code. A simple example of “cleaner code” is the dictum that a change should not add any new lines of text that contain “trailing whitespace.” Trailing whitespace is a series of space and tab characters at the end of a line of text. In most cases, trailing whitespace is unnecessary, invisible noise, but it is occasionally problematic, and people often prefer to get rid of it.
You can use either the precommit
or pretxncommit
hook to tell whether you have a
trailing whitespace problem. If you use the precommit
hook, the hook will not know which files you are committing, so it
will have to check every modified file in the repository for trailing
white space. If you want to commit a change to just the file
foo, but the file bar
contains trailing whitespace, doing a check in the precommit
hook will prevent you from committing
foo due to the problem with
bar. This doesn’t seem right.
Should you choose the pretxncommit
hook, the check won’t occur until
just before the transaction for the commit completes. This will allow
you to check for problems only in the exact files that are being
committed. However, if you entered the commit message interactively
and the hook fails, the transaction will roll back; you’ll have to
re-enter the commit message after you fix the trailing whitespace and
run hg commit again.
$
cat .hg/hgrc
[hooks] pretxncommit.whitespace = hg export tip | (! egrep -q '^+.*[ ]$')$
echo 'a ' > a
$
hg commit -A -m 'test with trailing whitespace'
adding a transaction abort! rollback completed abort: pretxncommit.whitespace hook exited with status 1$
echo 'a' > a
$
hg commit -A -m 'drop trailing whitespace and try again'
In this example, we introduce a simple pretxncommit
hook that checks for trailing
whitespace. This hook is short, but not very helpful. It exits with an
error status if a change adds a line with trailing whitespace to any
file, but does not print any information that might help us to
identify the offending file or line. It also has the nice property of
not paying attention to unmodified lines; only lines that introduce
new trailing whitespace cause problems.
#!/usr/bin/env python # # save as .hg/check_whitespace.py and make executable import re def trailing_whitespace(difflines): # linenum, header = 0, False for line in difflines: if header: # remember the name of the file that this diff affects m = re.match(r'(?:---|+++) ([^ ]+)', line) if m and m.group(1) != '/dev/null': filename = m.group(1).split('/', 1)[-1] if line.startswith('+++ '): header = False continue if line.startswith('diff '): header = True continue # hunk header - save the line number m = re.match(r'@@ -d+,d+ +(d+),', line) if m: linenum = int(m.group(1)) continue # hunk body - check for an added line with trailing whitespace m = re.match(r'+.*s$', line) if m: yield filename, linenum if line and line[0] in ' +': linenum += 1 if __name__ == '__main__': import os, sys added = 0 for filename, linenum in trailing_whitespace(os.popen('hg export tip')): print >> sys.stderr, ('%s, line %d: trailing whitespace added' % (filename, linenum)) added += 1 if added: # save the commit message so we don't need to retype it os.system('hg tip --template "{desc}" > .hg/commit.save') print >> sys.stderr, 'commit message saved to .hg/commit.save' sys.exit(1)
The above version is much more complex, but also more
useful. It parses a unified diff to see if any lines add trailing
whitespace, and prints the name of the file and the line number of
each such occurrence. Even better, if the change adds trailing
whitespace, this hook saves the commit comment and prints the name of
the saved file before exiting and telling Mercurial to roll the
transaction back, so you can use the -l
filename
option to hg commit
to reuse the saved commit message once you’ve corrected the
problem.
$
cat .hg/hgrc
[hooks] pretxncommit.whitespace = .hg/check_whitespace.py$
echo 'a ' >> a
$
hg commit -A -m 'add new line with trailing whitespace'
a, line 2: trailing whitespace added commit message saved to .hg/commit.save transaction abort! rollback completed abort: pretxncommit.whitespace hook exited with status 1$
sed -i 's, *$,,' a
$
hg commit -A -m 'trimmed trailing whitespace'
a, line 2: trailing whitespace added commit message saved to .hg/commit.save transaction abort! rollback completed abort: pretxncommit.whitespace hook exited with status 1
As a final aside, note in the example above the use of sed’s in-place editing feature to get rid of trailing whitespace from a file. This is concise and useful enough that I will reproduce it here (using perl for good measure).
perl -pi -e 's,s+$,,' filename
Mercurial ships with several bundled hooks. You can find them in the hgext directory of a Mercurial source tree. If you are using a Mercurial binary package, the hooks will be located in the hgext directory of wherever your package installer put Mercurial.
