path: root/Documentation/git-cvsserver.txt

git-cvsserver(1)
================

NAME
----
git-cvsserver - A CVS server emulator for git

SYNOPSIS
--------
[verse]
export CVS_SERVER=git-cvsserver
'cvs' -d :ext:user@server/path/repo.git co <HEAD_name>

DESCRIPTION
-----------

This application is a CVS emulation layer for git.

It is highly functional. However, not all methods are implemented,
and for those methods that are implemented,
not all switches are implemented.

Testing has been done using both the CLI CVS client, and the Eclipse CVS
plugin. Most functionality works fine with both of these clients.

LIMITATIONS
-----------

Currently cvsserver works over SSH connections for read/write clients, and
over pserver for anonymous CVS access.

CVS clients cannot tag, branch or perform GIT merges.

git-cvsserver maps GIT branches to CVS modules. This is very different
from what most CVS users would expect since in CVS modules usually represent
one or more directories.

INSTALLATION
------------

1. If you are going to offer anonymous CVS access via pserver, add a line in
   /etc/inetd.conf like
+
--
------
   cvspserver stream tcp nowait nobody git-cvsserver pserver

------
Note: In some cases, you need to pass the 'pserver' argument twice for
git-cvsserver to see it. So the line would look like

------
   cvspserver stream tcp nowait nobody git-cvsserver pserver pserver

------
No special setup is needed for SSH access, other than having GIT tools
in the PATH. If you have clients that do not accept the CVS_SERVER
env variable, you can rename git-cvsserver to cvs.
--
2. For each repo that you want accessible from CVS you need to edit config in
   the repo and add the following section.
+
--
------
   [gitcvs]
        enabled=1
        # optional for debugging
        logfile=/path/to/logfile

------
Note: you need to ensure each user that is going to invoke git-cvsserver has
write access to the log file and to the database (see
<<dbbackend,Database Backend>>. If you want to offer write access over
SSH, the users of course also need write access to the git repository itself.

[[configaccessmethod]]
All configuration variables can also be overriden for a specific method of
access. Valid method names are "ext" (for SSH access) and "pserver". The
following example configuration would disable pserver access while still
allowing access over SSH.
------
   [gitcvs]
        enabled=0

   [gitcvs "ext"]
        enabled=1
------
--
3. On the client machine you need to set the following variables.
   CVSROOT should be set as per normal, but the directory should point at the
   appropriate git repo. For example:
+
--
For SSH access, CVS_SERVER should be set to git-cvsserver

Example:

------
     export CVSROOT=:ext:user@server:/var/git/project.git
     export CVS_SERVER=git-cvsserver
------
--
4. For SSH clients that will make commits, make sure their .bashrc file
   sets the GIT_AUTHOR and GIT_COMMITTER variables.

5. Clients should now be able to check out the project. Use the CVS 'module'
   name to indicate what GIT 'head' you want to check out. Example:
+
------
     cvs co -d project-master master
------

[[dbbackend]]
Database Backend
----------------

git-cvsserver uses one database per git head (i.e. CVS module) to
store information about the repository for faster access. The
database doesn't contain any persitent data and can be completly
regenerated from the git repository at any time. The database
needs to be updated (i.e. written to) after every commit.

If the commit is done directly by using git (as opposed to
using git-cvsserver) the update will need to happen on the
next repository access by git-cvsserver, independent of
access method and requested operation.

That means that even if you offer only read access (e.g. by using
the pserver method), git-cvsserver should have write access to
the database to work reliably (otherwise you need to make sure
that the database if up-to-date all the time git-cvsserver is run).

By default it uses SQLite databases in the git directory, named
`gitcvs.<module_name>.sqlite`. Note that the SQLite backend creates
temporary files in the same directory as the database file on
write so it might not be enough to grant the users using
git-cvsserver write access to the database file without granting
them write access to the directory, too.

