nixos/test/prometheus-exporters/bird: fix race condition

[mweinelt]

Motivation for this change

https://hydra.nixos.org/build/141423969

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[Ma27]

@mweinelt did the test pass for you? Locally it's hanging with:

bird # [  152.440867] bird_exporter[753]: time="2021-04-19T20:06:34Z" level=error msg="dial unix /var/run/bird.ctl: connect: connection refused" source="metric_collector.go:84"
bird # [  153.456306] bird_exporter[753]: time="2021-04-19T20:06:35Z" level=error msg="dial unix /var/run/bird.ctl: connect: connection refused" source="metric_collector.go:84"
bird # [  154.471430] bird_exporter[753]: time="2021-04-19T20:06:36Z" level=error msg="dial unix /var/run/bird.ctl: connect: connection refused" source="metric_collector.go:84"
bird # [  155.487275] bird_exporter[753]: time="2021-04-19T20:06:37Z" level=error msg="dial unix /var/run/bird.ctl: connect: connection refused" source="metric_collector.go:84"
bird # [  156.502348] bird_exporter[753]: time="2021-04-19T20:06:38Z" level=error msg="dial unix /var/run/bird.ctl: connect: connection refused" source="metric_collector.go:84"

Though I probably wasn't patient enough :)

[mweinelt]

Odd, for me it works. It was racy because the bird socket wouldn't be there yet sometimes.

[Ma27]

@mweinelt how long did the test take for you? As I said, maybe I wasn't patient enough :)

[mweinelt]

nix-build -A nixosTests.prometheus-exporters.bird 1.95s user 0.58s system 11% cpu 21.827 total

[Ma27]

Hmm so way faster than it was the case locally. Let's see what ofborg has to say :)

@ofborg test prometheus-exporters.bird

[mweinelt]

bird # [ 6.428950] bird[682]: Cannot determine router ID, please configure it manually

[mweinelt]

@ofborg test prometheus-exporters.bird