The acl
extension
lets you control which remote users are allowed to push changesets to
a networked server. You can protect any portion of a repository (including
the entire repo), so that a specific remote user can push changes that
do not affect the protected portion.
This extension implements access control based on the identity of the user performing a push, not on who committed the changesets they’re pushing. It makes sense to use this hook only if you have a locked-down server environment that authenticates remote users, and you want to be sure that only specific users are allowed to push changes to that server.
In order to manage incoming changesets, the
acl
hook must be used as a pretxnchangegroup
hook. This lets it see which
files are modified by each incoming changeset, and roll back a group
of changesets if they modify “forbidden” files. For
example:
[hooks] pretxnchangegroup.acl = python:hgext.acl.hook
The acl
extension
is configured using three sections.
The acl
section
has only one entry, sources
, which
lists the sources of incoming changesets that the hook should pay
attention to. You don’t normally need to configure this
section.
serve
:
Control incoming changesets that are arriving from a remote
repository over http or ssh. This is the default value of sources
, and usually the only setting
you’ll need for this configuration item.
pull
: Control
incoming changesets that are arriving via a pull from a local
repository.
push
: Control
incoming changesets that are arriving via a push from a local
repository.
bundle
:
Control incoming changesets that are arriving from another
repository via a bundle.
The acl.allow
section controls the users
that are allowed to add changesets to the repository. If this
section is not present, all users that are not explicitly denied are
allowed. If this section is present, all users that are not
explicitly allowed are denied (so an empty section means that all
users are denied).
The acl.deny
section determines which users are denied from adding changesets to
the repository. If this section is not present or is empty, no users
are denied.
The syntaxes for the acl.allow
and acl.deny
sections are identical. On the
left of each entry is a glob pattern that matches files or
directories, relative to the root of the repository; on the right, a
username.
In the following example, the user
docwriter
can only push changes to the docs subtree of the repository, while
intern
can push changes to any file or directory
except source/sensitive.
[acl.allow] docs/** = docwriter [acl.deny] source/sensitive/** = intern
If you want to test the acl
hook, run it with Mercurial’s debugging
output enabled. Since you’ll probably be running it on a server
where it’s not convenient (or sometimes impossible) to pass in the
--debug
option, don’t forget
that you can enable debugging output in your ~/.hgrc:
[ui] debug = true
With this enabled, the acl
hook will print enough information to
let you figure out why it is allowing or forbidding pushes from
specific users.
The bugzilla
extension adds a comment to a Bugzilla bug whenever it finds a
reference to that bug ID in a commit comment. You can install this hook on a shared server, so that
any time a remote user pushes changes to this server, the hook gets
run.
The hook adds a comment to the bug that looks like this (you can configure the contents of the comment—see below):
Changeset aad8b264143a, made by Joe User <[email protected]> in the frobnitz repository, refers to this bug. For complete details, see http://hg.domain.com/frobnitz?cmd=changeset;node=aad8b264143a Changeset description: Fix bug 10483 by guarding against some NULL pointers
The value of this hook is that it automates the process of updating a bug any time a changeset refers to it. If you configure the hook properly, it makes it easy for people to browse straight from a Bugzilla bug to a changeset that refers to that bug.
You can use the code in this hook as a starting point for some more exotic Bugzilla integration recipes. Here are a few possibilities:
Require that every changeset pushed to the server
have a valid bug ID in its commit comment. In this case, you’d
want to configure the hook as a pretxncommit
hook. This would allow the hook
to reject changes that didn’t contain bug IDs.
Allow incoming changesets to automatically modify the state of a bug, as well as simply adding a comment. For example, the hook could recognize the string “fixed bug 31337” as indicating that it should update the state of bug 31337 to “requires testing.”
