Chapter 10. Handling repository events with hooksChapter 10. Handling repository events with hooksTable of ContentsMercurial 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.An overview of hooks in MercurialHere is a brief list of the hooks that Mercurial
supports. We will revisit each of these hooks in more detail
later, in .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
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.
Controlling. This is run before creating a tag.
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.
tag: This is run
after a tag is created.
update: This is
run after an update or merge of the working directory has
Hooks and securityHooks are run with your privilegesWhen 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
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
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
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.
Hooks do not propagateIn Mercurial, hooks are not revision controlled, and do
not propagate when you clone, or pull from, a repository.
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.
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
However, thi see below.
Hooks can be overriddenMercurial 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.
Ensuring that critical hooks are runSometimes 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
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.
A short tutorial on using hooksIt 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
commit = echo committed $HG_NODE
$ echo a & a
$ hg add a
$ hg commit -m 'testing commit hook'
committed 8cc1c7ddb98a9b6d7687a1faa62cf7b32dbe9e03
You add an entry to the hooks section of your ~/.hgrc.
On the left is the name of
the on the right is the action to take.
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).
Performing multiple actions per eventQuite 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 669d3ac83eae08ced498beb5cf1d
date of commit: Tue May
5 06:55:36 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
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
for an example).
Controlling whether an activity can proceedIn 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
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
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
and the commit hook is run.
If the pretxncommit hook exits with a
non-zero status code, the transa the
metadata representing the and the
commit hook is not run.
$ cat check_bug_id
# 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 052ec7f32e83e2aaab
date of commit: Tue May
5 06:55:36 GMT 2009
The hook in the example above checks that a commit comment
contains a bug ID.
If it does, the commit can complete.
not, the commit is rolled back.
Writing your own hooksWhen 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
When you do so, Mercurial will print a
message before it calls each hook.
Choosing how your hook should runYou 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.
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
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
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.
Hook parametersMercurial 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
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.
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.
Hook return values and activity controlA 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
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”.
Writing an external hookWhen you define an external hook in your ~/.hgrc and the hook is run, its
value is passed to your shell, which interprets it.
means that you can use normal shell constructs in the body of
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
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.
Telling Mercurial to use an in-process hookThe ~/.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.
So long as you have the module name and
PYTHONPATH right, it should “just
The following ~/.hgrc
example snippet illustrates the syntax and meaning of the
notions we just described.
commit.example = python:mymodule.submodule.myhookWhen Mercurial runs the commit.example
hook, it imports mymodule.submodule, looks
for the callable object named myhook, and
Writing an in-process hookThe simplest in-process hook does nothing, but illustrates
the basic shape of the hook API:
def myhook(ui, repo, **kwargs):
passThe first argument to a Python hook is always a ui object.
The second
is 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.
Some hook examplesWriting meaningful commit messagesIt'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
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'
Checking for trailing whitespaceAn 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.
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.
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 the
exact files that are being committed.
However, if you entered
the commit message interactively and the hook fails, the
transa you'll have to re-enter the commit
message after you fix the trailing whitespace and run hg commit again.
$ cat .hg/hgrc
pretxncommit.whitespace = hg export tip | (! egrep -q '^\+.*[ \t]$')
$ echo 'a ' & a
$ hg commit -A -m 'test with trailing whitespace'
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
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 only lines that introduce new
trailing whitespace cause problems.
#!/usr/bin/env python
# save as .hg/check_whitespace.py and make executable
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'(?:---|\+\+\+) ([^\t]+)', line)
if m and m.group(1) != '/dev/null':
filename = m.group(1).split('/', 1)[-1]
if line.startswith('+++ '):
header = False
if line.startswith('diff '):
header = True
# hunk header - save the line number
m = re.match(r'@@ -\d+,\d+ \+(\d+),', line)
linenum = int(m.group(1))
# hunk body - check for an added line with trailing whitespace
m = re.match(r'\+.*\s$', line)
yield filename, linenum
if line and line[0] in ' +':
linenum += 1
if __name__ == '__main__':
import os, sys
for filename, linenum in trailing_whitespace(os.popen('hg export tip')):
print && sys.stderr, ('%s, line %d: trailing whitespace added' %
(filename, linenum))
added += 1
# 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
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 save 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
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+$,,' filenameBundled hooksMercurial 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.
acl—access
control for parts of a repositoryThe 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
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.
