777e75b605
Communication between the HTTP server and http_backend process can lead to a dead-lock when relaying a large ref negotiation request. Diagnose the situation better, and mitigate it by reading such a request first into core (to a reasonable limit). * jk/http-backend-deadlock: http-backend: spool ref negotiation requests to buffer t5551: factor out tag creation http-backend: fix die recursion with custom handler
278 lines
9.8 KiB
Plaintext
278 lines
9.8 KiB
Plaintext
git-http-backend(1)
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===================
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NAME
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----
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git-http-backend - Server side implementation of Git over HTTP
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SYNOPSIS
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--------
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[verse]
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'git http-backend'
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DESCRIPTION
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-----------
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A simple CGI program to serve the contents of a Git repository to Git
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clients accessing the repository over http:// and https:// protocols.
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The program supports clients fetching using both the smart HTTP protocol
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and the backwards-compatible dumb HTTP protocol, as well as clients
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pushing using the smart HTTP protocol.
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It verifies that the directory has the magic file
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"git-daemon-export-ok", and it will refuse to export any Git directory
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that hasn't explicitly been marked for export this way (unless the
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GIT_HTTP_EXPORT_ALL environmental variable is set).
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By default, only the `upload-pack` service is enabled, which serves
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'git fetch-pack' and 'git ls-remote' clients, which are invoked from
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'git fetch', 'git pull', and 'git clone'. If the client is authenticated,
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the `receive-pack` service is enabled, which serves 'git send-pack'
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clients, which is invoked from 'git push'.
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SERVICES
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--------
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These services can be enabled/disabled using the per-repository
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configuration file:
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http.getanyfile::
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This serves Git clients older than version 1.6.6 that are unable to use the
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upload pack service. When enabled, clients are able to read
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any file within the repository, including objects that are
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no longer reachable from a branch but are still present.
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It is enabled by default, but a repository can disable it
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by setting this configuration item to `false`.
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http.uploadpack::
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This serves 'git fetch-pack' and 'git ls-remote' clients.
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It is enabled by default, but a repository can disable it
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by setting this configuration item to `false`.
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http.receivepack::
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This serves 'git send-pack' clients, allowing push. It is
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disabled by default for anonymous users, and enabled by
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default for users authenticated by the web server. It can be
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disabled by setting this item to `false`, or enabled for all
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users, including anonymous users, by setting it to `true`.
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URL TRANSLATION
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---------------
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To determine the location of the repository on disk, 'git http-backend'
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concatenates the environment variables PATH_INFO, which is set
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automatically by the web server, and GIT_PROJECT_ROOT, which must be set
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manually in the web server configuration. If GIT_PROJECT_ROOT is not
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set, 'git http-backend' reads PATH_TRANSLATED, which is also set
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automatically by the web server.
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EXAMPLES
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--------
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All of the following examples map `http://$hostname/git/foo/bar.git`
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to `/var/www/git/foo/bar.git`.
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Apache 2.x::
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Ensure mod_cgi, mod_alias, and mod_env are enabled, set
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GIT_PROJECT_ROOT (or DocumentRoot) appropriately, and
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create a ScriptAlias to the CGI:
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+
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----------------------------------------------------------------
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SetEnv GIT_PROJECT_ROOT /var/www/git
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SetEnv GIT_HTTP_EXPORT_ALL
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ScriptAlias /git/ /usr/libexec/git-core/git-http-backend/
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----------------------------------------------------------------
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+
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To enable anonymous read access but authenticated write access,
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require authorization for both the initial ref advertisement (which we
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detect as a push via the service parameter in the query string), and the
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receive-pack invocation itself:
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+
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----------------------------------------------------------------
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RewriteCond %{QUERY_STRING} service=git-receive-pack [OR]
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RewriteCond %{REQUEST_URI} /git-receive-pack$
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RewriteRule ^/git/ - [E=AUTHREQUIRED:yes]
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<LocationMatch "^/git/">
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Order Deny,Allow
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Deny from env=AUTHREQUIRED
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AuthType Basic
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AuthName "Git Access"
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Require group committers
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Satisfy Any
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...
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</LocationMatch>
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----------------------------------------------------------------
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+
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If you do not have `mod_rewrite` available to match against the query
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string, it is sufficient to just protect `git-receive-pack` itself,
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like:
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+
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----------------------------------------------------------------
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<LocationMatch "^/git/.*/git-receive-pack$">
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AuthType Basic
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AuthName "Git Access"
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Require group committers
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...
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</LocationMatch>
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----------------------------------------------------------------
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+
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In this mode, the server will not request authentication until the
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client actually starts the object negotiation phase of the push, rather
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than during the initial contact. For this reason, you must also enable
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the `http.receivepack` config option in any repositories that should
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accept a push. The default behavior, if `http.receivepack` is not set,
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is to reject any pushes by unauthenticated users; the initial request
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will therefore report `403 Forbidden` to the client, without even giving
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an opportunity for authentication.
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+
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To require authentication for both reads and writes, use a Location
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directive around the repository, or one of its parent directories:
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+
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----------------------------------------------------------------
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<Location /git/private>
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AuthType Basic
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AuthName "Private Git Access"
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Require group committers
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...
