trying to write my own herd service

trying to write my own herd service

[Adam Kandur]

Hi guix!
I tried to write my own herd service, that's what i did
```
(define (my-daemon-shepherd-service _)
  (list (shepherd-service
         (documentation "")
         (provision '(go-github-com-KefirTheAutomator-daemon))
         (requirement '(networking))
         (start #~(make-forkexec-constructor
                   (list
                    (string-append
#$go-github-com-KefirTheAutomator-daemon "/bin/daemon")
                    " -pidFile=/var/run/my-daemon.pid"
                    " -logFile=/var/log/my-daemon.log")))
         (stop #~(make-kill-destructor)))))

(define my-daemon-service-type
  (service-type (name 'my-daemon)
                (extensions
                 (list (service-extension shepherd-root-service-type
                                          my-daemon-shepherd-service)))
                (default-value #f)
                (description "")))
```
(go-github-com-KefirTheAutomator-daemon is my dummy daemon that just
creates a process and writes to it's log file).

This was pulled from my channel, but when I am trying to start the
services, it turns of and disables
```
user@workstation ~$ sudo herd status go-github-com-KefirTheAutomator-daemon
Status of go-github-com-KefirTheAutomator-daemon:
  It is stopped.
  It is disabled.
  Provides (go-github-com-KefirTheAutomator-daemon).
  Requires (networking).
  Conflicts with ().
  Will be respawned.
  Last respawned on Sat Nov 05 02:14:33+0300 2022.

```

Can anyone help me to find out what is wrong, I didn't find any
recommendations on writing herd services?

Re: trying to write my own herd service

[Liliana Marie Prikler]

Am Samstag, dem 05.11.2022 um 02:21 +0300 schrieb Adam Kandur:
> Hi guix!
> I tried to write my own herd service, that's what i did
> ```
> (define (my-daemon-shepherd-service _)
>   (list (shepherd-service
>          (documentation "")
>          (provision '(go-github-com-KefirTheAutomator-daemon))
>          (requirement '(networking))
>          (start #~(make-forkexec-constructor
>                    (list
>                     (string-append
> #$go-github-com-KefirTheAutomator-daemon "/bin/daemon")
>                     " -pidFile=/var/run/my-daemon.pid"
>                     " -logFile=/var/log/my-daemon.log")))
>          (stop #~(make-kill-destructor)))))
> 
> (define my-daemon-service-type
>   (service-type (name 'my-daemon)
>                 (extensions
>                  (list (service-extension shepherd-root-service-type
>                                           my-daemon-shepherd-
> service)))
>                 (default-value #f)
>                 (description "")))
> ```
First things first, writing your own shepherd service from Guix adds a
layer of difficulty: Not only do you need to understand shepherd, you
also need to understand how Guix glues things together.  I would
recommend starting with a simple hand-written service, because that
makes it easier to invoke shepherd as a user and inspect its output.

> (go-github-com-KefirTheAutomator-daemon is my dummy daemon that just
> creates a process and writes to it's log file).
> 
> This was pulled from my channel, but when I am trying to start the
> services, it turns of and disables
> ```
> user@workstation ~$ sudo herd status go-github-com-KefirTheAutomator-
> daemon
> Status of go-github-com-KefirTheAutomator-daemon:
>   It is stopped.
>   It is disabled.
>   Provides (go-github-com-KefirTheAutomator-daemon).
>   Requires (networking).
>   Conflicts with ().
>   Will be respawned.
>   Last respawned on Sat Nov 05 02:14:33+0300 2022.
> 
> ```
> 
> Can anyone help me to find out what is wrong, I didn't find any
> recommendations on writing herd services?
Your process probably dies too often, thus causing shepherd to disable
it.  If it is intended to be a one-shot service, mark it as such.  If
not, check there are unfulfilled requirements.

Cheers

Re: trying to write my own herd service

[EuAndreh]

> >          (start #~(make-forkexec-constructor
> >                    (list
> >                     (string-append
> > #$go-github-com-KefirTheAutomator-daemon "/bin/daemon")
> >                     " -pidFile=/var/run/my-daemon.pid"
> >                     " -logFile=/var/log/my-daemon.log")))

[...]

> Your process probably dies too often, thus causing shepherd to disable
> it.

I'd guess that it is dying too often because it is failing to be launched.  The
extra spaces before the "-pidFile" and "-logFile" arguments aren't ignored, like
when in a shell, but are included explicitly.  A contrived equivalent example
is:

    $ ls -l
    total 36
    drwxr-xr-x  6 andreh users 4096 Nov  4 19:42 Desktop
    drwxr-xr-x  7 andreh users 4096 Oct 31 21:07 Documents
    ...
    $ ls '-l'
    total 36
    drwxr-xr-x  6 andreh users 4096 Nov  4 19:42 Desktop
    drwxr-xr-x  7 andreh users 4096 Oct 31 21:07 Documents
    ...
    $ ls ' -l'
    ls: cannot access ' -l': No such file or directory

I believe that a similar thing is happening to the options to your program, and
it is failing to execute because of that.  You could confirm it by looking that
the logs.