You should configure this hook in your server’s
~/.hgrc as an incoming
hook, for example as follows:
[hooks] incoming.bugzilla = python:hgext.bugzilla.hook
Because of the specialized nature of this hook, and because Bugzilla was not written with this kind of integration in mind, configuring this hook is a somewhat involved process.
Before you begin, you must install the MySQL bindings for Python on the host(s) where you’ll be running the hook. If this is not available as a binary package for your system, you can download it from http://sourceforge.net/projects/mysql-python.
Configuration information for this hook lives in
the bugzilla
section of your
~/.hgrc.
version
:
The version of Bugzilla installed on the server. The database schema that Bugzilla uses changes
occasionally, so this hook has to know exactly which schema to
use.
host
:
The hostname of the MySQL server that stores your Bugzilla
data. The database must be configured to allow
connections from whatever host you are running the bugzilla
hook on.
user
:
The username with which to connect to the MySQL
server. The database must be configured to allow this
user to connect from whatever host you are running the bugzilla
hook on. This user must be able
to access and modify Bugzilla tables. The default value of this
item is bugs
, which is the standard name of
the Bugzilla user in a MySQL database.
password
: The MySQL password for
the user you configured above. This is stored as plain text, so you should make
sure that unauthorized users cannot read the ~/.hgrc file where you store this
information.
db
: The
name of the Bugzilla database on the MySQL server. The default value of this item is
bugs
, which is the standard name of the MySQL
database where Bugzilla stores its data.
notify
:
If you want Bugzilla to send out a notification email to
subscribers after this hook has added a comment to a bug, you
will need this hook to run a command whenever it updates the
database. The command to run depends on where you have
installed Bugzilla, but it will typically look something like
this, if you have Bugzilla installed in /var/www/html/bugzilla:
cd /var/www/html/bugzilla && ./processmail %s [email protected]
The Bugzilla processmail
program expects to be given a bug ID (the hook replaces %s with
the bug ID) and an email address. It also expects to be able to write to some files
in the directory that it runs in. If Bugzilla and this hook are
not installed on the same machine, you will need to find a way
to run processmail
on the server where
Bugzilla is installed.
By default, the bugzilla
hook tries to use the email address
of a changeset’s committer as the Bugzilla username with which to
update a bug. If this does not suit your needs, you can map
committer email addresses to Bugzilla usernames using a usermap
section.
Each item in the usermap
section contains an email
address on the left, and a Bugzilla username on the right:
[usermap] [email protected] = jane
You can either keep the usermap
data in a normal ~/.hgrc, or tell the bugzilla
hook to read the information from
an external usermap file. In the latter case,
you can store usermap data by itself in (for
example) a user-modifiable repository. This makes it possible to let
your users maintain their own usermap
entries. The main ~/.hgrc file might look like this:
# regular hgrc file refers to external usermap file [bugzilla] usermap = /home/hg/repos/userdata/bugzilla-usermap.conf
while the usermap file that it refers to might look like this:
# bugzilla-usermap.conf - inside a hg repository [usermap] [email protected] = steph
You can configure the text that this hook adds as a
comment; you specify it in the form of a Mercurial template. Several
~/.hgrc entries (still in the
bugzilla
section) control this
behavior.
strip
: The number of leading
path elements to strip from a repository’s pathname to construct
a partial path for a URL. For example, if the repositories on your server
live under /home/hg/repos, and you have a
repository whose path is /home/hg/repos/app/tests, then
setting strip
to 4
will
give a partial path of app/tests. The hook will make this
partial path available when expanding a template, as
webroot
.
template
: The text of the
template to use. In addition to the usual changeset-related
variables, this template can use hgweb
(the
value of the hgweb
configuration item above)
and webroot
(the path constructed using
strip
above).