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</Location>
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----------------------------------------------------------------
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+
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To serve gitweb at the same url, use a ScriptAliasMatch to only
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those URLs that 'git http-backend' can handle, and forward the
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rest to gitweb:
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+
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----------------------------------------------------------------
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ScriptAliasMatch \
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"(?x)^/git/(.*/(HEAD | \
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info/refs | \
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objects/(info/[^/]+ | \
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[0-9a-f]{2}/[0-9a-f]{38} | \
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pack/pack-[0-9a-f]{40}\.(pack|idx)) | \
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git-(upload|receive)-pack))$" \
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/usr/libexec/git-core/git-http-backend/$1
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ScriptAlias /git/ /var/www/cgi-bin/gitweb.cgi/
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----------------------------------------------------------------
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+
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To serve multiple repositories from different linkgit:gitnamespaces[7] in a
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single repository:
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----------------------------------------------------------------
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SetEnvIf Request_URI "^/git/([^/]*)" GIT_NAMESPACE=$1
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ScriptAliasMatch ^/git/[^/]*(.*) /usr/libexec/git-core/git-http-backend/storage.git$1
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----------------------------------------------------------------
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Accelerated static Apache 2.x::
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Similar to the above, but Apache can be used to return static
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files that are stored on disk. On many systems this may
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be more efficient as Apache can ask the kernel to copy the
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file contents from the file system directly to the network:
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----------------------------------------------------------------
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SetEnv GIT_PROJECT_ROOT /var/www/git
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AliasMatch ^/git/(.*/objects/[0-9a-f]{2}/[0-9a-f]{38})$ /var/www/git/$1
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AliasMatch ^/git/(.*/objects/pack/pack-[0-9a-f]{40}.(pack|idx))$ /var/www/git/$1
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ScriptAlias /git/ /usr/libexec/git-core/git-http-backend/
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----------------------------------------------------------------
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This can be combined with the gitweb configuration:
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+
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----------------------------------------------------------------
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SetEnv GIT_PROJECT_ROOT /var/www/git
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AliasMatch ^/git/(.*/objects/[0-9a-f]{2}/[0-9a-f]{38})$ /var/www/git/$1
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AliasMatch ^/git/(.*/objects/pack/pack-[0-9a-f]{40}.(pack|idx))$ /var/www/git/$1
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ScriptAliasMatch \
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"(?x)^/git/(.*/(HEAD | \
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info/refs | \
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objects/info/[^/]+ | \
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git-(upload|receive)-pack))$" \
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/usr/libexec/git-core/git-http-backend/$1
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ScriptAlias /git/ /var/www/cgi-bin/gitweb.cgi/
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----------------------------------------------------------------
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Lighttpd::
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Ensure that `mod_cgi`, `mod_alias`, `mod_auth`, `mod_setenv` are
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loaded, then set `GIT_PROJECT_ROOT` appropriately and redirect
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all requests to the CGI:
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+
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----------------------------------------------------------------
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alias.url += ( "/git" => "/usr/lib/git-core/git-http-backend" )
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$HTTP["url"] =~ "^/git" {
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cgi.assign = ("" => "")
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setenv.add-environment = (
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"GIT_PROJECT_ROOT" => "/var/www/git",
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"GIT_HTTP_EXPORT_ALL" => ""
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)
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}
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----------------------------------------------------------------
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To enable anonymous read access but authenticated write access:
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----------------------------------------------------------------
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$HTTP["querystring"] =~ "service=git-receive-pack" {
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include "git-auth.conf"
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}
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$HTTP["url"] =~ "^/git/.*/git-receive-pack$" {
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include "git-auth.conf"
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}
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----------------------------------------------------------------
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where `git-auth.conf` looks something like:
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----------------------------------------------------------------
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auth.require = (
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"/" => (
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"method" => "basic",
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"realm" => "Git Access",
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"require" => "valid-user"
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)
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)
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# ...and set up auth.backend here
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----------------------------------------------------------------
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To require authentication for both reads and writes:
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----------------------------------------------------------------
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$HTTP["url"] =~ "^/git/private" {
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include "git-auth.conf"
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}
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----------------------------------------------------------------
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ENVIRONMENT
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-----------
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'git http-backend' relies upon the CGI environment variables set
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by the invoking web server, including:
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* PATH_INFO (if GIT_PROJECT_ROOT is set, otherwise PATH_TRANSLATED)
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* REMOTE_USER
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* REMOTE_ADDR
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* CONTENT_TYPE
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* QUERY_STRING
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* REQUEST_METHOD
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The GIT_HTTP_EXPORT_ALL environmental variable may be passed to
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'git-http-backend' to bypass the check for the "git-daemon-export-ok"
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file in each repository before allowing export of that repository.
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The `GIT_HTTP_MAX_REQUEST_BUFFER` environment variable (or the
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`http.maxRequestBuffer` config variable) may be set to change the
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largest ref negotiation request that git will handle during a fetch; any
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fetch requiring a larger buffer will not succeed. This value should not
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normally need to be changed, but may be helpful if you are fetching from
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a repository with an extremely large number of refs. The value can be
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specified with a unit (e.g., `100M` for 100 megabytes). The default is
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10 megabytes.
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The backend process sets GIT_COMMITTER_NAME to '$REMOTE_USER' and
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GIT_COMMITTER_EMAIL to '$\{REMOTE_USER}@http.$\{REMOTE_ADDR\}',
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ensuring that any reflogs created by 'git-receive-pack' contain some
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identifying information of the remote user who performed the push.
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All CGI environment variables are available to each of the hooks
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invoked by the 'git-receive-pack'.
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GIT
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---
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Part of the linkgit:git[1] suite
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