Re: [PATCH] gnu: rottlog: rotate messages daily.

[Ludovic Courtès]

Hello!

Jan Nieuwenhuizen <address@hidden> skribis:

>>> ‘rottlog’ was looking for config files in OUT/etc, which made it
>>> impossible for people to configure it.  So in commit
>>> 268ad34e0eadf8a015798b5c5587aad65b9f3a61 I changed it to look for
>>> configuration files in /etc/rottlog.
>>>
>>> Consequently, running “rottlog” alone won’t work; one has to provide
>>> /etc/rottlog/{rc,daily} first.  We should have a GuixSD service that
>>> does that.
>>
>> Ah, yes configuration was the bit I was wondering about.  A service
>> that initializes/writes these sounds like a good idea!
>
> I made an attempt at a simple version of such a service.  Its currently
> just copying rc and writing a daily/weekly, find a working example
> attached.

Great!  Comments below.

> From cf93c7b59d0dc71ff23b4f9d435106d3844a9b9a Mon Sep 17 00:00:00 2001
> From: Jan Nieuwenhuizen <address@hidden>
> Date: Thu, 8 Sep 2016 01:20:43 +0200
> Subject: [PATCH] gnu: services: add rottlog.
>
> * gnu/services/admin.scm: New file.
> * gnu/local.mk (GNU_SYSTEM_MODULES): Add it.

[...]

> +;;;  Add to operating-system services
> +;;;
> +;;;     (mcron-service (list rottlog-job))
> +;;;     (rottlog-service)

It’s possible to make it so that users only need to write:

  (mcron-service) (rottlog-service)

(See below.)

> +(define-record-type* <rottlog-configuration>
> +  rottlog-configuration make-rottlog-configuration
> +  rottlog-configuration?
> +  (period rottlog-period)
> +  (initialize? rottlog-initialize?))

It should also have a ‘rottlog’ field, to specify the rottlog package
being used.

> +(define (rottlog-initialization period)
> +  "Return the gexp to initialize the ROTTLOG service for PERIOD."
> +  #~(begin
> +      (use-modules (ice-9 rdelim))
> +      (let* ((dir "/etc/rottlog")
> +             (period-config (format #f "~a/~a" dir '#$period))
> +             (rc-config (string-append dir "/rc")))
> +
> +        (mkdir-p dir)
> +
> +        ;; TODO: substitutions
> +        (unless (file-exists? rc-config)
> +          (format #t "creating rottlog config '~a'...~%" rc-config)
> +          (let* ((file (open-file rc-config "w"))
> +                 (template (string-append #$rottlog "/etc/rc"))
> +                 (config (with-input-from-file template read-string)))
> +            (display config file)
> +            (close file)))
> +
> +        ;; TODO: list of periods?
> +        (if (not (memq '#$period '(hourly daily weekly)))
> +            (format (current-error-port) "cowardly refusing to create 
> rottlog config for unknown period: '~a'~%" '#$period)
> +            (unless (file-exists? period-config)
> +              (format #t "creating rottlog config'~a'...~%" period-config)
> +              (let* ((file (open-file period-config "w")))
> +                (format file "/var/log/messages {
> +     sharedscripts
> +     postrotate
> +             ~a/bin/kill -HUP $(~a/bin/cat /var/run/syslog.pid) 2> /dev/null
> +     endscript
> +     nocompress
> +}
> +" #$coreutils #$coreutils)
> +                (close file)))))))
> +
> +(define (rottlog-activation config)
> +  "Return the activation gexp for CONFIG."
> +  #~(begin
> +      #$(if (rottlog-initialize? config)
> +            (rottlog-initialization (rottlog-period config))
> +            #t)))

I think it’d be best to let the user pass the files, and put them in
/etc/rottlog by extending ‘etc-service-type’.

> +(define rottlog-service-type
> +  (service-type (name 'rottlog)
> +                (extensions
> +                 (list (service-extension activation-service-type
> +                                          rottlog-activation)))))

Thus, this would also extend mcron-service-type and etc-service-type.

> +(define* (rottlog-service #:key (period 'daily) (initialize? #t))
> +  (service rottlog-service-type
> +           (rottlog-configuration (period period)
> +                                  (initialize? initialize?))))

The configuration probably contain something like an list of name/config
pairs as well as an ‘rc’ file, along these lines:

  (rottlog-configuration
    (periods `(("weekly" . ,(file-append rottlog "/etc/weekly))
               ("daily" . ,(plain-file "daily" "…"))))
    (rc-file (file-append rottlog "/etc/rc")))

That way users would have all the latitude to configure the behavior of
rottlog.

Of course we should provide default config values that take care of
common files such as /var/log/{messages,Xorg.0.log} in a reasonable way.

WDYT?

Thank you!

Ludo’.