Auto-register routes based on kubernetes service annotations

2018-05-26 12:31:40 -05:00
parent d3d1f36009
commit 2befd24b4a
7 changed files with 404 additions and 117 deletions
@@ -0,0 +1,122 @@
+package server
+
+import (
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+	"k8s.io/api/core/v1"
+	"k8s.io/apimachinery/pkg/fields"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/cache"
+	"k8s.io/client-go/tools/clientcmd"
+	"net"
+)
+
+type IK8sWatcher interface {
+	Start(kubeConfigFile string) error
+	Stop()
+}
+
+var K8sWatcher IK8sWatcher = &k8sWatcherImpl{}
+
+type k8sWatcherImpl struct {
+	stop chan struct{}
+}
+
+func (w *k8sWatcherImpl) Start(kubeConfigFile string) error {
+	config, err := clientcmd.BuildConfigFromFlags("", kubeConfigFile)
+	if err != nil {
+		return errors.Wrap(err, "Could not load kube config file")
+	}
+
+	clientset, err := kubernetes.NewForConfig(config)
+	if err != nil {
+		return errors.Wrap(err, "Could not create kube clientset")
+	}
+
+	watchlist := cache.NewListWatchFromClient(
+		clientset.CoreV1().RESTClient(),
+		string(v1.ResourceServices),
+		v1.NamespaceAll,
+		fields.Everything(),
+	)
+
+	_, controller := cache.NewInformer(
+		watchlist,
+		&v1.Service{},
+		0,
+		cache.ResourceEventHandlerFuncs{
+			AddFunc: func(obj interface{}) {
+				routableService := extractRoutableService(obj)
+				if routableService != nil {
+					logrus.WithField("routableService", routableService).Debug("ADD")
+
+					Routes.CreateMapping(routableService.externalServiceName, routableService.containerEndpoint)
+				}
+			},
+			DeleteFunc: func(obj interface{}) {
+				routableService := extractRoutableService(obj)
+				if routableService != nil {
+					logrus.WithField("routableService", routableService).Debug("DELETE")
+
+					Routes.DeleteMapping(routableService.externalServiceName)
+				}
+			},
+			UpdateFunc: func(oldObj, newObj interface{}) {
+				oldRoutableService := extractRoutableService(oldObj)
+				newRoutableService := extractRoutableService(newObj)
+				if oldRoutableService != nil && newRoutableService != nil {
+					logrus.WithFields(logrus.Fields{
+						"old": oldRoutableService,
+						"new": newRoutableService,
+					}).Debug("UPDATE")
+
+					Routes.DeleteMapping(oldRoutableService.externalServiceName)
+					Routes.CreateMapping(newRoutableService.externalServiceName, newRoutableService.containerEndpoint)
+				}
+			},
+		},
+	)
+
+	w.stop = make(chan struct{}, 1)
+	logrus.Info("Monitoring kubernetes for minecraft services")
+	go controller.Run(w.stop)
+
+	return nil
+}
+
+func (w *k8sWatcherImpl) Stop() {
+	if w.stop != nil {
+		w.stop <- struct{}{}
+	}
+}
+
+type routableService struct {
+	externalServiceName string
+	containerEndpoint   string
+}
+
+func extractRoutableService(obj interface{}) *routableService {
+	service, ok := obj.(*v1.Service)
+	if !ok {
+		return nil
+	}
+
+	if externalServiceName, exists := service.Annotations["mc-router.itzg.me/externalServerName"]; exists {
+		clusterIp := service.Spec.ClusterIP
+		port := "25565"
+		for _, p := range service.Spec.Ports {
+			if p.Port == 25565 {
+				if p.TargetPort.String() != "" {
+					port = p.TargetPort.String()
+				}
+			}
+		}
+		rs := &routableService{
+			externalServiceName: externalServiceName,
+			containerEndpoint:   net.JoinHostPort(clusterIp, port),
+		}
+		return rs
+	}
+
+	return nil
+}