Remove no-op metrics implementation and simplify ClientMetrics constructor

Eliminate unused `noopMetrics` and refactor `ClientMetrics` to always use the VictoriaMetrics implementation. Update associated logic to reflect these changes.

client/internal/engine.go

@@ -279,12 +279,12 @@ func NewEngine(
 		connSemaphore:  semaphoregroup.NewSemaphoreGroup(connInitLimit),
 		probeStunTurn:  relay.NewStunTurnProbe(relay.DefaultCacheTTL),
 		jobExecutor:    jobexec.NewExecutor(),
-		clientMetrics: metrics.NewClientMetrics(metrics.AgentInfo{
-			DeploymentType: deploymentType,
-			Version:        version.NetbirdVersion(),
-		}, true),
 	}
 
+	engine.clientMetrics = metrics.NewClientMetrics(metrics.AgentInfo{
+		DeploymentType: deploymentType,
+		Version:        version.NetbirdVersion()})
+
 	log.Infof("I am: %s", config.WgPrivateKey.PublicKey().String())
 	return engine
 }

client/internal/metrics/metrics.go

@@ -43,16 +43,8 @@ type ConnectionStageTimestamps struct {
 }
 
 // NewClientMetrics creates a new ClientMetrics instance
-// If enabled is true, uses an OpenTelemetry implementation
-// If enabled is false, uses a no-op implementation
-func NewClientMetrics(agentInfo AgentInfo, enabled bool) *ClientMetrics {
-	var impl metricsImplementation
-	if !enabled {
-		impl = &noopMetrics{}
-	} else {
-		impl = newVictoriaMetrics(agentInfo)
-	}
-	return &ClientMetrics{impl: impl}
+func NewClientMetrics(agentInfo AgentInfo) *ClientMetrics {
+	return &ClientMetrics{impl: newVictoriaMetrics(agentInfo)}
 }
 
 // RecordConnectionStages calculates stage durations from timestamps and records them
@@ -62,15 +54,24 @@ func (c *ClientMetrics) RecordConnectionStages(
 	isReconnection bool,
 	timestamps ConnectionStageTimestamps,
 ) {
+	if c == nil {
+		return
+	}
 	c.impl.RecordConnectionStages(ctx, connectionType, isReconnection, timestamps)
 }
 
 // RecordSyncDuration records the duration of sync message processing
 func (c *ClientMetrics) RecordSyncDuration(ctx context.Context, duration time.Duration) {
+	if c == nil {
+		return
+	}
 	c.impl.RecordSyncDuration(ctx, duration)
 }
 
 // Export exports metrics to the writer
 func (c *ClientMetrics) Export(w io.Writer) error {
+	if c == nil {
+		return nil
+	}
 	return c.impl.Export(w)
 }

client/internal/metrics/noop.go

@@ -1,27 +0,0 @@
-package metrics
-
-import (
-	"context"
-	"io"
-	"time"
-)
-
-// noopMetrics is a no-op implementation of metricsImplementation
-type noopMetrics struct{}
-
-func (s *noopMetrics) RecordConnectionStages(
-	_ context.Context,
-	_ ConnectionType,
-	_ bool,
-	_ ConnectionStageTimestamps,
-) {
-	// No-op
-}
-
-func (s *noopMetrics) RecordSyncDuration(_ context.Context, _ time.Duration) {
-	// No-op
-}
-
-func (s *noopMetrics) Export(_ io.Writer) error {
-	return nil
-}