> From 85ce8270afdfe4255ee5ebf0e185e99dcef8ad13 Mon Sep 17 00:00:00 2001
> From: Oleg Pykhalov <go.wigust <at> gmail.com>
> Date: Thu, 27 Jul 2017 04:01:01 +0300
> Subject: [PATCH] gnu: Add rsync service.
> 
> * 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.
> * gnu/tests/rsync.scm: New file.
> * gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
> ---
>  doc/guix.texi          |  74 ++++++++++++++++++++
>  gnu/local.mk           |   2 +
>  gnu/services/rsync.scm | 181
> +++++++++++++++++++++++++++++++++++++++++++++++++
> gnu/tests/rsync.scm    | 128 ++++++++++++++++++++++++++++++++++ 4
> files changed, 385 insertions(+) create mode 100644
> gnu/services/rsync.scm create mode 100644 gnu/tests/rsync.scm

Thanks for picking this up again Oleg, the changes you've made look
really good.

> diff --git a/doc/guix.texi b/doc/guix.texi
> index 1356a357c..77c99e069 100644
> --- a/doc/guix.texi
> +++ b/doc/guix.texi
> @@ -16869,6 +16869,80 @@ Extra options will be passed to @code{git
> daemon}, please run @end table
>  @end deftp
>  
> +@subsubsection Incremental file transfer

Ideally this wouldn't be in Miscellaneous Services as I don't think
that is very helpful for users discovering what services Guix offers.
I think Networking Services might be better, what do you think? It
includes things like Tor, which are about using networks, and not
about core networking. 

> +
> +The @code{(gnu services rsync)} module provides the following
> services: +
> +@subsubheading Rsync service
> +
> +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 daemon,
> +@command{rsync-configuration} record as in this example:

@uref{https://rsync.samba.org, rsync} looks nicer to me here.

> +
> +@example
> +(service rsync-service-type
> +         (rsync-configuration))
> +@end example

You may as well give the simpler (service rsync-service-type) version
here now that the service-type has a default value.

> +
> +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} will be started as
> the +@code{root} user and group.

I think this needs to read "needs to be" rather than "will be".

> +
> +@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. 

I'm not sure what "module" is here.

> +@end table
> +@end deftp
> +
>  @node Setuid Programs
>  @subsection Setuid Programs
>  
> diff --git a/gnu/local.mk b/gnu/local.mk
> index 418cc5e2a..fd252118d 100644
> --- a/gnu/local.mk
> +++ b/gnu/local.mk
> @@ -451,6 +451,7 @@ 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				\
> @@ -497,6 +498,7 @@ 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
> diff --git a/gnu/services/rsync.scm b/gnu/services/rsync.scm
> new file mode 100644
> index 000000000..18c46ecfb
> --- /dev/null
> +++ b/gnu/services/rsync.scm
> @@ -0,0 +1,181 @@
> +;;; GNU Guix --- Functional package management for GNU
> +;;; Copyright © 2017 Oleg Pykhalov <go.wigust <at> 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."
> +  #~(begin
> +      (use-modules (guix build utils))

Using with-imported-modules with this gexp here would be good, to
ensure it has the (guix build utils) module.

> +      (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 config)
> +  "Return the rsync configuration file corresponding to CONFIG."
> +  (let ((port-number   (rsync-configuration-port-number config))
> +        (pid-file      (rsync-configuration-pid-file config))
> +        (lock-file     (rsync-configuration-lock-file config))
> +        (log-file      (rsync-configuration-log-file config))
> +        (use-chroot?   (rsync-configuration-use-chroot? config))
> +        (share-path    (rsync-configuration-share-path config))
> +        (share-comment (rsync-configuration-share-comment config))
> +        (read-only?    (rsync-configuration-read-only? config))
> +        (timeout       (rsync-configuration-timeout config))
> +        (user          (rsync-configuration-user config))
> +        (group         (rsync-configuration-group config))
> +        (uid           (rsync-configuration-uid config))
> +        (gid           (rsync-configuration-gid config)))

Using match, or match-lambda might neaten this up a bit. There are a
few examples of using this in Guix.

> +    (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))))
> diff --git a/gnu/tests/rsync.scm b/gnu/tests/rsync.scm
> new file mode 100644
> index 000000000..691b88e0d
> --- /dev/null
> +++ b/gnu/tests/rsync.scm
> @@ -0,0 +1,128 @@
> +;;; GNU Guix --- Functional package management for GNU

[...]

> +
> +(define %test-rsync
> +  (system-test
> +   (name "rsync")
> +   (description "Connect to a running RSYNC server.")
> +   (value (run-rsync-test (%rsync-os)))))
> -- 
> 2.14.1

I'm pretty happy with this now. I think updating the documentation to
match the recent changes in the service would be good to do before
merging this but that is all. Good job :)