🐛 Checking cert's keypair for nil before accessing to avoid panics

[makhov]

What this PR does / why we need it:

In some circumstances AsFiles() can panic. The PR adds additional nil check for c.KeyPair to avoid it.

2024-02-02T09:15:35Z	INFO	Observed a panic in reconciler: runtime error: invalid memory address or nil pointer dereference	{"controller": "k0scontrollerconfig", "controllerGroup": "bootstrap.cluster.x-k8s.io", "controllerKind": "K0sControllerConfig", "K0sControllerConfig": {"name":"bar-2-1","namespace":"default"}, "namespace": "default", "name": "bar-2-1", "reconcileID": "8a558d44-7dcf-406e-a7e0-e47c895189f6"}
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0x16ca8fd]

goroutine 270 [running]:
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile.func1()
	/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.16.3/pkg/internal/controller/controller.go:116 +0x1e5
panic({0x1a37520?, 0x2e3bb30?})
	/usr/local/go/src/runtime/panic.go:914 +0x21f
sigs.k8s.io/cluster-api/util/secret.(*Certificate).AsFiles(...)
	/go/pkg/mod/sigs.k8s.io/cluster-api@v1.5.3/util/secret/certificates.go:374
sigs.k8s.io/cluster-api/util/secret.Certificates.AsFiles({0xc00035ffb0, 0x4, 0xc0002839b0?})
	/go/pkg/mod/sigs.k8s.io/cluster-api@v1.5.3/util/secret/certificates.go:419 +0xbd
github.com/k0sproject/k0smotron/internal/controller/bootstrap.(*ControlPlaneController).getCerts(0xc000144300, {0x1f94308, 0xc00043cb40}, 0xc000775be0)
	/workspace/internal/controller/bootstrap/controlplane_bootstrap_controller.go:415 +0x1d0
github.com/k0sproject/k0smotron/internal/controller/bootstrap.(*ControlPlaneController).genControlPlaneJoinFiles(0xc000144300, {0x1f94308, 0xc00043cb40}, 0xc000775be0, 0x192b7c0?, {0xc000801fb0, 0x1, 0x1})
	/workspace/internal/controller/bootstrap/controlplane_bootstrap_controller.go:279 +0x19f
github.com/k0sproject/k0smotron/internal/controller/bootstrap.(*ControlPlaneController).Reconcile(0xc000144300, {0x1f94308, 0xc00043cb40}, {{{0xc0006097d0, 0x7}, {0xc0006097c6, 0x7}}})
	/workspace/internal/controller/bootstrap/controlplane_bootstrap_controller.go:180 +0xf7f
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).Reconcile(0x1f97e00?, {0x1f94308?, 0xc00043cb40?}, {{{0xc0006097d0?, 0xb?}, {0xc0006097c6?, 0x0?}}})
	/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.16.3/pkg/internal/controller/controller.go:119 +0xb7
sigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller).reconcileHandler(0xc0002bedc0, {0x1f94340, 0xc0004afa40}, {0x1afb900?, 0xc0003a25c0?})

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):

Fixes k0sproject/k0smotron#438

[k8s-ci-robot]

Hi @makhov. Thanks for your PR.

I'm waiting for a kubernetes-sigs member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[fabriziopandini]

/ok-to-test

For sake of documentation, could you clarify when c.KeyPair could be nil?

[makhov]

We do

certificates := secret.NewCertificatesForInitialControlPlane(config)
err := certificates.Lookup(ctx, client, util.ObjectKey(cluster))
if err != nil {
	return err
}
for _, cert := range certificates.AsFiles() {
   ....
}

If the secret doesn't exist (eg, was removed manually), certificates.Lookup doesn't return an error, but cert.KeyPair is nil.
It might be not the best way of doing things, but I guess, it shouldn't panic anyway.

[fabriziopandini]

Thanks for the explanation, let's add a test case for this scenario, then ok for me

[fabriziopandini]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 78b7fd9f559d0ba2761b693239ab9565b5bb0f15

[chrischdi]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: chrischdi

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[fabriziopandini]

/area util

[sbueringer]

Makes sense

/cherry-pick release-1.7

Let us know if we should cherry-pick it further back

[k8s-infra-cherrypick-robot]

@sbueringer: new pull request created: #10368

In response to this:

Makes sense

/cherry-pick release-1.7

Let us know if we should cherry-pick it further back

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.