mercurial-server

mercurial-server makes a group of repositories available to the developers
you choose, identified by ssh keys, with easy key and access management
based on hg.

http://hg.opensource.lshift.net/mercurial-server/

Copyright (C) 2008-2009 LShift Ltd.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

SUMMARY

mercurial-server makes a group of repositories available to the developers
you choose, identified by ssh keys, with easy key and access management
based on hg.

All of the repositories controlled by mercurial-server are owned by a
single user (the "hg" user in what follows), but many remote users can act
on them, and different users can have different permissions. We don't use
file permissions to achieve that - instead, developers log in as the "hg"
user when they connect to the repository host using ssh, using ssh URLs of
the form "ssh://hg@repository-host/repository-name". A restricted shell
prevents them from using this access for unauthorized purposes. Developers
are authenticated only using SSH keys; no other form of authentication is
supported. 

To give a user access to the repository, place their key in an
appropriately-named subdirectory of "/etc/mercurial-server/keys" and run
"/usr/local/lib/mercurial-server/refresh-auth". You can then control what
access they have to what repositories by editing the control file
"/etc/mercurial-server/access.conf", which can match the names of these keys
against a glob pattern. 

For convenient remote control of access, you can instead (if you have the
privileges) make changes to a special repository called "hgadmin", which
contains its own "access.conf" file and "keys" directory. Changes pushed to
this repository take effect immediately. The two "access.conf" files are
concatenated, and the keys directories merged.

QUICK START

You and all developers using this system will need an SSH public key, and
will almost certainly want to be running ssh-agent (or its equivalent, eg
Pageant under Windows). If you're not familiar with ssh-agent, you should
learn about that before using this.

In what follows, certain operations (eg installing mercurial-server itself)
have to be done on the repository server (which we call "repository-host"),
but any operation that involves checking in or out of Mercurial can be done
wherever is most convenient to you; the most usual arrangment would be that
you'd do these things at the machine you sit at, and on which you run
ssh-agent, which is what authenticates you when you talk to the repository
server.

Ensure there is no user called "hg" on the repository host, and run
"./install". This installs the mercurial-server files and control files, and
creates and sets up the "hg" user.

Place your SSH public key in the directory "/etc/mercurial-server/keys/root".
I suggest creating yourself a directory and naming the key after your hostname
(ie the file is called something like
"/etc/mercurial-server/keys/root/yourname/yourhostname") so that you can
easily manage users who have a different key on each host they use. Then run
"/usr/local/lib/mercurial-server/refresh-auth".

The repository is now ready to use, and you are now the sole user able to
change and create repositories on this repository host.  

CREATING REPOSITORIES

To create a new repository, you clone a local repository onto the remote
server. So if you want a new empty repository called "myproject", you can do
(as yourself):

    hg init myproject
    hg clone myproject ssh://hg@repository-host/myproject

ADDING OTHER USERS

Because your key is in the "keys/root" subdirectory, you have the equivalent
of "root privileges" over mercurial-server (not the whole computer, just
mercurial-server). You can add other root users by putting their keys next to
yours, or you can make less privileged users by putting their keys in the
"keys/users" subdirectory - these users will be able to read and write to any
repository (except one - see below) but will not be able to create new
repositories. As always, when you change "/etc/mercurial-server/keys" you need
to re-run "/usr/local/lib/mercurial-server/refresh-auth".

LOGGING

Every push and pull is logged with the key used: see the file .hg/serve-log in
each repository.

USING HGADMIN

It can be inconvenient to log on to the repository server, become root, copy
keys around, and run "refresh-auth" every time you want to change user
privileges. This is where mercurial-server shines :-) Suppose you have another
user's SSH public key in the file "/tmp/theirkey" (on the machine you sit at,
not necessarily the repository server) and you want to give them user-level
access to the repository server. Run these commands:

    hg clone ssh://hg@repository-server/hgadmin
    cd hgadmin
    mkdir keys/users/thatuser
    cp /tmp/theirkey keys/users/thatuser/theirhostname
    hg add
    hg commit -m "Added key for thatuser"
    hg push

In other words, hgadmin is a version controlled version of
"/etc/mercurial-server", and changes to it take effect immediately -
"refresh-auth" is run after every push. 

With the default access.conf file (see doc/configuring-access for more
details) only users in "keys/root" can act on "hgadmin" - those with keys in
"keys/users" cannot even read this repository. So multiple admins can use
Mercurial's version control to cooperate on controlling access to the
repository server in a natural way.

You can also create an "access.conf" file in hgadmin, and this is appended to
/etc/mercurial-server/access.conf whenever this is read - in other words,
rules in the latter take precedence over those in the former. So once you're
working with "hgadmin", it can be convenient to remove all the keys in
"/etc/mercurial-server/keys" and all the entries in
"/etc/mercurial-server/access.conf" and use hgadmin to control everything. If
you find yourself locked out, you can get back in again by restoring some of
the entries you removed from these files.

MORE INFORMATION

For more on how to use mercurial-server and configure access, see the files in
the doc directory.

THANKS

Thanks for reading this far. If you use mercurial-server, please tell me about
it.

Paul Crowley, 2009