Re: Knowing which services to restart

[Ludovic Courtès]

Hi,

Carlo Zancanaro <carlo@zancanaro.id.au> skribis:

> On Wed, Jul 08 2020, Pierre Neidhardt wrote:
>> Couldn't Guix be smarter about this?  Or at least provide a less puzzling 
>> message.
>
> This was brought up when we originally implemented upgrading of services on a 
> live system. The discussion about this starts in an email from Ludovic[1], 
> and proceeds from there (although you'll have to skip over some other 
> unrelated conversations).
>
> There are definitely ways that things can be improved. I made an attempt at 
> doing this at the end of 2018[2], but that didn't result in anything being 
> merged into Guix. I don't think we've yet settled on an approach for how to 
> resolve this (and the related issue of automatically upgrading services).
>
> Carlo
>
> [1]: https://issues.guix.info/22039#11
> [2]: https://issues.guix.info/33508

The general issue here is that we cannot safely stop+start a service
without notice, unless the user explicitly said this is OK.
Consequently, in practice, only services that the user explicitly ‘herd
restart’s are up-to-date.  It’s OK when you know you what service you
want to update here and now, but it’s suboptimal otherwise.

I figured there’s one way to mostly sidestep the issue: when we have
“socket activation” in the Shepherd, then unused services will be
“stopped” at reconfigure time and thus safe to upgrade.  Thus, in
practice, more services will be upgraded by default.

It’d still be up to the user to restart currently running services when
they deem appropriate.

Thanks,
Ludo’.