treewide: deprecate ip-up.target

[groxxda]

Motivation for this change

Systemd upstream provides targets for networking. This also includes a target network-online.target.

I would like to see ip-up.target completely gone.

In this PR I remove / replace most occurrences since some of them were even wrong and could delay startup.

There are still references that I'm unsure about:

• nixos/modules/services/networking/dhcpcd.nix: is this hook really needed?
• nixos/modules/services/networking/avahi-daemon.nix: has ordering wantedBy and before if-up.target which looks plain wrong to me. We should get avahi-daemon closer to upstream definition that also includes socket-activation, but this is out of scope of this PR
• nixos/modules/services/networking/networkmanager.nix: is this really needed?
• nixos/modules/tasks/network-interfaces-scripted.nix: is this needed?
• nixos/modules/virtualisation/nova.nix: this module still uses the jobs interface, which was deprecated when I started using nixos

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • OS X
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

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I would be thankful for comments about the remaining occurrences as well as deprecating ip-up.target in general.

[mention-bot]

@groxxda, thanks for your PR! By analyzing the annotation information on this pull request, we identified @edolstra, @globin and @rbvermaa to be potential reviewers

[grahamc]

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Reviewed 14 of 14 files at r1.
Review status: all files reviewed at latest revision, 2 unresolved discussions.

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nixos/modules/services/network-filesystems/drbd.nix, line 58 [r1] (raw file):

      after = [ "systemd-udev.settle.service" "network.target" ];
      wants = [ "systemd-udev.settle.service" ];
      wantedBy = [ "multi-user.target" ];

Verified upstream: https://apt-browse.org/browse/ubuntu/trusty/main/i386/drbd8-utils/2:8.4.4-1ubuntu1/file/lib/systemd/system/drbd.service

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nixos/modules/virtualisation/azure-agent.nix, line 182 [r1] (raw file):

      wantedBy = [ "multi-user.target" ];
      after = [ "network-online.target" "sshd.service" ];
      wants = [ "network-online.target" ];

I was suspicious this needed to be up sooner, but verified otherwise: https://github.com/Azure/WALinuxAgent/blob/master/init/coreos/cloud-config.yml

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Comments from Reviewable

[edolstra]

Looks good to me.

What did you mean by the dhcpcd hook? The start ip-up.target can obviously be removed, but the try-restart of ntpd is still necessary unless ntpd has suddenly learned how to detect interface changes.

[groxxda]

Rebased to resolve merge conflicts and also added modified dhcpcd networkmanager and network-interfaces-scripted.
Please review whether the new commits look semantically good to you, I'm not an expert for the scripted networking stuff.

[grahamc]

Reviewed 3 of 3 files at r3.
Review status: 16 of 17 files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable

[grahamc]

but untested

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Reviewed 1 of 1 files at r2.
Review status: all files reviewed at latest revision, all discussions resolved, some commit checks broke.

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Comments from Reviewable

[joachifm]

LGTM. Anything holding this back?

[joachifm]

Just a heads up: some networking related tests are now failing https://hydra.nixos.org/eval/1292016#tabs-now-fail

[fpletz]

I'm investigating.

[groxxda]

Thanks @fpletz. Feel free to revert until I find time to look into this.
By the way, is there a sane way to attach to a test vm to debug the failure?

[fpletz]

@groxxda Found some info on https://nixos.org/nixos/manual/index.html#sec-running-nixos-tests and was able to debug with the execute function.

Should be fixed with c58654e.

[groxxda]

Thank you @fpletz for looking into this and fixing it!
I'll bring some 🍻 when we meet next time.