[management, client] Add management-controlled client metrics push

Allow enabling/disabling client metrics push from the dashboard via
account settings instead of requiring env vars on every client.

- Add MetricsConfig proto message to NetbirdConfig
- Add MetricsPushEnabled to account Settings (DB-persisted)
- Expose metrics_push_enabled in OpenAPI and dashboard API handler
- Populate MetricsConfig in sync and login responses
- Client dynamically starts/stops push based on management config
- NB_METRICS_PUSH_ENABLED env var overrides management when explicitly set
- Add activity events for metrics push enable/disable

client/internal/connect.go

@@ -291,6 +291,10 @@ func (c *ConnectClient) run(mobileDependency MobileDependency, runningChan chan
 		c.clientMetrics.RecordLoginDuration(engineCtx, time.Since(loginStarted), true)
 		c.statusRecorder.MarkManagementConnected()
 
+		if metricsConfig := loginResp.GetNetbirdConfig().GetMetrics(); metricsConfig != nil {
+			c.clientMetrics.UpdatePushFromMgm(c.ctx, metricsConfig.GetEnabled())
+		}
+
 		localPeerState := peer.LocalPeerState{
 			IP:              loginResp.GetPeerConfig().GetAddress(),
 			PubKey:          myPrivateKey.PublicKey().String(),

client/internal/engine.go

@@ -888,6 +888,8 @@ func (e *Engine) handleSync(update *mgmProto.SyncResponse) error {
 			return fmt.Errorf("handle the flow configuration: %w", err)
 		}
 
+		e.handleMetricsUpdate(wCfg.GetMetrics())
+
 		if err := e.PopulateNetbirdConfig(wCfg, nil); err != nil {
 			log.Warnf("Failed to update DNS server config: %v", err)
 		}
@@ -964,6 +966,15 @@ func (e *Engine) handleFlowUpdate(config *mgmProto.FlowConfig) error {
 	return e.flowManager.Update(flowConfig)
 }
 
+func (e *Engine) handleMetricsUpdate(config *mgmProto.MetricsConfig) {
+	if config == nil {
+		log.Debugf("no metrics configuration received from management")
+		return
+	}
+	log.Infof("received metrics configuration from management: enabled=%v", config.GetEnabled())
+	e.clientMetrics.UpdatePushFromMgm(e.ctx, config.GetEnabled())
+}
+
 func toFlowLoggerConfig(config *mgmProto.FlowConfig) (*nftypes.FlowConfig, error) {
 	if config.GetInterval() == nil {
 		return nil, errors.New("flow interval is nil")

client/internal/metrics/env.go

@@ -60,6 +60,13 @@ func getMetricsInterval() time.Duration {
 	return interval
 }
 
+// isMetricsPushEnvSet returns true if NB_METRICS_PUSH_ENABLED is explicitly set (to any value).
+// When set, the env var takes full precedence over management server configuration.
+func isMetricsPushEnvSet() bool {
+	_, set := os.LookupEnv(EnvMetricsPushEnabled)
+	return set
+}
+
 func isForceSending() bool {
 	force, _ := strconv.ParseBool(os.Getenv(EnvMetricsForceSending))
 	return force

client/internal/metrics/metrics.go

@@ -169,7 +169,7 @@ func (c *ClientMetrics) Export(w io.Writer) error {
 	return c.impl.Export(w)
 }
 
-// StartPush starts periodic pushing of metrics with the given configuration
+// StartPush starts periodic pushing of metrics with the given configuration.
 // Precedence: PushConfig.ServerAddress > remote config server_url
 func (c *ClientMetrics) StartPush(ctx context.Context, config PushConfig) {
 	if c == nil {
@@ -184,6 +184,53 @@ func (c *ClientMetrics) StartPush(ctx context.Context, config PushConfig) {
 		return
 	}
 
+	c.startPushLocked(ctx, config)
+}
+
+// StopPush stops the periodic metrics push.
+func (c *ClientMetrics) StopPush() {
+	if c == nil {
+		return
+	}
+	c.pushMu.Lock()
+	defer c.pushMu.Unlock()
+
+	c.stopPushLocked()
+}
+
+// UpdatePushFromMgm updates metrics push based on management server configuration.
+// If NB_METRICS_PUSH_ENABLED is explicitly set (true or false), management config is ignored.
+// When unset, management controls whether push is enabled.
+func (c *ClientMetrics) UpdatePushFromMgm(ctx context.Context, enabled bool) {
+	if c == nil {
+		return
+	}
+
+	if isMetricsPushEnvSet() {
+		log.Debugf("ignoring management config, env var is explicitly set: %s", EnvMetricsPushEnabled)
+		return
+	}
+
+	c.pushMu.Lock()
+	defer c.pushMu.Unlock()
+
+	if enabled {
+		if c.push != nil {
+			return
+		}
+		log.Infof("enabled metrics push by management")
+		c.startPushLocked(ctx, PushConfigFromEnv())
+	} else {
+		if c.push == nil {
+			return
+		}
+		log.Infof("disabled metrics push by managmenet")
+		c.stopPushLocked()
+	}
+}
+
+// startPushLocked starts push. Caller must hold pushMu.
+func (c *ClientMetrics) startPushLocked(ctx context.Context, config PushConfig) {
 	c.mu.RLock()
 	agentVersion := c.agentInfo.Version
 	peerID := c.agentInfo.peerID
@@ -208,12 +255,8 @@ func (c *ClientMetrics) StartPush(ctx context.Context, config PushConfig) {
 	c.push = push
 }
 
-func (c *ClientMetrics) StopPush() {
-	if c == nil {
-		return
-	}
-	c.pushMu.Lock()
-	defer c.pushMu.Unlock()
+// stopPushLocked stops push. Caller must hold pushMu.
+func (c *ClientMetrics) stopPushLocked() {
 	if c.push == nil {
 		return
 	}