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cmd/k8s-operator: truncate long StatefulSet name prefixes (#10343)

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Kubernetes can generate StatefulSet names that are too long and result in invalid Pod revision hash label values.
Calculate whether a StatefulSet name generated for a Service or Ingress
will be too long and if so, truncate it.

Updates tailscale/tailscale#10284

Signed-off-by: Irbe Krumina <irbe@tailscale.com>
This commit is contained in:
Irbe Krumina
2023-11-21 11:20:37 +01:00
committed by GitHub
parent 2c1f14d9e6
commit 66471710f8
4 changed files with 84 additions and 1 deletions
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32
cmd/k8s-operator/sts.go
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@ -21,6 +21,7 @@ import (
apierrors "k8s.io/apimachinery/pkg/api/errors"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
"k8s.io/apiserver/pkg/storage/names"
"sigs.k8s.io/controller-runtime/pkg/client"
"sigs.k8s.io/yaml"
"tailscale.com/client/tailscale"
@ -176,10 +177,39 @@ func (a *tailscaleSTSReconciler) Cleanup(ctx context.Context, logger *zap.Sugare
return true, nil
}
// maxStatefulSetNameLength is maximum length the StatefulSet name can
// have to NOT result in a too long value for controller-revision-hash
// label value (see https://github.com/kubernetes/kubernetes/issues/64023).
// controller-revision-hash label value consists of StatefulSet's name + hyphen + revision hash.
// Maximum label value length is 63 chars. Length of revision hash is 10 chars.
// https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
// https://github.com/kubernetes/kubernetes/blob/v1.28.4/pkg/controller/history/controller_history.go#L90-L104
const maxStatefulSetNameLength = 63 - 10 - 1
// statefulSetNameBase accepts name of parent resource and returns a string in
// form ts-<portion-of-parentname>- that, when passed to Kubernetes name
// generation will NOT result in a StatefulSet name longer than 52 chars.
// This is done because of https://github.com/kubernetes/kubernetes/issues/64023.
func statefulSetNameBase(parent string) string {
base := fmt.Sprintf("ts-%s-", parent)
// Calculate what length name GenerateName returns for this base.
generator := names.SimpleNameGenerator
generatedName := generator.GenerateName(base)
if excess := len(generatedName) - maxStatefulSetNameLength; excess > 0 {
base = base[:len(base)-excess-1] // take extra char off to make space for hyphen
base = base + "-" // re-instate hyphen
}
return base
}
func (a *tailscaleSTSReconciler) reconcileHeadlessService(ctx context.Context, logger *zap.SugaredLogger, sts *tailscaleSTSConfig) (*corev1.Service, error) {
nameBase := statefulSetNameBase(sts.ParentResourceName)
hsvc := &corev1.Service{
ObjectMeta: metav1.ObjectMeta{
GenerateName: "ts-" + sts.ParentResourceName + "-",
GenerateName: nameBase,
Namespace: a.operatorNamespace,
Labels: sts.ChildResourceLabels,
},