In addition, you can add a baseurl
item to the web
section of your ~/.hgrc. The bugzilla
hook will make this available when
expanding a template, as the base string to use when constructing a
URL that will let users browse from a Bugzilla comment to view a
changeset. For example:
[web] baseurl = http://hg.domain.com/
Here is an example set of bugzilla
hook config information:
[bugzilla] host = bugzilla.example.com password = mypassword version = 2.16 # server-side repos live in /home/hg/repos, so strip 4 leading # separators strip = 4 hgweb = http://hg.example.com/ usermap = /home/hg/repos/notify/bugzilla.conf template = Changeset {node|short}, made by {author} in the {webroot} repo, refers to this bug. For complete details, see {hgweb}{webroot}?cmd=changeset;node={node|short} Changeset description: {desc|tabindent}
The most common problems with configuring the
bugzilla
hook relate to running
Bugzilla’s processmail script and mapping
committer names to usernames.
Recall from Configuring the bugzilla hook that the user that runs the Mercurial process on the server is also the one that will run the processmail script. The processmail script sometimes causes Bugzilla to write to files in its configuration directory, and Bugzilla’s configuration files are usually owned by the user that your web server runs under.
You can cause processmail to be run with the suitable user’s identity using the sudo command. Here is an example entry for a sudoers file:
hg_user = (httpd_user) NOPASSWD: /var/www/html/bugzilla/processmail-wrapper %s
This allows the hg_user
to run a
processmail-wrapper program under the identity
of httpd_user
.
This indirection through a wrapper script is necessary, because processmail expects to be run with its current directory set to wherever you installed Bugzilla; you can’t specify that kind of constraint in a sudoers file. The contents of the wrapper script are simple:
#!/bin/sh cd `dirname $0` && ./processmail "$1" [email protected]
It doesn’t seem to matter what email address you pass to processmail.
If your usermap
is not set up correctly, users
will see an error message from the bugzilla
hook when they push changes to the
server. The error message will look like this:
cannot find bugzilla user id for [email protected]
What this means is that the committer’s address,
[email protected]
, is not a valid
Bugzilla username, nor does it have an entry in your usermap
that maps it to a valid Bugzilla
username.
Although Mercurial’s built-in web server provides RSS
feeds of changes in every repository, many people prefer to receive
change notifications via email. The notify
hook lets
you send out notifications to a set of email addresses whenever
changesets arrive that those subscribers are interested in.
As with the bugzilla
hook, the notify
hook is template
driven, so you can customize the contents of the notification messages
that it sends.
By default, the notify
hook includes a diff of every changeset
that it sends out; you can limit the size of the diff, or turn this
feature off entirely. It is useful for letting subscribers review
changes immediately, rather than clicking to follow a URL.
You can set up the notify
hook to send one email message per
incoming changeset, or one per incoming group of changesets (all
those that arrived in a single pull or push).
[hooks] # send one email per group of changes changegroup.notify = python:hgext.notify.hook # send one email per change incoming.notify = python:hgext.notify.hook
Configuration information for this hook lives in
the notify
section of the
~/.hgrc file.
test
: By
default, this hook does not send out email at all; instead, it
prints the message that it would
send. Set this item to false
to
allow email to be sent. The reason that sending of email is
turned off by default is that it takes several tries to
configure this extension exactly as you would like, and it would
be bad form to spam subscribers with a number of
“broken” notifications while you debug your
configuration.
config
:
The path to a configuration file that contains subscription
information. This is kept separate from the main ~/.hgrc so that you can maintain it in
a repository of its own. People can then clone that repository,
update their subscriptions, and push the changes back to your
server.
strip
: The
number of leading path separator characters to strip from a
repository’s path, when deciding whether a repository has
subscribers. For example, if the repositories on your server
live in /home/hg/repos,
and notify
is considering a
repository named /home/hg/repos/shared/test, setting
strip
to
4
will cause notify
to trim the path it considers
down to shared/test, and
it will match subscribers against that.
template
:
The template text to use when sending messages. This specifies both the contents of the message
header and its body.
maxdiff
:
The maximum number of lines of diff data to append to the end of
a message. If a diff is longer than this, it is truncated.
By default, this is set to 300. Set this to 0 to omit diffs from
notification emails.
sources
: A
list of sources of changesets to consider. This lets you limit notify
to only sending out email about
changes that remote users pushed into this repository via a
server, for example. See Sources of changesets for
the sources you can specify here.
If you set the baseurl
item in the web
section, you can use it in a template;
it will be available as webroot
.
