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cmd/k8s-operator: move TruncateLabelValue to shared k8s-operator package

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Move the label truncation helper to k8s-operator/utils.go so it can be
reused by other components that need to produce valid Kubernetes labels.

Signed-off-by: Daniel Pañeda <daniel.paneda@clickhouse.com>
Signed-off-by: chaosinthecrd <tom@tmlabs.co.uk>
This commit is contained in:
Daniel Pañeda 2026-04-06 16:32:01 +02:00 committed by chaosinthecrd
parent 4b12f9c6af
commit 37dda42f75
No known key found for this signature in database
GPG Key ID: 52ED56820AF046EE
4 changed files with 100 additions and 93 deletions
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27
cmd/k8s-operator/metrics_resources.go
View File

@ -7,8 +7,6 @@ package main
import (
"context"
"crypto/sha256"
"encoding/hex"
"fmt"
"maps"
"reflect"
@ -21,6 +19,7 @@ import (
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/types"
"sigs.k8s.io/controller-runtime/pkg/client"
kube "tailscale.com/k8s-operator"
tsapi "tailscale.com/k8s-operator/apis/v1alpha1"
"tailscale.com/kube/kubetypes"
)
@ -229,13 +228,13 @@ func metricsResourceLabels(opts *metricsOpts) map[string]string {
kubetypes.LabelManaged: "true",
labelMetricsTarget: opts.proxyStsName,
labelPromProxyType: opts.proxyType,
labelPromProxyParentName: truncateLabelValue(opts.proxyLabels[LabelParentName]),
labelPromProxyParentName: kube.TruncateLabelValue(opts.proxyLabels[LabelParentName]),
}
// Include namespace label for proxies created for a namespaced type.
if isNamespacedProxyType(opts.proxyType) {
lbls[labelPromProxyParentNamespace] = truncateLabelValue(opts.proxyLabels[LabelParentNamespace])
lbls[labelPromProxyParentNamespace] = kube.TruncateLabelValue(opts.proxyLabels[LabelParentNamespace])
}
lbls[labelPromJob] = truncateLabelValue(promJobName(opts))
lbls[labelPromJob] = kube.TruncateLabelValue(promJobName(opts))
return lbls
}
@ -252,11 +251,11 @@ func promJobName(opts *metricsOpts) string {
func metricsSvcSelector(proxyLabels map[string]string, proxyType string) map[string]string {
sel := map[string]string{
labelPromProxyType: proxyType,
labelPromProxyParentName: truncateLabelValue(proxyLabels[LabelParentName]),
labelPromProxyParentName: kube.TruncateLabelValue(proxyLabels[LabelParentName]),
}
// Include namespace label for proxies created for a namespaced type.
if isNamespacedProxyType(proxyType) {
sel[labelPromProxyParentNamespace] = truncateLabelValue(proxyLabels[LabelParentNamespace])
sel[labelPromProxyParentNamespace] = kube.TruncateLabelValue(proxyLabels[LabelParentNamespace])
}
return sel
}
@ -287,20 +286,6 @@ func isNamespacedProxyType(typ string) bool {
return typ == proxyTypeIngressResource || typ == proxyTypeIngressService
}
// truncateLabelValue truncates a Kubernetes label value to fit within the
// 63-character limit. If the value exceeds the limit, it is truncated and a
// short hash suffix is appended to preserve uniqueness.
func truncateLabelValue(val string) string {
const maxLen = 63
if len(val) <= maxLen {
return val
}
hash := sha256.Sum256([]byte(val))
suffix := hex.EncodeToString(hash[:4]) // 8 hex chars
truncated := val[:maxLen-len(suffix)-1]
return truncated + "-" + suffix
}
func mergeMapKeys(a, b map[string]string) map[string]string {
m := make(map[string]string, len(a)+len(b))
maps.Copy(m, b)

