Hello Christopher,

Christopher Baines <mail@cbaines.net> writes:

> On Sat, 29 Jul 2017 14:03:49 +0300
> Oleg Pykhalov <go.wigust@gmail.com> wrote:
>
>> >> +@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:
>> >> +
>> >> +@example
>> >> +(service rsync-service-type
>> >> +         (rsync-configuration))
>> >> +@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})
>> >> +Package object of the Rsync utility for efficiently transferring
>> >> and +synchronizing files.  
>> >
>> > Object doesn't really fit here, if anything its a record. Also, I
>> > don't think this needs a description of what rsync does, it's
>> > probably clearest to just say that this is the rsync package?  
>> 
>> OK, is it good?
>> 
>>     @code{rsync} package to use.
>
> Yep, in my opinion, that is the right amount of information.
>
>> >> +(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)))))  
>> >
>> > It might be neater here to use mixed-text-file here. It might look
>> > something like...
>> >
>> > (define (rsync-config-file config)
>> >   "Return the rsync configuration file corresponding to CONFIG."
>> >   (match config
>> >     (($ <rsync-configuration> package port-number pid-file lock-file
>> >                               log-file use-chroot? share-path
>> >                               share-comment read-only? timeout)
>> >      (mixed text-file "rsync.conf"
>> >       "# Generated by 'rsync-service'.\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"
>> >       "[files]\n"
>> >       "path = " share-path "\n"
>> >       "comment = " share-comment "\n"
>> >       "read only = " (if read-only? "true" "false") "\n"
>> >       "timeout = " (number->string timeout) "\n"))))

OK, patched.

>> > One thing I tried with the Tailon service, was to define a
>> > gexp-compiler for the record type representing the configuration
>> > file. One really big advantage in the case of Tailon is that it
>> > easily allows the use of a custom file, just by providing a
>> > different gexp.  
>> 
>> So, this way you could provide your existing Tailon config as a file
>> in system declaration?  Nice.
>
> Yep, I think something like the following should just work, but I
> haven't tested it yet.
>
>   (service tailon-service-type
>            (tailon-configuration
>              (config-file (local-file "../tailon.yml"))))
>
> I bring this up, as I think it is great if this is a feature of all
> services, I'm having trouble though working out how you might do that
> in this case, with the use of values in the activation service
> extension. I can see complicated approaches, but nothing simple and
> clear enough.

I tried to apply your work in tailon service, but I have troubles as you
described.  So I just cleaned up code little bit.