Configuring the acl
hookIn order to manage incoming changesets, the acl hook must be used as a
pretxnchangegroup hook.
lets it see which files are modified by each incoming
changeset, and roll back a group of changesets if they
modify “forbidden” files.
pretxnchangegroup.acl = python:hgext.acl.hookThe 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.
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.
Control incoming changesets that are arriving via a pull
from a local repository.
Control incoming changesets that are arriving via a push
from a local repository.
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
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
on the right, a user name.
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/** = internTesting and troubleshootingIf 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
possible) to pass in the --debug option, don't forget
that you can enable debugging output in your ~/.hgrc:
debug = trueWith this enabled, the acl hook will print enough
information to let you figure out why it is allowing or
forbidding pushes from specific users.
bugzilla—integration with
BugzillaThe 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.
It 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
&joe.& in the frobnitz repository, refers
to this bug. For complete details, see
/frobnitz?cmd=node=aad8b264143a
Changeset description: Fix bug 10483 by guarding against some
NULL pointersThe value of this hook is that it automates the process of
updating a bug any time a changeset refers to it.
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.
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
Allow incoming changesets to automatically
modify the state of a bug, as well as
simply adding a comment.
For example, the hook could
recognise the string “fixed bug 31337” as
indicating that it should update the state of bug 31337 to
“requires testing”.
Configuring the bugzilla
hookYou should configure this hook in your server's
~/.hgrc as an incoming hook, for example as
incoming.bugzilla = python:hgext.bugzilla.hookBecause of the specialised 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
[web: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.
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.
must be able to access and modify Bugzilla tables.
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.
stored as plain text, so you should make sure that
unauthorised users cannot read the ~/.hgrc file where you
store this information.
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
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
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.
Mapping committer names to Bugzilla user namesBy default, the bugzilla hook tries to use the
email address of a changeset's committer as the Bugzilla
user name with which to update a bug.
If this does not suit
your needs, you can map committer email addresses to
Bugzilla user names using a usermap section.
Each item in the usermap section contains an
email address on the left, and a Bugzilla user name on the
jane. = janeYou can either keep the usermap data in a normal
~/.hgrc, or tell the
bugzilla hook to read the
information from an external usermap
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.
~/.hgrc file might look
like this:
# regular hgrc file refers to external usermap file
[bugzilla]
usermap = /home/hg/repos/userdata/bugzilla-usermap.confWhile the usermap file that it
refers to might look like this:
# bugzilla-usermap.conf - inside a hg repository
= stephConfiguring the text that gets added to a bugYou can configure the text that this hook adds as a
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 path
name 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.
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.
baseurl = /Here is an example set of bugzilla hook config information.
[bugzilla]
password = mypassword version = 2.16
# server-side repos live in /home/hg/repos, so strip 4 leading
# separators
usermap = /home/hg/repos/notify/bugzilla.conf
template = Changeset {node|short}, made by {author} in the {webroot}
repo, refers to this bug.\n
For complete details, see
{hgweb}{webroot}?cmd=node={node|short}\n
Changeset description:\n
\t{desc|tabindent}Testing and troubleshootingThe most common problems with configuring the bugzilla hook relate to running
Bugzilla's processmail script and
mapping committer names to user names.
Recall from
above that the user
that runs the Mercurial process on the server is also the
one that will run the processmail
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
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 %sThis allows the hg_user 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
B you can't specify that kind of constraint in a
sudoers file.
