Debian still having trouble with merged /usr

Posted Apr 9, 2022 2:22 UTC (Sat) by pabs (subscriber, #43278)
In reply to: Debian still having trouble with merged /usr by josh
Parent article: Debian still having trouble with merged /usr

The amount of configuration diversity in /etc is extremely high. I think we need a systemd-esq initiative to solve that. Perhaps the next thing systemd needs is a library for configuration that everything using /etc could switch to.

Debian still having trouble with merged /usr

Posted Apr 9, 2022 9:37 UTC (Sat) by bluca (subscriber, #118303) [Link]

There's already a library that implements this pattern, built by suse, libeconf

Debian still having trouble with merged /usr

Posted Apr 9, 2022 9:39 UTC (Sat) by Cyberax (✭ supporter ✭, #52523) [Link]

libelectra exists, but is ignored by everyone.

Debian still having trouble with merged /usr

Posted Apr 9, 2022 9:51 UTC (Sat) by smurf (subscriber, #17840) [Link] (4 responses)

The problem with this is that there's no easy way to get backward compatibility unless you do something file system-ish.

OpenWRT tries to do something along these lines. Rather than hack the individual services they invented their own data structure (still text based, but a common format – though personally I'd use YAML instead of their scheme) and then generate the service-specific config files from that. Requires a generator script for each service supported that way, of course.

Debian still having trouble with merged /usr

Posted Apr 12, 2022 0:03 UTC (Tue) by pabs (subscriber, #43278) [Link]

Having just had to deal under time pressure with the OpenWRT config vs generated upstream config, where the OpenWRT wiki didn't adequately document the OpenWRT config and the upstream wiki documented the upstream config not the OpenWRT config, I have to say that this is an incredibly bad idea. I essentially had to read through the init script that generates the upstream config, run it under shell tracing and try and guess how to structure the OpenWRT config and what the options were. Since the upstream config is generated by a script containing hard-coded options, it is also possible the OpenWRT generatable upstream config isn't as full-featured as the upstream config, or could be outdated compared to upstream.

OTOH, the OpenWRT approach is *great* in the situation where there is a reasonably complete web app for the config in the Luci web interface. A discoverable graphical interface is often way easier to use than config file formats with a wide range of options, some of which might not be well documented.

Debian still having trouble with merged /usr

Posted Apr 12, 2022 10:05 UTC (Tue) by Cyberax (✭ supporter ✭, #52523) [Link] (2 responses)

One other very interesting approach is https://augeas.net/ - instead of translating a custom text/YAML into configuration files, it provides a uniform interface to most configs. I'm honestly stumped why it's not used more widely.

Debian still having trouble with merged /usr

Posted Apr 12, 2022 11:04 UTC (Tue) by rahulsundaram (subscriber, #21946) [Link] (1 responses)

Augeas is a tool I have used before including via Puppet. It’s error messages can be cryptic and it seems unmaintained now.

Debian still having trouble with merged /usr

Posted Apr 12, 2022 19:56 UTC (Tue) by Cyberax (✭ supporter ✭, #52523) [Link]

Looking at their Github history, there seems to be a fair amount of activity. I guess there's just not that much stuff that needs changing, apart from lense updates.