expose prometheus metrics endpoint

- expose simple metrics via promhttp handler at /metrics
- move operator and metrics handler into goroutines

Signed-off-by: Chris Krough <[email protected]>

Author: Chris Krough

pkg/server/server.go

@@ -1,6 +1,9 @@
 package server
 
 import (
+	"fmt"
+	"net/http"
+
 	awsscheme "github.com/awslabs/aws-service-operator/pkg/client/clientset/versioned/scheme"
 	"github.com/awslabs/aws-service-operator/pkg/config"
 	opBase "github.com/awslabs/aws-service-operator/pkg/operators/base"
@@ -9,6 +12,8 @@ import (
 	"k8s.io/client-go/kubernetes/scheme"
 	typedcorev1 "k8s.io/client-go/kubernetes/typed/core/v1"
 	"k8s.io/client-go/tools/record"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 )
 
 const controllerName = "aws-service-operator"
@@ -20,25 +25,50 @@ func New(config *config.Config) *Server {
 	}
 }
 
-// Run starts the server to listen to Kubernetes
-func (c *Server) Run(stopChan chan struct{}) {
-	config := c.Config
-	logger := config.Logger
-	logger.Info("getting kubernetes context")
+func (c *Server) exposeMetrics(errChan chan error) {
+	http.Handle("/metrics", promhttp.Handler())
+	err := http.ListenAndServe(":9090", nil)
+	if err != nil {
+		errChan <- fmt.Errorf("unable to expose metrics: %v", err)
+	}
+}
 
+func (c *Server) watchOperatorResources(errChan chan error, stopChan chan struct{}) {
+
+	logger := c.Config.Logger
+
+	logger.Info("getting kubernetes context")
 	awsscheme.AddToScheme(scheme.Scheme)
 	eventBroadcaster := record.NewBroadcaster()
 	eventBroadcaster.StartLogging(logger.Infof)
-	eventBroadcaster.StartRecordingToSink(&typedcorev1.EventSinkImpl{Interface: config.KubeClientset.CoreV1().Events("")})
+	eventBroadcaster.StartRecordingToSink(&typedcorev1.EventSinkImpl{Interface: c.Config.KubeClientset.CoreV1().Events("")})
 	recorder := eventBroadcaster.NewRecorder(scheme.Scheme, corev1.EventSource{Component: controllerName})
-	config.Recorder = recorder
+	c.Config.Recorder = recorder
 
 	// start watching the aws operator resources
-	logger.WithFields(logrus.Fields{"resources": config.Resources}).Info("Watching")
-
-	operators := opBase.New(config) // TODO: remove context and Clientset
+	logger.WithFields(logrus.Fields{"resources": c.Config.Resources}).Info("Watching")
+	operators := opBase.New(c.Config) // TODO: remove context and Clientset
 	err := operators.Watch(corev1.NamespaceAll, stopChan)
 	if err != nil {
-		logger.Infof("error watching operators '%s'\n", err)
+		errChan <- fmt.Errorf("unable to watch resources: %v", err)
 	}
 }
+
+// Run starts the server to listen to Kubernetes
+func (c *Server) Run(stopChan chan struct{}) {
+	config := c.Config
+	logger := config.Logger
+	errChan := make(chan error, 1)
+
+	logger.Info("starting metrics server")
+	go c.exposeMetrics(errChan)
+
+	logger.Info("starting resource watcher")
+	go c.watchOperatorResources(errChan, stopChan)
+
+	err := <-errChan
+	if err != nil {
+		logger.Fatal(err)
+	}
+
+}