Housekeeping: fix links, remove deprecated labels in examples, use stdlib maps.Copy, etc (#1013)

* Fix ambiguous markdown link, add missing links in `docs/monitoring/metrics.md`.

* Remove deprecated labels from examples and tests.

* Use `maps.Copy()`; replace `< len()` loops with `range` loops.

Author: renormalize

docs/index.md

@@ -55,7 +55,7 @@ If you are looking to try out druid then you can use a [Kind](https://kind.sigs.
   <source src="https://github.com/user-attachments/assets/cfe0d891-f709-4d7f-b975-4300c6de67e4" type="video/mp4">
 </video>
 
-For detailed documentation, see our `/docs` folder. Please find the [index](README.md) here.
+For detailed documentation, see our `/docs` folder. Please find the [index](./README.md) here.
 
 ## Contributions
 

docs/monitoring/metrics.md

@@ -1,12 +1,12 @@
 # Monitoring
 
-etcd-druid uses [Prometheus][prometheus] for metrics reporting. The metrics can be used for real-time monitoring and debugging of compaction jobs.
+etcd-druid uses [Prometheus](https://prometheus.io/) for metrics reporting. The metrics can be used for real-time monitoring and debugging of compaction jobs.
 
 The simplest way to see the available metrics is to cURL the metrics endpoint `/metrics`. The format is described [here](http://prometheus.io/docs/instrumenting/exposition_formats/).
 
-Follow the [Prometheus getting started doc][prometheus-getting-started] to spin up a Prometheus server to collect etcd metrics.
+Follow the [Prometheus getting started doc](https://prometheus.io/docs/prometheus/latest/getting_started/) to spin up a Prometheus server to collect etcd metrics.
 
-The naming of metrics follows the suggested [Prometheus best practices][prometheus-naming]. All compaction related metrics are put under namespace `etcddruid` and the respective subsystems.
+The naming of metrics follows the suggested [Prometheus best practices](https://prometheus.io/docs/practices/naming/). All compaction related metrics are put under namespace `etcddruid` and the respective subsystems.
 
 ## Snapshot Compaction
 

examples/objstore-emulator/etcd-secret-azurite.yaml

@@ -2,7 +2,6 @@ apiVersion: v1
 kind: Secret
 metadata:
   labels:
-    garden.sapcloud.io/role: controlplane
     role: main
   name: etcd-backup-azurite
 type: Opaque

examples/objstore-emulator/etcd-secret-localstack.yaml

@@ -9,7 +9,6 @@ data:
 kind: Secret
 metadata:
   labels:
-    garden.sapcloud.io/role: controlplane
     role: main
   name: etcd-backup-aws
 type: Opaque

internal/metrics/metrics.go

@@ -51,7 +51,7 @@ func GenerateLabelCombinations(labelValues map[string][]string) []map[string]str
 	output := make([]map[string]string, len(combinations))
 	for i, combination := range combinations {
 		labelVals := make(map[string]string, len(labels))
-		for j := 0; j < len(labels); j++ {
+		for j := range labels {
 			labelVals[labels[j]] = combination[j]
 		}
 		output[i] = labelVals
@@ -78,15 +78,15 @@ func getCombinations(valuesList [][]string) [][]string {
 // Output => [[p,q,1,2],[p,q,3,4],[r,s,1,2],[r,s,3,4]]
 func cartesianProduct(a [][]string, b [][]string) [][]string {
 	output := make([][]string, len(a)*len(b))
-	for i := 0; i < len(a); i++ {
-		for j := 0; j < len(b); j++ {
+	for i := range a {
+		for j := range b {
 			arr := make([]string, len(a[i])+len(b[j]))
 			ctr := 0
-			for ii := 0; ii < len(a[i]); ii++ {
+			for ii := range a[i] {
 				arr[ctr] = a[i][ii]
 				ctr++
 			}
-			for jj := 0; jj < len(b[j]); jj++ {
+			for jj := range b[j] {
 				arr[ctr] = b[j][jj]
 				ctr++
 			}
@@ -101,7 +101,7 @@ func cartesianProduct(a [][]string, b [][]string) [][]string {
 // Ex: [p,q,r] -> [[p],[q],[r]]
 func wrapInSlice(s []string) [][]string {
 	output := make([][]string, len(s))
-	for i := 0; i < len(output); i++ {
+	for i := range output {
 		elem := make([]string, 1)
 		elem[0] = s[i]
 		output[i] = elem

test/e2e/utils.go

@@ -9,6 +9,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"maps"
 	"os"
 	"path"
 	"strings"
@@ -81,14 +82,12 @@ var (
 	defaultRoleLabelValue = "main"
 
 	labels = map[string]string{
-		"app":                     "etcd-statefulset",
-		"garden.sapcloud.io/role": "controlplane",
-		roleLabelKey:              defaultRoleLabelValue,
+		"app":        "etcd-statefulset",
+		roleLabelKey: defaultRoleLabelValue,
 	}
 
 	stsLabels = map[string]string{
 		"app":                              "etcd-statefulset",
-		"garden.sapcloud.io/role":          "controlplane",
 		roleLabelKey:                       defaultRoleLabelValue,
 		"networking.gardener.cloud/to-dns": "allowed",
 		"networking.gardener.cloud/to-private-networks": "allowed",
@@ -160,19 +159,15 @@ func getDefaultEtcd(name, namespace, container, prefix string, provider TestProv
 	etcd.Spec.Annotations = stsAnnotations
 
 	labelsCopy := make(map[string]string)
-	for k, v := range labels {
-		labelsCopy[k] = v
-	}
+	maps.Copy(labelsCopy, labels)
 	labelsCopy[roleLabelKey] = provider.Suffix
 	etcd.Labels = labelsCopy
 	etcd.Spec.Selector = &metav1.LabelSelector{
 		MatchLabels: labelsCopy,
 	}
 
 	stsLabelsCopy := make(map[string]string)
-	for k, v := range stsLabels {
-		stsLabelsCopy[k] = v
-	}
+	maps.Copy(stsLabelsCopy, stsLabels)
 	stsLabelsCopy[roleLabelKey] = provider.Suffix
 	etcd.Spec.Labels = stsLabelsCopy
 
@@ -680,7 +675,7 @@ func getPurgeLocalSnapstoreJob(storeContainer, storePrefix string) *batchv1.Job
 	)
 }
 
-func populateEtcd(ctx context.Context, logger logr.Logger, kubeconfigPath, namespace, etcdName, podName, containerName, keyPrefix, valuePrefix string, startKeyNo, endKeyNo int, delay time.Duration) error {
+func populateEtcd(ctx context.Context, logger logr.Logger, kubeconfigPath, namespace, etcdName, podName, containerName, keyPrefix, valuePrefix string, startKeyNo, endKeyNo int, _ time.Duration) error {
 	var (
 		cmd     string
 		stdout  string