chore: use constants for env variables

The SHARD and POD_NAME variables were defined in different places.

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

cmd/prometheus-config-reloader/main.go

@@ -29,6 +29,7 @@ import (
 	"time"
 
 	logging "github.com/prometheus-operator/prometheus-operator/internal/log"
+	"github.com/prometheus-operator/prometheus-operator/pkg/operator"
 	"github.com/prometheus-operator/prometheus-operator/pkg/versionutil"
 
 	"github.com/alecthomas/kingpin/v2"
@@ -47,8 +48,7 @@ const (
 	defaultRetryInterval = 5 * time.Second  // 5 seconds was the value previously hardcoded in github.com/thanos-io/thanos/pkg/reloader.
 	defaultReloadTimeout = 30 * time.Second // 30 seconds was the default value
 
-	statefulsetOrdinalEnvvar            = "STATEFULSET_ORDINAL_NUMBER"
-	statefulsetOrdinalFromEnvvarDefault = "POD_NAME"
+	statefulsetOrdinalEnvvar = "STATEFULSET_ORDINAL_NUMBER"
 )
 
 func main() {
@@ -69,7 +69,7 @@ func main() {
 	createStatefulsetOrdinalFrom := app.Flag(
 		"statefulset-ordinal-from-envvar",
 		fmt.Sprintf("parse this environment variable to create %s, containing the statefulset ordinal number", statefulsetOrdinalEnvvar)).
-		Default(statefulsetOrdinalFromEnvvarDefault).String()
+		Default(operator.PodNameEnvVar).String()
 
 	listenAddress := app.Flag(
 		"listen-address",

cmd/prometheus-config-reloader/main_test.go

@@ -23,6 +23,8 @@ import (
 	"time"
 
 	"github.com/go-test/deep"
+
+	"github.com/prometheus-operator/prometheus-operator/pkg/operator"
 )
 
 var cases = []struct {
@@ -40,8 +42,8 @@ var cases = []struct {
 func TestCreateOrdinalEnvVar(t *testing.T) {
 	for _, tt := range cases {
 		t.Run(tt.in, func(t *testing.T) {
-			os.Setenv(statefulsetOrdinalFromEnvvarDefault, tt.in)
-			s := createOrdinalEnvvar(statefulsetOrdinalFromEnvvarDefault)
+			os.Setenv(operator.PodNameEnvVar, tt.in)
+			s := createOrdinalEnvvar(operator.PodNameEnvVar)
 			if os.Getenv(statefulsetOrdinalEnvvar) != tt.out {
 				t.Errorf("got %v, want %s", s, tt.out)
 			}

pkg/operator/config_reloader.go

@@ -25,7 +25,17 @@ import (
 	"k8s.io/apimachinery/pkg/util/intstr"
 )
 
-const configReloaderPort = 8080
+const (
+	configReloaderPort = 8080
+
+	// ShardEnvVar is the name of the environment variable injected into the
+	// config-reloader container that contains the shard number.
+	ShardEnvVar = "SHARD"
+
+	// PodNameEnvVar is the name of the environment variable injected in the
+	// config-reloader container that contains the pod name.
+	PodNameEnvVar = "POD_NAME"
+)
 
 // ConfigReloader contains the options to configure
 // a config-reloader container
@@ -152,7 +162,7 @@ func CreateConfigReloader(name string, options ...ReloaderOption) v1.Container {
 		args    = make([]string, 0)
 		envVars = []v1.EnvVar{
 			{
-				Name: "POD_NAME",
+				Name: PodNameEnvVar,
 				ValueFrom: &v1.EnvVarSource{
 					FieldRef: &v1.ObjectFieldSelector{FieldPath: "metadata.name"},
 				},
@@ -225,7 +235,7 @@ func CreateConfigReloader(name string, options ...ReloaderOption) v1.Container {
 
 	if configReloader.shard != nil {
 		envVars = append(envVars, v1.EnvVar{
-			Name:  "SHARD",
+			Name:  ShardEnvVar,
 			Value: strconv.Itoa(int(*configReloader.shard)),
 		})
 	}

pkg/prometheus/promcfg.go

@@ -41,6 +41,8 @@ const (
 	kubernetesSDRoleEndpointSlice = "endpointslice"
 	kubernetesSDRolePod           = "pod"
 	kubernetesSDRoleIngress       = "ingress"
+
+	defaultReplicaExternalLabelName = "prometheus_replica"
 )
 
 var invalidLabelCharRE = regexp.MustCompile(`[^a-zA-Z0-9_]`)
@@ -397,7 +399,7 @@ func (cg *ConfigGenerator) buildExternalLabels() yaml.MapSlice {
 
 	// Do not add the external label if the resulting value is empty.
 	if replicaExternalLabelName != "" {
-		m[replicaExternalLabelName] = "$(POD_NAME)"
+		m[replicaExternalLabelName] = fmt.Sprintf("$(%s)", operator.PodNameEnvVar)
 	}
 
 	for n, v := range cpf.ExternalLabels {
@@ -1372,7 +1374,7 @@ func generateAddressShardingRelabelingRulesWithSourceLabel(relabelings []yaml.Ma
 		{Key: "action", Value: "hashmod"},
 	}, yaml.MapSlice{
 		{Key: "source_labels", Value: []string{"__tmp_hash"}},
-		{Key: "regex", Value: "$(SHARD)"},
+		{Key: "regex", Value: fmt.Sprintf("$(%s)", operator.ShardEnvVar)},
 		{Key: "action", Value: "keep"},
 	})
 }

pkg/prometheus/statefulset.go

@@ -32,12 +32,11 @@ import (
 )
 
 const (
-	defaultReplicaExternalLabelName = "prometheus_replica"
-	StorageDir                      = "/prometheus"
-	ConfDir                         = "/etc/prometheus/config"
-	ConfOutDir                      = "/etc/prometheus/config_out"
-	WebConfigDir                    = "/etc/prometheus/web_config"
-	tlsAssetsDir                    = "/etc/prometheus/certs"
+	StorageDir   = "/prometheus"
+	ConfDir      = "/etc/prometheus/config"
+	ConfOutDir   = "/etc/prometheus/config_out"
+	WebConfigDir = "/etc/prometheus/web_config"
+	tlsAssetsDir = "/etc/prometheus/certs"
 	//TODO: RulesDir should be moved to the server package, since it is not used by the agent.
 	// It is here at the moment because promcfg uses it, and moving as is will cause import cycle error.
 	RulesDir                 = "/etc/prometheus/rules"