The contents of the
wrapper script are simple:
cd `dirname $0` && ./processmail "$1" 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 john.q.What this means is that the committer's address,
john.q., is not a valid
Bugzilla user name, nor does it have an entry in your
usermap that maps it to
a valid Bugzilla user name.
notify—send email
notificationsAlthough 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 customise the contents of the
notification messages that it sends.
By default, the notify
hook includes a diff of every changes you
can limit the size of the diff, or turn this feature off
It is useful for letting subscribers review changes
immediately, rather than clicking to follow a URL.
Configuring the notify
hookYou 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
# send one email per group of changes
changegroup.notify = python:hgext.notify.hook
# send one email per change
incoming.notify = python:hgext.notify.hookConfiguration information for this hook lives in the
notify section of a
~/.hgrc file.
By default, this hook does not s
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.
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.
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
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
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.
for the sources you
can specify here.
If you set the baseurl
item in the web section,
it will be available as
Here is an example set of notify configuration information.
# 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
template = X-Hg-Repo: {webroot}\n
Subject: {webroot}: {desc|firstline|strip}\n
From: {author}
changeset {node|short} in {root}
\n\ndetails:
{baseurl}{webroot}?cmd=node={node|short}
description: {desc|tabindent|strip}
/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 :46 -0700 (PDT)
changeset 3cba9bfe74b5 in /home/hg/repos/tests/slave
/tests/slave?cmd=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
+++ b/include/tests.h
Wed Aug 02 15:25:26
@@ -212,6 +212,15 @@ static __inline__
void test_headers(void *h)
[...snip...]Testing and troubleshootingDo not forget that by default, the notify extension will not
send any mail until you explicitly configure it to do so,
by setting test to
Until you do that, it simply
prints the message it would send.
Information for writers of hooksIn-process hook executionAn in-process hook is called with arguments of the
following form:
def myhook(ui, repo, **kwargs): passThe ui parameter is a ui object. The
repo parameter is a localrepository
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 zeroes.
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.
External hook executionAn 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.
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 in
upper case and prefixed with the string
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 zeroes.
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.
Finding out where changesets come fromA hook that involves the transfer of changesets between a
local repository and another may be able to find out
information about the “far side”.
knows how changes are being transferred,
and in many cases where they are being
transferred to or from.
Sources of changesetsMercurial will tell a hook what means are, or were, used
to transfer changesets between repositories.
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
pull: Changesets are
being transferred via a pull from one repository into
push: Changesets are
being transferred via a push from one repository into
bundle: Changesets are
being transferred to or from a bundle.
Where changes are going—remote repository
URLsWhen 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
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.
such cases, the URL will take one of the following forms:
remote:ssh:1.2.3.4—remote
ssh client, at the IP address
remote:http:1.2.3.4—remote
http client, at the IP address
If the client is using SSL,
this will be of the form
remote:https:1.2.3.4.
Empty—no information could be
discovered about the remote client.
Hook referencechangegroup—after
remote changesets addedThis hook is run after a group of pre-existing changesets
has been added to the repository, for example via a hg pull or hg
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
arrive 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.
Parameters to this hook:
node: A changeset ID.
changeset ID of the first changeset in the group that was
All changesets between this and
tip, inclusive, were added by a single
hg pull, hg push or hg unbundle.
The source of these changes.
for details.
url: A URL.
location of the remote repository, if known.
for more information.
See also: incoming (), prechangegroup (), pretxnchangegroup ()
commit—after a new
changeset is createdThis hook is run after a new changeset has been created.
Parameters to this hook:
node: A changeset ID.
changeset ID of the newly committed changeset.
parent1: A changeset ID.
The changeset ID of the first parent of the newly
committed changeset.
parent2: A changeset ID.
The changeset ID of the second parent of the newly
committed changeset.
