Using Pidgin Mercurial

The master copy of the source code for libpurple, Pidgin, Finch, ​http://pidgin.im/, and ​http://imfreedom.org/ resides in ​Mercurial repositories.

Background

Pidgin's Mercurial repositories are served by the ​mercurial-server package. This relies entirely upon SSH key-based authentication, providing access control and a layer of accountability.

Anonymous Pull (Non-Developers)

All Pidgin Mercurial repositories are available via HTTP from ​http://hg.pidgin.im.

Developers

Configure Mercurial

Mercurial uses an rc file to control its configuration. There are several that affect your use. One set of them is in /etc/mercurial and is controlled by your package manager. The others are entirely under your control. Each repository has its own hgrc file in repository/.hg/hgrc which can be used to configure Mercurial's behavior when interacting with that repository. Finally, there is ~/.hgrc, which affects Mercurial's behavior for any repository your user account touches.

When working with Pidgin's Mercurial repositories, we expect you to have at least a minimum configuration that gives your name in the 'First Last <email@…>' format. To do that, two simple lines need to be inserted into an appropriate hgrc (I believe most people will want to do this in ~/.hgrc):

[ui]
username = First Last <email@address.tld>

Other useful options that can be set in the [ui] section of an hgrc are the merge tool and to make Mercurial verbose or not:

[ui]
username = First Last <email@address.tld>
verbose = True
merge = meld

Git diffs can be useful too, and making hg log -v the default behavior for hg log can be helpful:

[diff]
git = 1

[defaults]
log = -v

Configure SSH For Access (Developers/CPW's/SoC Students Only)

If you wish, you can simplify Mercurial ssh: URL's by adding the following to ~/.ssh/config:

Host hg.pidgin.im
    Protocol 2
    User hg

SSH-based Push/Pull?

You can get your initial checkouts from Mercurial by:

• With SSH config above: hg clone ssh://hg.pidgin.im/path/to/repo
• Without SSH config above: hg clone ssh://hg@hg.pidgin.im/path/to/repo

Once initial clones are done, pulls are a simple matter of running hg pull within your working copy. You may optionally add -u to have your checkout automatically updated if possible.

Alternatively, you can clone the repository via http and add a default-push line to the [paths] section of the repository's .hg/hgrc file (you'll need to use the hg@ prefix if you haven't set it via the SSH config):

default-push = ssh://hg.pidgin.im/path/to/repo

Pushes are a simple matter of hg push within your working copy. If you need to push a new repository, you must clone:

• With SSH config above: hg clone . ssh://hg.pidgin.im/path/to/repo in working copy
• Without SSH config above: hg clone . ssh://hg@hg.pidgin.im/path/to/repo in working copy

Administration

Access Control

Access control on Pidgin's Mercurial server is strict. The repositories are structured like so (developers/CPW's listed here are for the purpose of example):

hg.pidgin.im          # Mercurial server
 + pidgin               # "Official" Pidgin and libpurple repositories
 |  + main                # replaced im.pidgin.pidgin in Monotone
 |  + 2_x_y               # replaced im.pidgin.pidgin.2.x.y in Monotone
 + dev                  # Developers' repositories
 |  + darkrain            # for all repositories darkrain wishes to create
 |  |  + irc                # replaced im.pidgin.cpw.darkrain42.irc in Monotone
 |  |  + xmpp_roster        # replaced im.pidgin.cpw.darkrain42.xppp.roster in Monotone
 |  + rekkanoryo          # for all repositories rekkanoryo wishes to create
 |     + examples           # replaced im.pidgin.cpw.rekkanoryo.examples in Monotone
 + cpw                  # Crazy Patch Writers' repositories
 |  + eionrobb            # for all repositories eionrobb wishes to create
 |     + newfeature          # new repository
 + www                  # For websites
 |  + pidgin              # for pidgin.im
 |  + imfreedom           # for imfreedom.org
 + soc                  # For Google Summer of Code projects (lines below should be obvious)
    + 2007
    |  + student1
    |     + project1
    + ...
    + 2012
       + studentx
          + projectx

Access control is as follows:

• Developers have write access to pidgin/*
• Developers can create and modify repositories in dev/$NICKNAME/
• Crazy Patch Writers can create and modify repositories in cpw/$NICKNAME/*
• Summer of Code students can create and modify repositories in soc/$YEAR/$NICKNAME/*
• All of the above have read access to any repository on the server.
• Those people with "root" access can do anything to any repository. This access is strictly controlled.