You can configure the database backend with the following
configuration variables:

Configuring database backend
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

git-cvsserver uses the Perl DBI module. Please also read
its documentation if changing these variables, especially
about `DBI->connect()`.

gitcvs.dbname::
	Database name. The exact meaning depends on the
	used database driver, for SQLite this is a filename.
	Supports variable substitution (see below). May
	not contain semicolons (`;`).
	Default: '%Ggitcvs.%m.sqlite'

gitcvs.dbdriver::
	Used DBI driver. You can specify any available driver
	for this here, but it might not work. cvsserver is tested
	with 'DBD::SQLite', reported to work with
	'DBD::Pg', and reported *not* to work with 'DBD::mysql'.
	Please regard this as an experimental feature. May not
	contain double colons (`:`).
	Default: 'SQLite'

gitcvs.dbuser::
	Database user. Only useful if setting `dbdriver`, since
	SQLite has no concept of database users. Supports variable
	substitution (see below).

gitcvs.dbpass::
	Database password.  Only useful if setting `dbdriver`, since
	SQLite has no concept of database passwords.

All variables can also be set per access method, see <<configaccessmethod,above>>.

Variable substitution
^^^^^^^^^^^^^^^^^^^^^
In `dbdriver` and `dbuser` you can use the following variables:

%G::
	git directory name
%g::
	git directory name, where all characters except for
	alpha-numeric ones, `.`, and `-` are replaced with
	`_` (this should make it easier to use the directory
	name in a filename if wanted)
%m::
	CVS module/git head name
%a::
	access method (one of "ext" or "pserver")
%u::
	Name of the user running git-cvsserver.
	If no name can be determined, the
	numeric uid is used.

Eclipse CVS Client Notes
------------------------

To get a checkout with the Eclipse CVS client:

1. Select "Create a new project -> From CVS checkout"
2. Create a new location. See the notes below for details on how to choose the
   right protocol.
3. Browse the 'modules' available. It will give you a list of the heads in
   the repository. You will not be able to browse the tree from there. Only
   the heads.
4. Pick 'HEAD' when it asks what branch/tag to check out. Untick the
   "launch commit wizard" to avoid committing the .project file.

Protocol notes: If you are using anonymous access via pserver, just select that.
Those using SSH access should choose the 'ext' protocol, and configure 'ext'
access on the Preferences->Team->CVS->ExtConnection pane. Set CVS_SERVER to
'git-cvsserver'. Note that password support is not good when using 'ext',
you will definitely want to have SSH keys setup.

Alternatively, you can just use the non-standard extssh protocol that Eclipse
offer. In that case CVS_SERVER is ignored, and you will have to replace
the cvs utility on the server with git-cvsserver or manipulate your `.bashrc`
so that calling 'cvs' effectively calls git-cvsserver.

Clients known to work
---------------------

- CVS 1.12.9 on Debian
- CVS 1.11.17 on MacOSX (from Fink package)
- Eclipse 3.0, 3.1.2 on MacOSX (see Eclipse CVS Client Notes)
- TortoiseCVS

Operations supported
--------------------

All the operations required for normal use are supported, including
checkout, diff, status, update, log, add, remove, commit.
Legacy monitoring operations are not supported (edit, watch and related).
Exports and tagging (tags and branches) are not supported at this stage.

The server should set the '-k' mode to binary when relevant, however,
this is not really implemented yet. For now, you can force the server
to set '-kb' for all files by setting the `gitcvs.allbinary` config
variable. In proper GIT tradition, the contents of the files are
always respected. No keyword expansion or newline munging is supported.

Dependencies
------------

git-cvsserver depends on DBD::SQLite.

Copyright and Authors
---------------------

This program is copyright The Open University UK - 2006.

Authors:

- Martyn Smith    <martyn@catalyst.net.nz>
- Martin Langhoff <martin@catalyst.net.nz>

with ideas and patches from participants of the git-list <git@vger.kernel.org>.

Documentation
--------------
Documentation by Martyn Smith <martyn@catalyst.net.nz>, Martin Langhoff <martin@catalyst.net.nz>, and Matthias Urlichs <smurf@smurf.noris.de>.

GIT
---
Part of the gitlink:git[7] suite