nixos testing for NetworkManager

[worldofpeace]

Describe the bug
NetworkManager is a particularly important component and we don't have any tests for it that could block a channel advance.

In particular, a change can happen on nixos-unstable leaving users without functioning networking, and while rollbacks are possible it isn't an excuse to allow that to reach production systems. NixOS doesn't produce a failsafe generation either.

Manual testing is also cumbersome if we want to make a new stable release.

Upstream NetworkManager does have some integration testing

• https://github.com/NetworkManager/NetworkManager-ci

but obviously not useful to us.

I think to start, if we at least had a test that verifies the services start without issues would be great.

[teto]

Agreed. While developing tests for the multipath TCP module #59342 I was surprised to see no networkmanager module.
I had some difficulties with the nixos test infrastructure at first because the test infra will by default install a slirp interface (config.virtualisation.qemu.networkingOptions) and it messed up the interface naming. Like I would clear config.virtualisation.qemu.networkingOptions but interfaces would still be named starting from eth1 instead of eth0.
Just thought I would mention it in case the brave soul writing the test is interested in multihoming.
(but that's more a concern I have with the test infra).

[stale]

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[jtojnar]

Bleh.

[stale]

I marked this as stale due to inactivity. → More info

[lf-]

consequences of our inactions #283717