72
cmd/k8s-operator/metrics_resources_test.go
View File

@ -4,75 +4,3 @@
//go:build !plan9
package main
import (
"strings"
"testing"
)
func TestTruncateLabelValue(t *testing.T) {
tests := []struct {
name string
input string
want string // empty means expect input unchanged
}{
{
name: "short value unchanged",
input: "my-service",
},
{
name: "exactly 63 chars unchanged",
input: strings.Repeat("a", 63),
},
{
name: "64 chars gets truncated",
input: strings.Repeat("a", 64),
},
{
name: "very long value gets truncated",
input: "tailscale-nginx-clickhouse-o11y-server-https-with-extra-long-suffix-that-exceeds-limit",
},
{
name: "253 chars (max k8s resource name)",
input: strings.Repeat("x", 253),
},
{
name: "empty string unchanged",
input: "",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got := truncateLabelValue(tt.input)
if len(got) > 63 {
t.Errorf("truncateLabelValue(%q) = %q (len %d), exceeds 63 chars", tt.input, got, len(got))
}
if len(tt.input) <= 63 && got != tt.input {
t.Errorf("truncateLabelValue(%q) = %q, want unchanged input", tt.input, got)
}
if len(tt.input) > 63 && got == tt.input {
t.Errorf("truncateLabelValue(%q) was not truncated", tt.input)
}
})
}
}
func TestTruncateLabelValueDeterministic(t *testing.T) {
input := strings.Repeat("a", 100)
first := truncateLabelValue(input)
for i := 0; i < 10; i++ {
got := truncateLabelValue(input)
if got != first {
t.Fatalf("non-deterministic: got %q, want %q", got, first)
}
}
}
func TestTruncateLabelValueUniqueness(t *testing.T) {
// Two inputs sharing a long prefix but differing at the end should produce different outputs.
a := strings.Repeat("a", 100) + "-one"
b := strings.Repeat("a", 100) + "-two"
if truncateLabelValue(a) == truncateLabelValue(b) {
t.Errorf("collision: %q and %q produce the same truncated label", a, b)
}
}

16
k8s-operator/utils.go
View File

@ -7,6 +7,8 @@
package kube
import (
"crypto/sha256"
"encoding/hex"
"fmt"
"tailscale.com/tailcfg"
@ -50,3 +52,17 @@ func CapVerFromFileName(name string) (tailcfg.CapabilityVersion, error) {
_, err := fmt.Sscanf(name, "cap-%d.hujson", &cap)
return cap, err
}
// TruncateLabelValue truncates a Kubernetes label value to fit within the
// 63-character limit. If the value exceeds the limit, it is truncated and a
// short hash suffix is appended to preserve uniqueness.
func TruncateLabelValue(val string) string {
const maxLen = 63
if len(val) <= maxLen {
return val
}
hash := sha256.Sum256([]byte(val))
suffix := hex.EncodeToString(hash[:4]) // 8 hex chars
truncated := val[:maxLen-len(suffix)-1]
return truncated + "-" + suffix
}

78
k8s-operator/utils_test.go Normal file
View File

@ -0,0 +1,78 @@
// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause
//go:build !plan9
package kube
import (
"strings"
"testing"
)
func TestTruncateLabelValue(t *testing.T) {
tests := []struct {
name string
input string
want string // empty means expect input unchanged
}{
{
name: "short value unchanged",
input: "my-service",
},
{
name: "exactly 63 chars unchanged",
input: strings.Repeat("a", 63),
},
{
name: "64 chars gets truncated",
input: strings.Repeat("a", 64),
},
{
name: "very long value gets truncated",
input: "tailscale-nginx-clickhouse-o11y-server-https-with-extra-long-suffix-that-exceeds-limit",
},
{
name: "253 chars (max k8s resource name)",
input: strings.Repeat("x", 253),
},
{
name: "empty string unchanged",
input: "",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got := TruncateLabelValue(tt.input)
if len(got) > 63 {
t.Errorf("TruncateLabelValue(%q) = %q (len %d), exceeds 63 chars", tt.input, got, len(got))
}
if len(tt.input) <= 63 && got != tt.input {
t.Errorf("TruncateLabelValue(%q) = %q, want unchanged input", tt.input, got)
}
if len(tt.input) > 63 && got == tt.input {
t.Errorf("TruncateLabelValue(%q) was not truncated", tt.input)
}
})
}
}
func TestTruncateLabelValueDeterministic(t *testing.T) {
input := strings.Repeat("a", 100)
first := TruncateLabelValue(input)
for i := 0; i < 10; i++ {
got := TruncateLabelValue(input)
if got != first {
t.Fatalf("non-deterministic: got %q, want %q", got, first)
}
}
}
func TestTruncateLabelValueUniqueness(t *testing.T) {
// Two inputs sharing a long prefix but differing at the end should produce different outputs.
a := strings.Repeat("a", 100) + "-one"
b := strings.Repeat("a", 100) + "-two"
if TruncateLabelValue(a) == TruncateLabelValue(b) {
t.Errorf("collision: %q and %q produce the same truncated label", a, b)
}
}