[#77] Add metrics for HTTP endpoint status

Signed-off-by: Marina Biryukova <m.biryukova@yadro.com>

app.go

@@ -189,6 +189,13 @@ func newGateMetrics(logger *zap.Logger, provider *metrics.GateMetrics, enabled b
 	}
 }
 
+func (m *gateMetrics) isEnabled() bool {
+	m.mu.RLock()
+	defer m.mu.RUnlock()
+
+	return m.enabled
+}
+
 func (m *gateMetrics) SetEnabled(enabled bool) {
 	if !enabled {
 		m.logger.Warn(logs.MetricsAreDisabled)
@@ -200,23 +207,17 @@ func (m *gateMetrics) SetEnabled(enabled bool) {
 }
 
 func (m *gateMetrics) SetHealth(status metrics.HealthStatus) {
-	m.mu.RLock()
-	if !m.enabled {
-		m.mu.RUnlock()
+	if !m.isEnabled() {
 		return
 	}
-	m.mu.RUnlock()
 
 	m.provider.SetHealth(status)
 }
 
 func (m *gateMetrics) SetVersion(ver string) {
-	m.mu.RLock()
-	if !m.enabled {
-		m.mu.RUnlock()
+	if !m.isEnabled() {
 		return
 	}
-	m.mu.RUnlock()
 
 	m.provider.SetVersion(ver)
 }
@@ -231,6 +232,22 @@ func (m *gateMetrics) Shutdown() {
 	m.mu.Unlock()
 }
 
+func (m *gateMetrics) MarkHealthy(endpoint string) {
+	if !m.isEnabled() {
+		return
+	}
+
+	m.provider.MarkHealthy(endpoint)
+}
+
+func (m *gateMetrics) MarkUnhealthy(endpoint string) {
+	if !m.isEnabled() {
+		return
+	}
+
+	m.provider.MarkUnhealthy(endpoint)
+}
+
 func remove(list []string, element string) []string {
 	for i, item := range list {
 		if item == element {
@@ -327,6 +344,7 @@ func (a *app) Serve() {
 		go func(i int) {
 			a.log.Info(logs.StartingServer, zap.String("address", a.servers[i].Address()))
 			if err := a.webServer.Serve(a.servers[i].Listener()); err != nil && err != http.ErrServerClosed {
+				a.metrics.MarkUnhealthy(a.servers[i].Address())
 				a.log.Fatal(logs.ListenAndServe, zap.Error(err))
 			}
 		}(i)
@@ -508,9 +526,11 @@ func (a *app) initServers(ctx context.Context) {
 		}
 		srv, err := newServer(ctx, serverInfo)
 		if err != nil {
+			a.metrics.MarkUnhealthy(serverInfo.Address)
 			a.log.Warn(logs.FailedToAddServer, append(fields, zap.Error(err))...)
 			continue
 		}
+		a.metrics.MarkHealthy(serverInfo.Address)
 
 		a.servers = append(a.servers, srv)
 		a.log.Info(logs.AddServer, fields...)