gnu: Add rsync service.

* doc/guix.texi (Networking Services): Add rsync service documentation.
* gnu/services/rsync.scm (<rsync-configuration>): New file.
* gnu/tests/rsync.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add new files.

Signed-off-by: Christopher Baines <mail@cbaines.net>

doc/guix.texi

@@ -10335,6 +10335,75 @@ In addition, @var{extra-settings} specifies a string to append to the
 configuration file.
 @end deffn
 
+The @code{(gnu services rsync)} module provides the following services:
+
+You might want an rsync daemon if you have files that you want available
+so anyone (or just yourself) can download existing files or upload new
+files.
+
+@deffn {Scheme Variable} rsync-service-type
+This is the type for the @uref{https://rsync.samba.org, rsync} rsync daemon,
+@command{rsync-configuration} record as in this example:
+
+@example
+(service rsync-service-type)
+@end example
+
+See below for details about @code{rsync-configuration}.
+@end deffn
+
+@deftp {Data Type} rsync-configuration
+Data type representing the configuration for @code{rsync-service}.
+
+@table @asis
+@item @code{package} (default: @var{rsync})
+@code{rsync} package to use.
+
+@item @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} needs to be started as the
+@code{root} user and group.
+
+@item @code{pid-file} (default: @code{"/var/run/rsyncd/rsyncd.pid"})
+Name of the file where @command{rsync} writes its PID.
+
+@item @code{lock-file} (default: @code{"/var/run/rsyncd/rsyncd.lock"})
+Name of the file where @command{rsync} writes its lock file.
+
+@item @code{log-file} (default: @code{"/var/log/rsyncd.log"})
+Name of the file where @command{rsync} writes its log file.
+
+@item @code{use-chroot?} (default: @var{#t})
+Whether to use chroot for @command{rsync} shared directory.
+
+@item @code{share-path} (default: @file{/srv/rsync})
+Location of the @command{rsync} shared directory.
+
+@item @code{share-comment} (default: @code{"Rsync share"})
+Comment of the @command{rsync} shared directory.
+
+@item @code{read-only?} (default: @var{#f})
+Read-write permissions to shared directory.
+
+@item @code{timeout} (default: @code{300})
+I/O timeout in seconds.
+
+@item @code{user} (default: @var{"root"})
+Owner of the @code{rsync} process.
+
+@item @code{group} (default: @var{"root"})
+Group of the @code{rsync} process.
+
+@item @code{uid} (default: @var{"rsyncd"})
+User name or user ID that file transfers to and from that module should take
+place as when the daemon was run as @code{root}.
+
+@item @code{gid} (default: @var{"rsyncd"})
+Group name or group ID that will be used when accessing the module.
+
+@end table
+@end deftp
+
 Furthermore, @code{(gnu services ssh)} provides the following services.
 @cindex SSH
 @cindex SSH server

gnu/local.mk

@@ -452,6 +452,7 @@ 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				\
@@ -498,6 +499,7 @@ GNU_SYSTEM_MODULES =				\
   %D%/tests/mail.scm				\
   %D%/tests/messaging.scm			\
   %D%/tests/networking.scm			\
+  %D%/tests/rsync.scm				\
   %D%/tests/ssh.scm				\
   %D%/tests/virtualization.scm			\
   %D%/tests/web.scm

