[bug#27855] [PATCH] gnu: Add rsync service.

[Oleg Pykhalov]

* doc/guix.texi (Incremental file transfer): Add documentation.
* gnu/services/rsync.scm (<rsync-configuration>): New record type.
(rsync-accounts, rsync-shepherd-service): New service extensions.
(rsync-service-type): New service type.
---
 doc/guix.texi          |  58 ++++++++++++++++++
 gnu/local.mk           |   1 +
 gnu/services/rsync.scm | 162 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 221 insertions(+)
 create mode 100644 gnu/services/rsync.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index e8c4e0eaf..a3745ae01 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -15661,6 +15661,64 @@ Extra options will be passed to @code{git daemon}, 
please run
 @end table
 @end deftp
 
address@hidden Incremental file transfer
+
+The @code{(gnu services rsync)} module provides the following services:
+
address@hidden Rsync service
+
address@hidden {Scheme Variable} rsync-service-type
+This is the type for the @uref{https://rsync.samba.org} rsync daemon,
address@hidden record as in this example:
+
address@hidden
+(service rsync-service-type
+         (rsync-configuration))
address@hidden example
+
+See below for details about @code{rsync-configuration}.
address@hidden deffn
+
address@hidden {Data Type} rsync-configuration
+Data type representing the configuration for @code{rsync-service}.
+
address@hidden @asis
address@hidden @code{package} (default: @var{rsync})
+Package object of the Rsync utility for efficiently transferring and
+synchronizing files.
+
address@hidden @code{port-number} (default: @code{873})
+TCP port on which @command{rsync} listens for incoming connections.  If
+port is less than @code{1024} @command{rsync} will be started as the
address@hidden user and group.
+
address@hidden @code{pid-file} (default: @code{"/var/run/rsyncd.pid"})
+Name of the file where @command{rsync} writes its PID.
+
address@hidden @code{lock-file} (default: @code{"/var/run/rsyncd.lock"})
+Name of the file where @command{rsync} writes its lock file.
+
address@hidden @code{log-file} (default: @code{"/var/log/rsyncd.log"})
+Name of the file where @command{rsync} writes its log file.
+
address@hidden @code{use-choot?} (default: @var{#f})
+Whether to use chroot for @command{rsync} shared directory.
+
address@hidden @code{share-path} (default: @file{/srv/rsync})
+Location of the @command{rsync} shared directory.
+
address@hidden @code{share-comment} (default: @code{"Rsync share"})
+Comment of the @command{rsync} shared directory.
+
address@hidden @code{read-only?} (default: @var{#f})
+Read-write permissions to shared directory.
+
address@hidden @code{timeout} (default: @code{300})
+I/O timeout in seconds.
+
address@hidden table
address@hidden deftp
+
 @node Setuid Programs
 @subsection Setuid Programs
 