See also: precommit (), pretxncommit ()
incoming—after one
remote changeset is addedThis 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 (); it's simply more
convenient sometimes to run a hook once per group of
changesets, while other times it's handier once per changeset.
Parameters to this hook:
node: A changeset ID.
ID of the newly added changeset.
The source of these changes.
for details.
url: A URL.
location of the remote repository, if known.
for more information.
See also: changegroup () prechangegroup (), pretxnchangegroup ()
outgoing—after
changesets are propagatedThis 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.
Parameters to this hook:
node: A changeset ID.
changeset ID of the first changeset of the group that was
source: A string.
source of the of the operation (see ).
If a remote
client pulled changes from this repository,
source will be
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.
location of the remote repository, if known.
for more information.
See also: preoutgoing ()
prechangegroup—before starting
to add remote changesetsThis 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.
Parameters to this hook:
source: A string.
source of these changes.
for details.
url: A URL.
location of the remote repository, if known.
for more information.
See also: changegroup (), incoming (), pretxnchangegroup ()
precommit—before
starting to commit a changesetThis 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.
Parameters to this hook:
parent1: A changeset ID.
The changeset ID of the first parent of the working
directory.
parent2: A changeset ID.
The changeset ID of the second parent of the working
directory.
If the commit proceeds, the parents of the working
directory will become the parents of the new changeset.
See also: commit
(), pretxncommit ()
preoutgoing—before
starting to propagate changesetsThis 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.
Parameters to this hook:
The source of the operation that is attempting to
obtain changes from this repository (see ).
See the documentation
for the source parameter to the
outgoing hook, in
, for possible values
of this parameter.
url: A URL.
location of the remote repository, if known.
for more information.
See also: outgoing ()
This controlling hook is run before a tag is created.
the hook succeeds, creation of the tag proceeds.
If the hook
fails, the tag is not created.
Parameters to this hook:
local: A boolean.
the tag is local to this repository instance (i.e. stored
in .hg/localtags) or
managed by Mercurial (stored in .hgtags).
node: A changeset ID.
ID of the changeset to be tagged.
tag: A string.
The name of
the tag to be created.
If the tag to be created is
revision-controlled, the precommit and pretxncommit hooks ( and ) will also be run.
See also: tag
pretxnchangegroup—before
completing addition of remote changesetsThis controlling hook is run before a
transaction—that manages the addition of a group of new
changesets from outside the repository—completes.
the hook succeeds, the transaction completes, and all of the
changesets become permanent within this repository.
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 are permanent.
lead to race conditions if you do not take steps to avoid
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.
Parameters to this hook:
node: A changeset ID.
changeset ID of the first changeset in the group that was
All changesets between this and
inclusive, were added by a single hg pull, hg push or hg unbundle.
The source of these changes.
for details.
url: A URL.
location of the remote repository, if known.
for more information.
See also: changegroup (), incoming (), prechangegroup ()
pretxncommit—before
completing commit of new changesetThis 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.
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 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-new changeset as if it is permanent.
This may lead to
race conditions if you do not take steps to avoid them.
Parameters to this hook:node: A changeset ID.
changeset ID of the newly committed changeset.
parent1: A changeset ID.
The changeset ID of the first parent of the newly
committed changeset.
parent2: A changeset ID.
The changeset ID of the second parent of the newly
committed changeset.
See also: precommit ()
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
if it fails, the update or merge does not
Parameters to this hook:
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
The ID of the revision that the working directory
is being merged with.
See also: update
()This hook is run after a tag has been created.
Parameters to this hook:
local: A boolean.
the new tag is local to this repository instance (i.e.
stored in .hg/localtags) or managed by
Mercurial (stored in .hgtags).
node: A changeset ID.
ID of the changeset that was tagged.
tag: A string.
The name of
the tag that was created.
If the created tag is revision-controlled, the commit hook (section ) is run before this hook.
See also: pretag
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 revision that the working directory was merged with.
See also: preupdate