first commit

internal/metrics/metrics.go

@@ -0,0 +1,123 @@
+/*
+© Copyright IBM Corporation 2018, 2023
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package metrics contains code to provide metrics for the queue manager
+package metrics
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"time"
+
+	"github.com/ibm-messaging/mq-container/internal/ready"
+	"github.com/ibm-messaging/mq-container/pkg/logger"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+)
+
+const (
+	defaultPort = "9157"
+)
+
+var (
+	metricsEnabled = false
+	// #nosec G112 - this code is changing soon to use https.
+	// for now we will ignore the gosec.
+	metricsServer  = &http.Server{Addr: ":" + defaultPort}
+)
+
+// GatherMetrics gathers metrics for the queue manager
+func GatherMetrics(qmName string, log *logger.Logger) {
+
+	// If running in standby mode - wait until the queue manager becomes active
+	for {
+		status, _ := ready.Status(context.Background(), qmName)
+		if status.ActiveQM() {
+			break
+		}
+		time.Sleep(requestTimeout * time.Second)
+	}
+
+	metricsEnabled = true
+
+	err := startMetricsGathering(qmName, log)
+	if err != nil {
+		log.Errorf("Metrics Error: %s", err.Error())
+		StopMetricsGathering(log)
+	}
+}
+
+// startMetricsGathering starts gathering metrics for the queue manager
+func startMetricsGathering(qmName string, log *logger.Logger) error {
+
+	defer func() {
+		if r := recover(); r != nil {
+			log.Errorf("Metrics Error: %v", r)
+		}
+	}()
+
+	log.Println("Starting metrics gathering")
+
+	// Start processing metrics
+	go processMetrics(log, qmName)
+
+	// Wait for metrics to be ready before starting the Prometheus handler
+	<-startChannel
+
+	// Register metrics
+	metricsExporter := newExporter(qmName, log)
+	err := prometheus.Register(metricsExporter)
+	if err != nil {
+		return fmt.Errorf("Failed to register metrics: %v", err)
+	}
+
+	// Setup HTTP server to handle requests from Prometheus
+	http.Handle("/metrics", promhttp.Handler())
+	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+		// #nosec G104
+		w.Write([]byte("Status: METRICS ACTIVE"))
+	})
+
+	go func() {
+		err = metricsServer.ListenAndServe()
+		if err != nil && err != http.ErrServerClosed {
+			log.Errorf("Metrics Error: Failed to handle metrics request: %v", err)
+			StopMetricsGathering(log)
+		}
+	}()
+
+	return nil
+}
+
+// StopMetricsGathering stops gathering metrics for the queue manager
+func StopMetricsGathering(log *logger.Logger) {
+
+	if metricsEnabled {
+
+		// Stop processing metrics
+		stopChannel <- true
+
+		// Shutdown HTTP server
+		timeout, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		err := metricsServer.Shutdown(timeout)
+		if err != nil {
+			log.Errorf("Failed to shutdown metrics server: %v", err)
+		}
+	}
+}