Adding New Users

The process to allow new users SSH access to the Mercurial repositories is pretty simple, but requires someone with "root" access to mercurial-server. Currently those people are datallah, rekkanoryo, and lschiere.

1. Check out the hgadmin repo: hg clone ssh://hg@hg.pidgin.im/hgadmin pidgin-hgadmin
2. cd pidgin-hgadmin/keys. Inhere is a series of directories. The format is self-explaining. Developers go in devs/$NICKNAME, CPW's in cpws/$NICKNAME, SoC students in soc/$NICKNAME. This is to allow a single developer, CPW, or SoC student to have multiple SSH keys, perhaps for multiple machines.
3. Create the appropriate directory.
4. Within this directory create a file named for the SSH key being added, for example user@somehost.
5. Put the SSH public key in this file.
6. hg add $FILE
7. Go back to the root of pidgin-hgadmin.
8. Edit access.conf. Copy an existing line for the same class of user (developer, CPW, SoC student) and modify it as appropriate for the new person's nickname and, if applicable, SoC year.
9. hg commit
10. hg push (mercurial-server updates automatically on push)

A Special Note About "root" Access

As indicated above, people who have "root" access to mercurial-server have the ability to configure the server via the hgadmin repo. They also have the ability to bypass all ACL's, and thus can write to any repository, including developers', CPWs', and SoC students' repositories.

Additionally, there is a safety net built into the mercurial-server configuration. In /etc/mercurial-server on rock.pidgin.im is a default ACL (access.conf) and a keys directory structure. This default ACL is what grants "root" users their privileges, and the keys directory structure contains two keys in the keys/root directory. These two keys belong to rekkanoryo and lschiere. These keys are located here in the server's filesystem instead of in the hgadmin repository as a safety net. When building the files used by mercurial-server, the tools always read from /etc/mercurial-server before reading from hgadmin; this allows rekkanoryo and lschiere to always be able to access the hgadmin repo in the event that it is damaged either through accidental or intentional means. This safety net means that at least two people will always have access to our repositories.

Hooks / Extensions

There are a number of hooks, extensions and other configuration in place for the various repositories:

Hooks

• ​pushlog.py tweaked version of a mozilla hook to keep track of who pushed a particular revision
  • This is registered globally as 'changelog.pushlog' for both the hg user and mercurial-server
• ​author_email_hook.py verify that incoming commit authors are in the form of an email address - 'user@domain.tld' or 'User Name <user@domain.tld>'
  • This is registered globally as 'pretxnchangegroup.authorcheck' for both the hg user and mercurial-server
• ​notify_repo_sync.sh trigger a sync in the background with the notification repo to trigger email and cia notifications
  • This is registered globally as 'changegroup.notify_sync' for both the hg user and mercurial-server
  • Note: an initial manual pull may be necessary for new repos
• ​notify.py slightly tweaked version of the built-in hg hook to facilitate using a separate repo for driving the notifications
  • This is registered in the /srv/mercurial-server/notification-repo/ (which isn't served anywhere)
• ​hgcia.py slightly tweaked version of the built-in hg hook for CIA bot notification
  • This is registered in the /srv/mercurial-server/notification-repo/ (which isn't served anywhere)

hgweb stuff

• ​pushlog extension extension to expose pushlog information gathered by the hook to hgweb
• ​hgweb templates slightly tweaked vanilla templates to add pushlog