diff --git a/gnu/local.mk b/gnu/local.mk
index 724c6b675..fa514b278 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -444,6 +444,7 @@ GNU_SYSTEM_MODULES =                                \
   %D%/services/shepherd.scm                    \
   %D%/services/herd.scm                                \
   %D%/services/pm.scm                          \
+  %D%/services/rsync.scm                       \
   %D%/services/sddm.scm                                \
   %D%/services/spice.scm                               \
   %D%/services/ssh.scm                         \
diff --git a/gnu/services/rsync.scm b/gnu/services/rsync.scm
new file mode 100644
index 000000000..49c4cb7e2
--- /dev/null
+++ b/gnu/services/rsync.scm
@@ -0,0 +1,162 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Oleg Pykhalov <address@hidden>
+;;;
+;;; 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 rsync)
+  #:use-module (gnu services)
+  #:use-module (gnu services base)
+  #:use-module (gnu services shepherd)
+  #:use-module (gnu system shadow)
+  #:use-module (gnu packages rsync)
+  #:use-module (gnu packages admin)
+  #:use-module (guix records)
+  #:use-module (guix gexp)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 match)
+  #:export (rsync-configuration
+            rsync-configuration?
+            rsync-service-type))
+
+;;;
+;;; Rsync.
+;;;
+
+(define-record-type* <rsync-configuration>
+  rsync-configuration make-rsync-configuration
+  rsync-configuration?
+  ;; <package>
+  (package rsync-configuration-package
+           (default rsync))
+  ;; integer
+  (port-number rsync-configuration-port-number
+               (default 873))
+  ;; string
+  (pid-file rsync-configuration-pid-file
+            (default "/var/run/rsyncd.pid"))
+  ;; string
+  (lock-file rsync-configuration-lock-file
+             (default "/var/run/rsyncd.lock"))
+  ;; string
+  (log-file rsync-configuration-log-file
+            (default "/var/log/rsyncd.log"))
+  ;; Boolean
+  (use-chroot? rsync-configuration-use-chroot?
+               (default #f))
+  ;; string
+  (share-path rsync-configuration-share-path
+              (default "/srv/rsync"))
+  ;; string
+  (share-comment rsync-configuration-share-comment
+                 (default "Rsync share"))
+  ;; Boolean
+  (read-only? rsync-configuration-read-only?
+              (default #f))
+  ;; integer
+  (timeout rsync-configuration-timeout
+           (default 300)))
+
+(define %rsync-accounts
+  ;; User account and group for rsync.
+  (list (user-group (name "rsyncd") (system? #t))
+        (user-account
+         (name "rsyncd")
+         (system? #t)
+         (group "rsyncd")
+         (comment "rsyncd privilege separation user")
+         (home-directory "/var/run/rsyncd")
+         (shell #~(string-append #$shadow "/sbin/nologin")))))
+
+(define (rsync-activation config)
+  "Return the activation GEXP for CONFIG."
+  #~(begin
+      (use-modules (guix build utils))
+      (let ((share-directory #$(rsync-configuration-share-path config))
+            (user (getpw "rsyncd")))
+        (and=> share-directory mkdir-p)
+        (chown share-directory
+               (passwd:uid user)
+               (group:gid user)))))
+
+(define (rsync-config-file config)
+  "Return the rsync configuration file corresponding to CONFIG."
+  (computed-file
+   "rsync.conf"
+   #~(begin
+       (call-with-output-file #$output
+         (lambda (port)
+           (display "# Generated by 'rsync-service'.\n" port)
+           (format port "pid file = ~a\n"
+                   #$(rsync-configuration-pid-file config))
+           (format port "lock file = ~a\n"
+                   #$(rsync-configuration-lock-file config))
+           (format port "log file = ~a\n"
+                   #$(rsync-configuration-log-file config))
+           (format port "port = ~a\n"
+                   #$(number->string
+                      (rsync-configuration-port-number config)))
+           (format port "use chroot = ~a\n"
+                   #$(if (rsync-configuration-use-chroot? config)
+                         "true" "false"))
+           (display "[files]\n" port)
+           (format port "path = ~a\n"
+                   #$(rsync-configuration-share-path config))
+           (format port "comment = ~a\n"
+                   #$(rsync-configuration-share-comment config))
+           (format port "read only = ~a\n"
+                   #$(if (rsync-configuration-read-only? config)
+                         "true" "false"))
+           (format port "timeout = ~a\n"
+                   #$(number->string
+                      (rsync-configuration-timeout config)))
+           #t)))))
+
+(define (rsync-shepherd-service config)
+  "Return a <shepherd-service> for rsync with CONFIG."
+
+  (define rsync-command
+    #~(list (string-append #$(rsync-configuration-package config) "/bin/rsync")
+            "--daemon" "--config" #$(rsync-config-file config)))
+
+  (define pid-file
+    (rsync-configuration-pid-file config))
+
+  (define user
+    (let ((port (rsync-configuration-port-number config)))
+      (if (> port  1024)
+          "rsyncd"
+          "root")))
+
+  (list (shepherd-service
+         (provision '(rsync))
+         (documentation "Run rsync daemon.")
+         (start #~(make-forkexec-constructor #$rsync-command
+                                             #:pid-file #$pid-file
+                                             #:user #$user
+                                             #:group #$user))
+         (stop #~(make-kill-destructor)))))
+
+(define rsync-service-type
+  (service-type
+   (name 'rsync)
+   (extensions
+    (list (service-extension shepherd-root-service-type
+                             rsync-shepherd-service)
+          (service-extension account-service-type
+                             (const %rsync-accounts))
+          (service-extension activation-service-type
+                             rsync-activation)))))
-- 
2.13.3