Add basic probe checks

cmd/nginx-k8s-edge-controller/main.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"github.com/nginxinc/kubernetes-nginx-ingress/internal/config"
 	"github.com/nginxinc/kubernetes-nginx-ingress/internal/observation"
+	"github.com/nginxinc/kubernetes-nginx-ingress/internal/probation"
 	"github.com/nginxinc/kubernetes-nginx-ingress/internal/synchronization"
 	"github.com/sirupsen/logrus"
 	"k8s.io/client-go/kubernetes"
@@ -68,6 +69,9 @@ func run() error {
 	go handler.Run(ctx.Done())
 	go synchronizer.Run(ctx.Done())
 
+	probeServer := probation.NewHealthServer()
+	probeServer.Start()
+
 	err = watcher.Watch()
 	if err != nil {
 		return fmt.Errorf(`error occurred watching for events: %w`, err)

deployment/nkl-deployment.yaml

@@ -21,4 +21,20 @@ spec:
               value: "http://10.1.1.4:9000/api"
           image: ciroque/nginx-k8s-edge-controller:latest
           imagePullPolicy: Always
+          ports:
+            - name: http
+              containerPort: 51031
+              protocol: TCP
+          livenessProbe:
+            httpGet:
+              path: /livez
+              port: http
+            initialDelaySeconds: 5
+            periodSeconds: 2
+          readinessProbe:
+            httpGet:
+              path: /readyz
+              port: http
+            initialDelaySeconds: 5
+            periodSeconds: 2
       serviceAccountName: nginx-k8s-edge-controller

internal/probation/check.go

@@ -0,0 +1,30 @@
+// Copyright 2023 f5 Inc. All rights reserved.
+// Use of this source code is governed by the Apache
+// license that can be found in the LICENSE file.
+
+package probation
+
+type Check interface {
+	Check() bool
+}
+
+type LiveCheck struct {
+}
+
+type ReadyCheck struct {
+}
+
+type StartupCheck struct {
+}
+
+func (l *LiveCheck) Check() bool {
+	return true
+}
+
+func (r *ReadyCheck) Check() bool {
+	return true
+}
+
+func (s *StartupCheck) Check() bool {
+	return true
+}

internal/probation/doc.go

@@ -0,0 +1,9 @@
+// Copyright 2023 f5 Inc. All rights reserved.
+// Use of this source code is governed by the Apache
+// license that can be found in the LICENSE file.
+
+/*
+Package probation includes support for Kubernetes health and wellness checks.
+*/
+
+package probation

internal/probation/server.go

@@ -0,0 +1,87 @@
+// Copyright 2023 f5 Inc. All rights reserved.
+// Use of this source code is governed by the Apache
+// license that can be found in the LICENSE file.
+
+package probation
+
+import (
+	"fmt"
+	"github.com/sirupsen/logrus"
+	"net/http"
+)
+
+const (
+	Ok                  = "OK"
+	ServiceNotAvailable = "Service Not Available"
+	ListenPort          = 51031
+)
+
+type HealthServer struct {
+	httpServer   *http.Server
+	LiveCheck    LiveCheck
+	ReadyCheck   ReadyCheck
+	StartupCheck StartupCheck
+}
+
+func NewHealthServer() *HealthServer {
+	return &HealthServer{
+		LiveCheck:    LiveCheck{},
+		ReadyCheck:   ReadyCheck{},
+		StartupCheck: StartupCheck{},
+	}
+}
+
+func (hs *HealthServer) Start() {
+	logrus.Debugf("Starting probe listener on port %d", ListenPort)
+
+	address := fmt.Sprintf(":%d", ListenPort)
+
+	mux := http.NewServeMux()
+	mux.HandleFunc("/livez", hs.HandleLive)
+	mux.HandleFunc("/readyz", hs.HandleReady)
+	mux.HandleFunc("/startupz", hs.HandleStartup)
+	hs.httpServer = &http.Server{Addr: address, Handler: mux}
+
+	go func() {
+		if err := hs.httpServer.ListenAndServe(); err != nil {
+			logrus.Errorf("unable to start probe listener on %s: %v", hs.httpServer.Addr, err)
+		}
+	}()
+
+	logrus.Info("Started probe listener on", hs.httpServer.Addr)
+}
+
+func (hs *HealthServer) Stop() {
+	if err := hs.httpServer.Close(); err != nil {
+		logrus.Errorf("unable to stop probe listener on %s: %v", hs.httpServer.Addr, err)
+	}
+}
+
+func (hs *HealthServer) HandleLive(writer http.ResponseWriter, request *http.Request) {
+	handleProbe(writer, request, &hs.LiveCheck)
+}
+
+func (hs *HealthServer) HandleReady(writer http.ResponseWriter, request *http.Request) {
+	handleProbe(writer, request, &hs.ReadyCheck)
+}
+
+func (hs *HealthServer) HandleStartup(writer http.ResponseWriter, request *http.Request) {
+	handleProbe(writer, request, &hs.StartupCheck)
+}
+
+func handleProbe(writer http.ResponseWriter, _ *http.Request, check Check) {
+	if check.Check() {
+		writer.WriteHeader(http.StatusOK)
+
+		if _, err := fmt.Fprint(writer, Ok); err != nil {
+			logrus.Error(err)
+		}
+
+	} else {
+		writer.WriteHeader(http.StatusServiceUnavailable)
+
+		if _, err := fmt.Fprint(writer, ServiceNotAvailable); err != nil {
+			logrus.Error(err)
+		}
+	}
+}