gnu/services/rsync.scm

@@ -0,0 +1,172 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Oleg Pykhalov <go.wigust@gmail.com>
+;;;
+;;; 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))
+
+;;;; Commentary:
+;;;
+;;; This module implements a service that to run instance of Rsync,
+;;; files synchronization tool.
+;;;
+;;;; Code:
+
+(define-record-type* <rsync-configuration>
+  rsync-configuration
+  make-rsync-configuration
+  rsync-configuration?
+  (package       rsync-configuration-package              ; package
+                 (default rsync))
+  (port-number   rsync-configuration-port-number          ; integer
+                 (default 873))
+  (pid-file      rsync-configuration-pid-file             ; string
+                 (default "/var/run/rsyncd/rsyncd.pid"))
+  (lock-file     rsync-configuration-lock-file            ; string
+                 (default "/var/run/rsyncd/rsyncd.lock"))
+  (log-file      rsync-configuration-log-file             ; string
+                 (default "/var/log/rsyncd.log"))
+  (use-chroot?   rsync-configuration-use-chroot?          ; boolean
+                 (default #t))
+  (share-path    rsync-configuration-share-path           ; string
+                 (default "/srv/rsyncd"))
+  (share-comment rsync-configuration-share-comment        ; string
+                 (default "Rsync share"))
+  (read-only?    rsync-configuration-read-only?           ; boolean
+                 (default #f))
+  (timeout       rsync-configuration-timeout              ; integer
+                 (default 300))
+  (user          rsync-configuration-user                 ; string
+                 (default "root"))
+  (group         rsync-configuration-group                ; string
+                 (default "root"))
+  (uid           rsync-configuration-uid                  ; string
+                 (default "rsyncd"))
+  (gid           rsync-configuration-gid                  ; string
+                 (default "rsyncd")))
+
+(define (rsync-account config)
+  "Return the user accounts and user groups for CONFIG."
+  (let ((rsync-user (if (rsync-configuration-uid config)
+                        (rsync-configuration-uid config)
+                        (rsync-configuration-user config)))
+        (rsync-group (if (rsync-configuration-gid config)
+                         (rsync-configuration-gid config)
+                         (rsync-configuration-group config))))
+    (list (user-group (name rsync-group) (system? #t))
+          (user-account
+           (name rsync-user)
+           (system? #t)
+           (group rsync-group)
+           (comment "rsyncd privilege separation user")
+           (home-directory (string-append "/var/run/"
+                                          rsync-user))
+           (shell #~(string-append #$shadow "/sbin/nologin"))))))
+
+(define (rsync-activation config)
+  "Return the activation GEXP for CONFIG."
+  (with-imported-modules '((guix build utils))
+    #~(begin
+        (let ((share-directory  #$(rsync-configuration-share-path config))
+              (user  (getpw (if #$(rsync-configuration-uid config)
+                                #$(rsync-configuration-uid config)
+                                #$(rsync-configuration-user config))))
+              (group (getpw (if #$(rsync-configuration-gid config)
+                                #$(rsync-configuration-gid config)
+                                #$(rsync-configuration-group config)))))
+          (mkdir-p (dirname #$(rsync-configuration-pid-file config)))
+          (and=> share-directory mkdir-p)
+          (chown share-directory
+                 (passwd:uid user)
+                 (group:gid group))))))
+
+(define rsync-config-file
+  ;; Return the rsync configuration file corresponding to CONFIG.
+  (match-lambda
+    (($ <rsync-configuration> package port-number pid-file lock-file log-file
+                              use-chroot? share-path share-comment read-only?
+                              timeout user group uid gid)
+     (if (not (string=? user "root"))
+         (cond
+          ((<= port-number 1024)
+           (error (string-append "rsync-service: to run on port "
+                                 (number->string port-number)
+                                 ", user must be root.")))
+          (use-chroot?
+           (error (string-append "rsync-service: to run in a chroot"
+                                 ", user must be root.")))
+          (uid
+           (error "rsync-service: to use uid, user must be root."))
+          (gid
+           (error "rsync-service: to use gid, user must be root."))))
+     (mixed-text-file
+      "rsync.conf"
+      "# Generated by 'rsync-service'.\n\n"
+      "pid file = " pid-file "\n"
+      "lock file = " lock-file "\n"
+      "log file = " log-file "\n"
+      "port = " (number->string port-number) "\n"
+      "use chroot = " (if use-chroot? "true" "false") "\n"
+      (if uid (string-append "uid = " uid "\n") "")
+      "gid = " (if gid gid "nogroup") "\n" ; no group nobody
+      "\n"
+      "[files]\n"
+      "path = " share-path "\n"
+      "comment = " share-comment "\n"
+      "read only = " (if read-only? "true" "false") "\n"
+      "timeout = " (number->string timeout) "\n"))))
+
+(define (rsync-shepherd-service config)
+  "Return a <shepherd-service> for rsync with CONFIG."
+  (let* ((rsync       (rsync-configuration-package config))
+         (pid-file    (rsync-configuration-pid-file config))
+         (port-number (rsync-configuration-port-number config))
+         (user        (rsync-configuration-user config))
+         (group       (rsync-configuration-group config)))
+    (list (shepherd-service
+           (provision '(rsync))
+           (documentation "Run rsync daemon.")
+           (start #~(make-forkexec-constructor
+                     (list (string-append #$rsync "/bin/rsync")
+                           "--config" #$(rsync-config-file config)
+                           "--daemon")
+                     #:pid-file #$pid-file
+                     #:user #$user
+                     #:group #$group))
+           (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 rsync-account)
+          (service-extension activation-service-type rsync-activation)))
+   (default-value (rsync-configuration))))

