git-http-backend - Online in the Cloud

PROGRAM:

NAME

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

SYNOPSIS

git http-backend

DESCRIPTION

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.

SERVICES

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.

URL TRANSLATION

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.

EXAMPLES

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
for both the initial ref advertisement (which we detect as a push via the service
parameter in the query string), and the receive-pack invocation itself:

RewriteCond %{QUERY_STRING} service=git-receive-pack [OR]
RewriteCond %{REQUEST_URI} /git-receive-pack$
RewriteRule ^/git/ - [E=AUTHREQUIRED:yes]

<LocationMatch "^/git/">
Order Deny,Allow
Deny from env=AUTHREQUIRED

AuthType Basic
AuthName "Git Access"
Require group committers
Satisfy Any
...
</LocationMatch>

If you do not have mod_rewrite available to match against the query string, it is
sufficient to just protect git-receive-pack itself, like:

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

In this mode, the server will not request authentication until the client actually
starts the object negotiation phase of the push, rather than during the initial
contact. For this reason, you must also enable the http.receivepack config option in
any repositories that should accept a push. The default behavior, if http.receivepack
is not set, is to reject any pushes by unauthenticated users; the initial request will
therefore report 403 Forbidden to the client, without even giving an opportunity for
authentication.

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/

To serve multiple repositories from different gitnamespaces(7) in a single repository:

SetEnvIf Request_URI "^/git/([^/]*)" GIT_NAMESPACE=$1
ScriptAliasMatch ^/git/[^/]*(.*) /usr/libexec/git-core/git-http-backend/storage.git$1

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/

Lighttpd
Ensure that mod_cgi, mod_alias, mod_auth, mod_setenv are loaded, then set
GIT_PROJECT_ROOT appropriately and redirect all requests to the CGI:

alias.url += ( "/git" => "/usr/lib/git-core/git-http-backend" )
$HTTP["url"] =~ "^/git" {
cgi.assign = ("" => "")
setenv.add-environment = (
"GIT_PROJECT_ROOT" => "/var/www/git",
"GIT_HTTP_EXPORT_ALL" => ""
)
}

To enable anonymous read access but authenticated write access:

$HTTP["querystring"] =~ "service=git-receive-pack" {
include "git-auth.conf"
}
$HTTP["url"] =~ "^/git/.*/git-receive-pack$" {
include "git-auth.conf"
}

where git-auth.conf looks something like:

auth.require = (
"/" => (
"method" => "basic",
"realm" => "Git Access",
"require" => "valid-user"
)
)
# ...and set up auth.backend here

To require authentication for both reads and writes:

$HTTP["url"] =~ "^/git/private" {
include "git-auth.conf"
}

ENVIRONMENT

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 GIT_HTTP_MAX_REQUEST_BUFFER environment variable (or the http.maxRequestBuffer config
variable) may be set to change the largest ref negotiation request that git will handle
during a fetch; any fetch requiring a larger buffer will not succeed. This value should
not normally need to be changed, but may be helpful if you are fetching from a repository
with an extremely large number of refs. The value can be specified with a unit (e.g., 100M
for 100 megabytes). The default is 10 megabytes.

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.

GIT

Part of the git(1) suite

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