GIT−HTTP−BACKEND

git-http-backend − Server side implementation of Git over HTTP

git http−backend

A simple CGI program to serve the contents of a Git repository to Git clients accessing the repository over http:// and https:// protocols. The program supports clients fetching using both the smart HTTP protocol and the backwards−compatible dumb HTTP protocol, as well as clients pushing using the smart HTTP protocol.

It verifies that the directory has the magic file "git−daemon−export−ok", and it will refuse to export any git directory that hasn’t explicitly been marked for export this way (unless the GIT_HTTP_EXPORT_ALL environmental variable is set).

By default, only the upload−pack service is enabled, which serves git fetch−pack and git ls−remote clients, which are invoked from git fetch, git pull, and git clone. If the client is authenticated, the receive−pack service is enabled, which serves git send−pack clients, which is invoked from git push.

These services can be enabled/disabled using the per−repository configuration file:

http.getanyfile

This serves Git clients older than version 1.6.6 that are unable to use the upload pack service. When enabled, clients are able to read any file within the repository, including objects that are no longer reachable from a branch but are still present. It is enabled by default, but a repository can disable it by setting this configuration item to false.

http.uploadpack

This serves git fetch−pack and git ls−remote clients. It is enabled by default, but a repository can disable it by setting this configuration item to false.

http.receivepack

This serves git send−pack clients, allowing push. It is disabled by default for anonymous users, and enabled by default for users authenticated by the web server. It can be disabled by setting this item to false, or enabled for all users, including anonymous users, by setting it to true.

To determine the location of the repository on disk, git http−backend concatenates the environment variables PATH_INFO, which is set automatically by the web server, and GIT_PROJECT_ROOT, which must be set manually in the web server configuration. If GIT_PROJECT_ROOT is not set, git http−backend reads PATH_TRANSLATED, which is also set automatically by the web server.

All of the following examples map http://$hostname/git/foo/bar.git to /var/www/git/foo/bar.git.

Apache 2.x

Ensure mod_cgi, mod_alias, and mod_env are enabled, set GIT_PROJECT_ROOT (or DocumentRoot) appropriately, and create a ScriptAlias to the CGI:

SetEnv GIT_PROJECT_ROOT /var/www/git
SetEnv GIT_HTTP_EXPORT_ALL
ScriptAlias /git/ /usr/libexec/git−core/git−http−backend/

To enable anonymous read access but authenticated write access, require authorization with a LocationMatch directive:

<LocationMatch "^/git/.*/git−receive−pack$">
        AuthType Basic
        AuthName "Git Access"
        Require group committers
        ...
</LocationMatch>

To require authentication for both reads and writes, use a Location directive around the repository, or one of its parent directories:

<Location /git/private>
        AuthType Basic
        AuthName "Private Git Access"
        Require group committers
        ...
</Location>

To serve gitweb at the same url, use a ScriptAliasMatch to only those URLs that git http−backend can handle, and forward the rest to gitweb:

ScriptAliasMatch \
        "(?x)^/git/(.*/(HEAD | \
                        info/refs | \
                        objects/(info/[^/]+ | \
                                 [0−9a−f]{2}/[0−9a−f]{38} | \
                                 pack/pack−[0−9a−f]{40}\.(pack|idx)) | \
                        git−(upload|receive)−pack))$" \
        /usr/libexec/git−core/git−http−backend/$1

ScriptAlias /git/ /var/www/cgi−bin/gitweb.cgi/

Accelerated static Apache 2.x

Similar to the above, but Apache can be used to return static files that are stored on disk. On many systems this may be more efficient as Apache can ask the kernel to copy the file contents from the file system directly to the network:

SetEnv GIT_PROJECT_ROOT /var/www/git

AliasMatch ^/git/(.*/objects/[0−9a−f]{2}/[0−9a−f]{38})$          /var/www/git/$1
AliasMatch ^/git/(.*/objects/pack/pack−[0−9a−f]{40}.(pack|idx))$ /var/www/git/$1
ScriptAlias /git/ /usr/libexec/git−core/git−http−backend/

This can be combined with the gitweb configuration:

SetEnv GIT_PROJECT_ROOT /var/www/git

AliasMatch ^/git/(.*/objects/[0−9a−f]{2}/[0−9a−f]{38})$          /var/www/git/$1
AliasMatch ^/git/(.*/objects/pack/pack−[0−9a−f]{40}.(pack|idx))$ /var/www/git/$1
ScriptAliasMatch \
        "(?x)^/git/(.*/(HEAD | \
                        info/refs | \
                        objects/info/[^/]+ | \
                        git−(upload|receive)−pack))$" \
        /usr/libexec/git−core/git−http−backend/$1
ScriptAlias /git/ /var/www/cgi−bin/gitweb.cgi/

git http−backend relies upon the CGI environment variables set by the invoking web server, including:

• PATH_INFO (if GIT_PROJECT_ROOT is set, otherwise PATH_TRANSLATED)

• REMOTE_USER

• REMOTE_ADDR

• CONTENT_TYPE

• QUERY_STRING

• REQUEST_METHOD

The GIT_HTTP_EXPORT_ALL environmental variable may be passed to git−http−backend to bypass the check for the "git−daemon−export−ok" file in each repository before allowing export of that repository.

The backend process sets GIT_COMMITTER_NAME to $REMOTE_USER and GIT_COMMITTER_EMAIL to ${REMOTE_USER}@http.${REMOTE_ADDR}, ensuring that any reflogs created by git−receive−pack contain some identifying information of the remote user who performed the push.

All CGI environment variables are available to each of the hooks invoked by the git−receive−pack.

Written by Shawn O. Pearce <spearce@spearce.org [1] >.

Documentation by Shawn O. Pearce <spearce@spearce.org [1] >.

Part of the git(1) suite

1.

spearce@spearce.org

mailto:spearce@spearce.org