Here is an example set of notify
configuration information:
[notify] # really send email test = false # subscriber data lives in the notify repo config = /home/hg/repos/notify/notify.conf # repos live in /home/hg/repos on server, so strip 4 "/" chars strip = 4 template = X-Hg-Repo: {webroot} Subject: {webroot}: {desc|firstline|strip} From: {author} changeset {node|short} in {root} details: {baseurl}{webroot}?cmd=changeset;node={node|short} description: {desc|tabindent|strip} [web] baseurl = http://hg.example.com/
This will produce a message that looks like the following:
X-Hg-Repo: tests/slave Subject: tests/slave: Handle error case when slave has no buffers Date: Wed, 2 Aug 2006 15:25:46 -0700 (PDT) changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave details: http://hg.example.com/tests/slave?cmd=changeset;node=3cba9bfe74b5 description: Handle error case when slave has no buffers diffs (54 lines): diff -r 9d95df7cf2ad -r 3cba9bfe74b5 include/tests.h --- a/include/tests.h Wed Aug 02 15:19:52 2006 -0700 +++ b/include/tests.h Wed Aug 02 15:25:26 2006 -0700 @@ -212,6 +212,15 @@ static __inline__ void test_headers(void *h) [...snip...]
An in-process hook is called with arguments of the following form:
def myhook(ui, repo, **kwargs): pass
The ui
parameter is a ui
object. The
repo
parameter is a localrepository
object.
The names and values of the **kwargs
parameters
depend on the hook being invoked, with the following common
features:
If a parameter is named node
or parentN
, it will contain a hexadecimal
changeset ID. The empty string is used to represent “null
changeset ID” instead of a string of zeros.
If a parameter is named url
,
it will contain the URL of a remote repository, if that can be
determined.
Boolean-valued parameters are represented as
Python bool
objects.
An in-process hook is called without a change to the process’s working directory (unlike external hooks, which are run in the root of the repository). It must not change the process’s working directory, or it will cause any calls it makes into the Mercurial API to fail.
If a hook returns a boolean “false” value, it is considered to have succeeded. If it returns a boolean “true” value or raises an exception, it is considered to have failed. A useful way to think of the calling convention is “tell me if you fail.”
Note that changeset IDs are passed into Python hooks
as hexadecimal strings, not the binary hashes that Mercurial’s APIs
normally use. To convert a hash from hex to binary, use the
bin
function.
An external hook is passed to the shell of the user running Mercurial. Features of that shell, such as variable substitution and command redirection, are available. The hook is run in the root directory of the repository (unlike in-process hooks, which are run in the same directory that Mercurial was run in).
Hook parameters are passed to the hook as environment
variables. Each environment variable’s name is converted to uppercase
and prefixed with the string HG_
. For example, if the name of a parameter is
node, the name of the environment variable representing that parameter
will be HG_NODE.
A boolean parameter is represented as the string 1
for true, 0 for false. If an environment variable is named
HG_NODE
, HG_PARENT1
, or
HG_PARENT2
, it contains a changeset ID represented as a
hexadecimal string. The empty string is used to represent “null
changeset ID” instead of a string of zeros. If an environment
variable is named HG_URL
, it will contain the URL of a
remote repository, if that can be determined.
If a hook exits with a status of zero, it is considered to have succeeded. If it exits with a non-zero status, it is considered to have failed.
A hook that involves the transfer of changesets between a local repository and another may be able to find out information about the “far side.” Mercurial knows how changes are being transferred, and in many cases where they are being transferred to or from.
Mercurial will tell a hook what means are, or were,
used to transfer changesets between repositories. This is provided
by Mercurial in a Python parameter named source
,
or an environment variable named HG_SOURCE
.
serve
: Changesets are
transferred to or from a remote repository over http or
ssh.
pull
: Changesets are being
transferred via a pull from one repository into another.
push
: Changesets are being
transferred via a push from one repository into another.
bundle
: Changesets are being
transferred to or from a bundle.
When possible, Mercurial will tell a hook the
location of the “far side” of an activity that
transfers changeset data between repositories. This is provided by Mercurial in a Python parameter
named url
, or an environment variable named
HG_URL
.
