Re: Best practices for writing services

[Xinglu Chen <public@yoctocell.xyz>]

On Fri, Mar 19 2021, Joshua Branson wrote:

>> Currently there seems to be two main ways to do this, the first one
>> is the define one or more records for the configuration field of a
>> service using `define-record-type*`, see the tor service in (gnu
>> services networking) for example.  The other method is to use
>> `define-configuration` to declare the configuration fields of a service,
>> see the transmission service in (gnu services file-sharing) for example.
>
> I believe that the first method via define-record-type* seems to be the
> recommended method to do this.  I only say that because I feel like more
> services are defined that way now.  :)

I decided to use `define-record-type*` since the service for mcron is
pretty simple because it is already configured in Guile. :)

> I've been working on a sway service and an endlessh service in my
> hacking videos
> (https://video.hardlimit.com/accounts/joshua_branson/video-channels).

Cool, great to see more videos on Guix, and it's on PeerTube.

> I was running into issues, where I could compile the service, but
> trying to reconfigure my system would result in errors.

The Guile compiler seems to miss quite a few errors in my exprience too.

> The errors messages were a little vague.  I will also say that the
> better method I have found in writing a guix service is to
>
> 1) write the service as simply as possible first.  I personally would
> copy the simplest service that you can find in gnu/services/  and modify
> that via a M-x anzu-query-replace-regexp.  If re-configuring works, make a commit.
>
> 2) If possible, containerize the service.  If it works, make a commit.
>
> 3) Now start adding in all the features you left out before.

Thanks for the suggestions, I will take them into account in the future.