fix: thread StatusSocketPath through autopilot controllers

[kimjune01]

Description

Autopilot hardcoded status.DefaultSocketPath in multiple controllers, breaking --status-socket and custom --run-dir configurations. The socket path configured via CfgVars.StatusSocketPath was never threaded through to autopilot's signal controllers or the cron updater.

This adds StatusSocketPath to RootConfig and passes it through:

• signal.RegisterControllers → k0s.RegisterControllers
• restart / restarted reconcilers (version check and PID lookup)
• updates.RegisterControllers → newCronUpdater (status info fetch)

Falls back to status.DefaultSocketPath when StatusSocketPath is empty, preserving existing behavior for default configurations.

Fixes #6750

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

Verified the StatusSocketPath propagation manually by tracing the call chain from component/controller/autopilot.go and component/worker/autopilot.go through to each consumer. All previously hardcoded status.DefaultSocketPath references are replaced with the threaded value.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• My commit messages are signed-off

[twz123]

Thanks! Were you able to test this?

[kimjune01]

No runtime testing yet. The verification was through manual code inspection of the call chain. I can set up a test configuration with --status-socket if that would be helpful for validating the fix.

[kimjune01]

Yes, I've now run the full autopilot unit test suite locally against this branch:

$ go test ./pkg/autopilot/... -count=1
ok   github.com/k0sproject/k0s/pkg/autopilot/channels         0.518s
ok   github.com/k0sproject/k0s/pkg/autopilot/checks            0.889s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller         1.390s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/delegate      2.761s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/plans         2.462s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/plans/cmdprovider/airgapupdate  6.282s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/plans/cmdprovider/k0supdate     3.652s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/plans/cmdprovider/k0supdate/discovery  7.935s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/plans/cmdprovider/k0supdate/utils      1.954s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/plans/core     4.132s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/signal/airgap  5.481s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/signal/common  4.849s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/signal/common/predicate  4.412s
ok   github.com/k0sproject/k0s/pkg/autopilot/controller/signal/k0s     7.166s
ok   github.com/k0sproject/k0s/pkg/autopilot/signaling/v2      7.189s
ok   github.com/k0sproject/k0s/pkg/autopilot/updater            6.175s

go build and go vet also pass clean on all changed packages (pkg/autopilot/..., pkg/component/controller/, pkg/component/worker/).

What I haven't tested: running an actual k0s cluster with --status-socket or a custom --run-dir to confirm the socket path reaches the autopilot controllers at runtime. That would require a multi-node cluster with autopilot enabled, which I don't have set up locally. If there's a preferred integration test setup or a smoke test I should run, happy to do that.

[twz123]

What I haven't tested: running an actual k0s cluster with --status-socket or a custom --run-dir to confirm the socket path reaches the autopilot controllers at runtime. That would require a multi-node cluster with autopilot enabled, which I don't have set up locally. If there's a preferred integration test setup or a smoke test I should run, happy to do that.

You could parameterize one of the existing integration tests to use a custom run dir and a custom status socket. Not sure if it even has to be a multi-node cluster that gets updated? At least for the status socket, the code looks like it should fail for a single node cluster, as well, AFAICT.

I'd try to add a variant for, say, the ap-single integration test à la ap-single-custom-socket or sth. along the lines (see how os.Getenv("K0S_INTTEST_TARGET") is used for parameterization in other inttests), and then see if that's enough to repro the problem. But beware, the AP tests have some ... limitations 🙈: #3719. You might need to double check manually, or fix that issue first 😅

[kimjune01]

Pushed 6a6574c parameterizing ap-single per your suggestion. New target K0S_INTTEST_TARGET=ap-single-custom-socket reuses the existing ap-single package; when set, SetupTest launches the controller with --status-socket=/run/k0s/custom/status.sock --data-dir=/var/lib/k0s-custom, then TestApply runs the same k0supdate Plan it always runs. After the Plan reaches PlanCompleted, the test asserts the custom socket exists and /run/k0s/status.sock does not — that second check is the regression guard against the bug, since prior to this PR the autopilot signal controllers' post-restart probe would have hit the hardcoded default path. (I added it explicitly because of #3719: PlanCompleted alone isn't sufficient evidence the cluster path actually worked.) Wired into smoketests so CI runs it.

Verified locally: go vet ./inttest/ap-single/..., go vet ./pkg/autopilot/..., and a compile-only go test -run NONE ./inttest/ap-single/... all pass; make -n check-ap-single-custom-socket resolves to the expected K0S_INTTEST_TARGET=ap-single-custom-socket go test ... github.com/k0sproject/k0s/inttest/ap-single. The actual bootloose run needs CI — I don't have a Docker-on-Linux setup that can spin the alpine bootloose image. If the post-Plan socket assertions turn out to be too strict on bootloose (e.g. some other component touches /run/k0s/status.sock before the autopilot controllers run), happy to relax to "custom socket exists" only.

[github-actions]

This pull request has merge conflicts that need to be resolved.