gnu/tests/rsync.scm

@@ -0,0 +1,126 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2017 Christopher Baines <mail@cbaines.net>
+;;;
+;;; 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 tests rsync)
+  #:use-module (gnu packages rsync)
+  #:use-module (gnu tests)
+  #:use-module (gnu system)
+  #:use-module (gnu system file-systems)
+  #:use-module (gnu system shadow)
+  #:use-module (gnu system vm)
+  #:use-module (gnu services)
+  #:use-module (gnu services rsync)
+  #:use-module (gnu services networking)
+  #:use-module (guix gexp)
+  #:use-module (guix store)
+  #:export (%test-rsync))
+
+(define* (run-rsync-test rsync-os #:optional (rsync-port 873))
+  "Run tests in %RSYNC-OS, which has rsync running and listening on
+PORT."
+  (define os
+    (marionette-operating-system
+     rsync-os
+     #:imported-modules '((gnu services herd)
+                          (guix combinators))))
+
+  (define vm
+    (virtual-machine
+     (operating-system os)
+     (port-forwardings '())))
+
+  (define test
+    (with-imported-modules '((gnu build marionette))
+      #~(begin
+          (use-modules (srfi srfi-11) (srfi srfi-64)
+                       (gnu build marionette))
+
+          (define marionette
+            (make-marionette (list #$vm)))
+
+          (mkdir #$output)
+          (chdir #$output)
+
+          (test-begin "rsync")
+
+          ;; Wait for rsync to be up and running.
+          (test-eq "service running"
+            'running!
+            (marionette-eval
+             '(begin
+                (use-modules (gnu services herd))
+                (start-service 'rsync)
+                'running!)
+             marionette))
+
+          ;; Make sure the PID file is created.
+          (test-assert "PID file"
+            (marionette-eval
+             '(file-exists? "/var/run/rsyncd/rsyncd.pid")
+             marionette))
+
+          (test-assert "Test file copied to share"
+            (marionette-eval
+             '(begin
+                (call-with-output-file "/tmp/input"
+                  (lambda (port)
+                    (display "test-file-contents\n" port)))
+                (zero?
+                 (system* "rsync" "/tmp/input"
+                          (string-append "rsync://localhost:"
+                                         (number->string #$rsync-port)
+                                         "/files/input"))))
+             marionette))
+
+          (test-equal "Test file correctly received from share"
+            "test-file-contents"
+            (marionette-eval
+             '(begin
+                (use-modules (ice-9 rdelim))
+                (zero?
+                 (system* "rsync"
+                          (string-append "rsync://localhost:"
+                                         (number->string #$rsync-port)
+                                         "/files/input")
+                          "/tmp/output"))
+                (call-with-input-file "/tmp/output"
+                  (lambda (port)
+                    (read-line port))))
+             marionette))
+
+          (test-end)
+          (exit (= (test-runner-fail-count (test-runner-current)) 0)))))
+
+  (gexp->derivation "rsync-test" test))
+
+(define* %rsync-os
+  ;; Return operating system under test.
+  (let ((base-os
+         (simple-operating-system
+          (dhcp-client-service)
+          (service rsync-service-type))))
+    (operating-system
+      (inherit base-os)
+      (packages (cons* rsync
+                       (operating-system-packages base-os))))))
+
+(define %test-rsync
+  (system-test
+   (name "rsync")
+   (description "Connect to a running RSYNC server.")
+   (value (run-rsync-test %rsync-os))))