[PATCH] gnu: services: Add git-service.

[ng0 <ng0@we.make.ritual.n0.is>]

* gnu/services/version-control.scm: New file, create it.
(git-service): New Procedures.
(git-service-type): New variable.
* doc/guix.texi (Services)(Version Control): New section.
---
 doc/guix.texi                    |  38 ++++++++-
 gnu/local.mk                     |   1 +
 gnu/services/version-control.scm | 162 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 200 insertions(+), 1 deletion(-)
 create mode 100644 gnu/services/version-control.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index 7352ea9..fe53d08 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -7795,6 +7795,7 @@ declaration.
 * Web Services::                Web servers.
 * Network File System::         NFS related services.
 * Miscellaneous Services::      Other services.
+* Version Control::             Git and others.
 @end menu
 
 @node Base Services
@@ -11586,7 +11587,6 @@ If it is @code{#f} then the daemon will use the host's fully qualified domain na
 @node Miscellaneous Services
 @subsubsection Miscellaneous Services
 
-
 @cindex lirc
 @subsubheading Lirc Service
 
@@ -11673,6 +11673,42 @@ A @code{<dicod-database>} object serving the GNU Collaborative International
 Dictonary of English using the @code{gcide} package.
 @end defvr
 
+@node Version Control
+@subsubsection Version Control
+
+The @code{(gnu services version-control)} module provides the following services:
+
+@deffn {Scheme Procedure} git-service [#:git @var{git}] @
+       [#:base-directory "/var/git/repositories"] @
+       [#:user-directory? #f ""] [#:port 9418] @
+       [#:directory? #f ""] [#:max-connections 32] @
+       [#:pid-file? #t "/var/run/git-daemon.pid"]
+
+Return a service to run the @uref{https://git-scm.com, Git} daemon, a really simple
+TCP Git service which exposes local repositories for anonymous remote access.
+
+The git daemon runs as the @code{git} unprivileged user.  It is started with
+the fixed parameters @code{--syslog}, @code{--reuseaddr} and
+@code{"--no-informative-errors"}.
+You can pass the parameter @var{base-directory}, which remaps all the directory
+requests as relative to the given directory.  If you run git-service with
+@var{base-directory "/var/git/repositories"} on example.com, then if you later try
+to pull @code{git://example.com/hello.git}, git-service will interpret the directory
+as @code{/var/git/repositories/hello.git}.
+@var{max-connections} sets the maximum number of concurrent clients, it defaults to 32.
+Set it to 0 for no limit.
+@var{user-directory} allows allows ~user notation to be used in requests. When
+specified with no parameter, requests to @code{git://host/~alice/foo} is taken as a
+request to access @code{foo} repository in the home directory of user @code{alice}.
+If @var{user-directory "path"} is specified, the same request is taken as a request
+to access @code{path/foo} repository in the home directory of user @code{alice}.
+The parameter @var{directory "foo"} adds the directory "foo" and its subdirectories
+to the whitelist of allowed directories.
+Furthermore git-service takes the parameter @var{port}, which defaults to 9418.
+Run @command{man git daemon} for information about the options.
+
+@end deffn
+
 @node Setuid Programs
 @subsection Setuid Programs
 