This information is not always known. If a hook is invoked in a repository that is being served via http or ssh, Mercurial cannot tell where the remote repository is, but it may know where the client is connecting from. In such cases, the URL will take one of the following forms:
This hook is run after a group of pre-existing
changesets has been added to the repository, for example via hg pull or hg
unbundle. This hook is run once per operation that added one or
more changesets. This is in contrast to the incoming
hook, which is run once per changeset,
regardless of whether the changesets arrived in a group.
Some possible uses for this hook include kicking off an automated build or test of the added changesets, updating a bug database, or notifying subscribers that a repository contains new changes.
node
: A changeset ID. The
changeset ID of the first changeset in the group that was added.
All changesets between this and tip
,
inclusive, were added by a single hg
pull, hg push, or
hg unbundle.
source
: A string. The source
of these changes. See Sources of changesets for
details.
url
: A URL. The location of
the remote repository, if known. See Where changes are going—remote repository URLs for more information.
See also: incoming
(incoming—After One Remote Changeset Is Added), prechangegroup
(prechangegroup—Before Starting to Add Remote Changesets), pretxnchangegroup
(pretxnchangegroup—Before Completing Addition of Remote
Changesets)
This hook is run after a new changeset has been created.
See also: precommit
(precommit—Before Starting to Commit a Changeset), pretxncommit
(pretxncommit—Before Completing Commit of New Changeset)
This hook is run after a pre-existing changeset has been added to the repository, for example via a hg push. If a group of changesets was added in a single operation, this hook is called once for each added changeset.
You can use this hook for the same purposes as the
changegroup
hook (changegroup—After Remote Changesets Added); it’s simply more convenient
sometimes to run a hook once per group of changesets, while other
times it’s handier once per changeset.
source
: A string. The source
of these changes. See Sources of changesets for
details.
url
: A URL. The location of
the remote repository, if known. See Where changes are going—remote repository URLs for more information.
See also: changegroup
(changegroup—After Remote Changesets Added), prechangegroup
(prechangegroup—Before Starting to Add Remote Changesets), pretxnchangegroup
(pretxnchangegroup—Before Completing Addition of Remote
Changesets)
This hook is run after a group of changesets has been propagated out of this repository, for example by a hg push or hg bundle command.
One possible use for this hook is to notify administrators that changes have been pulled.
node
: A changeset ID. The
changeset ID of the first changeset of the group that was
sent.
source
: A string. The source
of the operation (see Sources of changesets). If a
remote client pulled changes from this repository,
source
will be serve
. If the
client that obtained changes from this repository was local,
source
will be bundle
,
pull
, or push
, depending on
the operation the client performed.
url
: A URL. The location of
the remote repository, if known. See Where changes are going—remote repository URLs for more information.
See also: preoutgoing
(preoutgoing—Before Starting to Propagate Changesets)
This controlling hook is run before Mercurial begins to add a group of changesets from another repository.
This hook does not have any information about the changesets to be added, because it is run before transmission of those changesets is allowed to begin. If this hook fails, the changesets will not be transmitted.
One use for this hook is to prevent external changes from being added to a repository. For example, you could use this to “freeze” a server-hosted branch temporarily or permanently so that users cannot push to it, while still allowing a local administrator to modify the repository.
source
: A string. The source
of these changes. See Sources of changesets for
details.
url
: A URL. The location of
the remote repository, if known. See Where changes are going—remote repository URLs for more information.
See also: changegroup
(changegroup—After Remote Changesets Added), incoming
(incoming—After One Remote Changeset Is Added),
pretxnchangegroup
(pretxnchangegroup—Before Completing Addition of Remote
Changesets)
This hook is run before Mercurial begins to commit a new changeset. It is run before Mercurial has any of the metadata for the commit, such as the files to be committed, the commit message, or the commit date.
One use for this hook is to disable the ability to commit new changesets, while still allowing incoming changesets. Another is to run a build or test, and only allow the commit to begin if the build or test succeeds.
If the commit proceeds, the parents of the working directory will become the parents of the new changeset.
See also: commit
(commit—After a New Changeset Is Created), pretxncommit
(pretxncommit—Before Completing Commit of New Changeset)
This hook is invoked before Mercurial knows the identities of the changesets to be transmitted.
One use for this hook is to prevent changes from being transmitted to another repository.
source
: A string. The source
of the operation that is attempting to obtain changes from this
repository (see Sources of changesets). See the
documentation for the source
parameter to the
outgoing
hook (in outgoing—After Changesets Are Propagated) for possible values of this
parameter.
url
: A URL. The location of
the remote repository, if known. See Where changes are going—remote repository URLs for more information.
See also: outgoing
(outgoing—After Changesets Are Propagated)
This controlling hook is run before a tag is created. If the hook succeeds, creation of the tag proceeds. If the hook fails, the tag is not created.
If the tag to be created is revision-controlled, the
precommit
and pretxncommit
hooks (commit—After a New Changeset Is Created and pretxncommit—Before Completing Commit of New Changeset) will also be run.
See also: tag
(tag—After Tagging a Changeset)
This controlling hook is run before a transaction—that manages the addition of a group of new changesets from outside the repository—completes. If the hook succeeds, the transaction completes, and all of the changesets become permanent within this repository. If the hook fails, the transaction is rolled back, and the data for the changesets is erased.
This hook can access the metadata associated with the almost-added changesets, but it should not do anything permanent with this data. It must also not modify the working directory.
While this hook is running, if other Mercurial processes access this repository, they will be able to see the almost-added changesets as if they were permanent. This may lead to race conditions if you do not take steps to avoid them.
This hook can be used to automatically vet a group of changesets. If the hook fails, all of the changesets are “rejected” when the transaction rolls back.
node
: A changeset ID. The
changeset ID of the first changeset in the group that was added.
All changesets between this and tip
,
inclusive, were added by a single hg
pull, hg push, or
hg unbundle.
source
: A string. The source
of these changes. See Sources of changesets for
details.
url
: A URL. The location of
the remote repository, if known. See Where changes are going—remote repository URLs for more information.
See also: changegroup
(changegroup—After Remote Changesets Added), incoming
(incoming—After One Remote Changeset Is Added),
prechangegroup
(prechangegroup—Before Starting to Add Remote Changesets)
This controlling hook is run before a transaction—that manages a new commit—completes. If the hook succeeds, the transaction completes and the changeset becomes permanent within this repository. If the hook fails, the transaction is rolled back, and the commit data is erased.
This hook can access the metadata associated with the almost-new changeset, but it should not do anything permanent with this data. It also must not modify the working directory.
While this hook is running, if other Mercurial processes access this repository, they will be able to see the almost-new changeset as if it were permanent. This may lead to race conditions if you do not take steps to avoid them.
See also: precommit
(precommit—Before Starting to Commit a Changeset)
This controlling hook is run before an update or merge of the working directory begins. It is run only if Mercurial’s normal pre-update checks determine that the update or merge can proceed. If the hook succeeds, the update or merge may proceed; if it fails, the update or merge does not start.
parent1
: A changeset ID. The
ID of the parent that the working directory is to be updated to.
If the working directory is being merged, it will not change this
parent.
parent2
: A changeset ID. Only
set if the working directory is being merged. The ID of the
revision that the working directory is being merged with.
See also: update
(update—After Updating or Merging Working Directory)
This hook is run after a tag has been created.
If the created tag is revision-controlled, the
commit
hook (see commit—After a New Changeset Is Created) is run before this hook.
See also: pretag
(pretag—Before Tagging a Changeset)
This hook is run after an update or merge of the working directory completes. Since a merge can fail (if the external hgmerge command fails to resolve conflicts in a file), this hook communicates whether the update or merge completed cleanly.
error
: A boolean. Indicates
whether the update or merge completed successfully.
parent1
: A changeset ID. The
ID of the parent that the working directory was updated to. If the
working directory was merged, it will not have changed this
parent.
parent2
: A changeset ID. Only
set if the working directory was merged. The ID of the revision
that the working directory was merged with.
See also: preupdate
(preupdate—Before Updating or Merging Working Directory)
3.16.79.65