diff --git a/gnu/local.mk b/gnu/local.mk
index 7112451..8769671 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -415,6 +415,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/services/sddm.scm				\
   %D%/services/spice.scm				\
   %D%/services/ssh.scm				\
+  %D%/services/version-control.scm              \
   %D%/services/web.scm				\
   %D%/services/xorg.scm				\
 						\
diff --git a/gnu/services/version-control.scm b/gnu/services/version-control.scm
new file mode 100644
index 0000000..8fa22a1
--- /dev/null
+++ b/gnu/services/version-control.scm
@@ -0,0 +1,162 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2016 ng0 <ng0@we.make.ritual.n0.is>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix 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 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix 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 GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu services version-control)
+  #:use-module (gnu services)
+  #:use-module (gnu services base)
+  #:use-module (gnu services shepherd)
+  #:use-module (gnu system shadow)
+  #:use-module (gnu packages version-control)
+  #:use-module (gnu packages admin)
+  #:use-module (guix records)
+  #:use-module (guix gexp)
+  #:use-module (srfi srfi-1)
+  #:use-module (ice-9 match)
+  #:export (git-service
+            git-service-type
+            git-configuration
+            git-configuration?
+            git-configuration-git
+            git-configuration-port
+            git-configuration-base-directory
+            git-configuration-pid-file
+            git-configuration-max-connections
+            git-configuration-user-directory
+            git-configuration-directory))
+
+;;; Commentary:
+;;;
+;;; Version Control related services.
+;;;
+;;; Code:
+
+\f
+;;;
+;;; git
+;;;
+
+(define-record-type* <git-configuration> git-configuration
+  make-git-configuration
+  git-configuration?
+  (git              git-configuration-git  ;package
+                    (default git))
+  (pid-file?        git-configuration-pid-file) ;string
+  (base-directory   git-configuration-base-directory) ;string
+  (user-directory?  git-configuration-user-directory) ;string
+  (directory?       git-configuration-directory) ;string
+  (max-connections  git-configuration-max-connections) ;number
+  (port             git-configuration-port)) ;number
+
+(define (git-shepherd-service config)
+  "Return a <shepherd-service> for git with CONFIG."
+  (define git (git-configuration-git config))
+
+  (define git-command
+    #~(list
+       (string-append #$git "/bin/git") "daemon" "--syslog" "--user=git"
+       "--group=git" "--no-informative-errors" "--reuseaddr"
+       ;; A directory to add to the whitelist of allowed directories. Unless
+       ;; --strict-paths is specified this will also include subdirectories of
+       ;; each named directory.
+       ;; --directory
+       ;; TODO: Add the option to add multiple occurences of --directory
+       (if (git-configuration-directory? config)
+           (string-append "--directory=" #$(git-configuration-directory config))
+           "")
+       ;; --interpolated-path=<pathtemplate>
+       ;; To support virtual hosting, an interpolated path template can be used to
+       ;; dynamically construct alternate paths. The template supports %H for the target
+       ;; hostname as supplied by the client but converted to all lowercase,
+       ;; %CH for the canonical hostname, %IP for the server’s IP address,
+       ;; %P for the port number, and %D for the absolute path of the named repository.
+       ;; After interpolation, the path is validated against the directory whitelist.
+
+       ;; --listen=<host_or_ipaddr>
+       ;; Listen on a specific IP address or hostname. IP addresses can be either an IPv4
+       ;; address or an IPv6 address if supported. If IPv6 is not supported, then
+       ;; --listen=hostname is also not supported and --listen must be given an IPv4 address.
+       ;; Can be given more than once. Incompatible with --inetd option.
+
+       ;; Maximum number of concurrent clients, defaults to 32. Set it to zero for no limit.
+       (string-append "--max-connections=" #$(number->string
+                                              (git-configuration-max-connections config)))
+
+       ;; --user-path, --user-path=<path>
+       ;; Allow ~user notation to be used in requests. When specified with no parameter,
+       ;; requests to git://host/~alice/foo is taken as a request to access foo repository
+       ;; in the home directory of user alice. If --user-path=path is specified, the same
+       ;; request is taken as a request to access path/foo repository in the home
+       ;; directory of user alice.
+       (if (git-configuration-user-directory? config)
+           "--user-path" "")
+
+       ;; Save the process id in file.
+       (if (git-configuration-pid-file? config)
+           (string-append "--pid-file=" #$(git-configuration-pid-file config))
+           "")
+       (string-append "--port=" #$(number->string (git-configuration-port config)))
+       (string-append "--base-path=" #$(git-configuration-base-directory config))))
+
+  (define requires '(networking syslogd))
+
+  (list (shepherd-service
+         (documentation "Git daemon server for git repositories")
+         (requirement requires)
+         (provision '(git))
+         (start #~(make-forkexec-constructor #$git-command))
+         (stop #~(make-kill-destructor)))))
+
+(define %git-accounts
+  ;; User account and groups for git-daemon.
+  (list (user-group
+         (name "git")
+         (system? #t))
+        (user-account
+         (name "git")
+         (system? #t)
+         (group "git")
+         (comment "Shepherd created user for the git-daemon service")
+         ;; (home-directory "/var/empty")
+         (home-directory "/var/git")
+         ;;(shell #~(string-append #$shadow "/sbin/nologin")))))
+         (shell #~(string-append #$shadow "/bin/git-shell")))))
+
+(define (git-activation config)
+  "Return the activation GEXP for CONFIG."
+  #~(begin
+      (use-modules (guix build utils))
+      (let ((user (getpwnam "git")))
+        (mkdir-p (dirname #$(git-configuration-pid-file config)))
+        (mkdir-p (dirname #$(git-configuration-base-directory config)))
+        (chown (dirname #$(git-configuration-base-directory config))
+               (passwd:uid user) (passwd:gid user)))))
+
+(define git-service-type
+  (service-type (name 'git)
+   (extensions
+    (list (service-extension shepherd-root-service-type
+                             git-shepherd-service)
+          (service-extension activation-service-type
+                             git-activation)))))
+
+(define* (git-service #:key (config (git-configuration)))
+  "Return a service that runs @url{https://git-scm.org,git} as a daemon.
+The daemon will listen on the port specified in @var{port}.
+In addition, @var{base-path} specifies the path which will repositories
+which can be exported by adding 'git-daemon-export-ok' files to them."
+  (service git-service-type config))
-- 
2.10.2