1 files changed, 60 insertions, 3 deletions
diff --git a/middleware/kubernetes/kubernetes.go b/middleware/kubernetes/kubernetes.go
index 209e09eb4..87c9fd4a7 100644
--- a/middleware/kubernetes/kubernetes.go
+++ b/middleware/kubernetes/kubernetes.go
@@ -7,11 +7,13 @@ import (
 	"log"
 	"net"
 	"strings"
+	"sync/atomic"
 	"time"
 
 	"github.com/coredns/coredns/middleware"
 	"github.com/coredns/coredns/middleware/etcd/msg"
 	"github.com/coredns/coredns/middleware/pkg/dnsutil"
+	"github.com/coredns/coredns/middleware/pkg/healthcheck"
 	dnsstrings "github.com/coredns/coredns/middleware/pkg/strings"
 	"github.com/coredns/coredns/middleware/proxy"
 	"github.com/coredns/coredns/request"
@@ -32,7 +34,8 @@ type Kubernetes struct {
 	Zones         []string
 	primaryZone   int
 	Proxy         proxy.Proxy // Proxy for looking up names during the resolution process
-	APIEndpoint   string
+	APIServerList []string
+	APIProxy      *apiProxy
 	APICertAuth   string
 	APIClientCert string
 	APIClientKey  string
@@ -173,8 +176,62 @@ func (k *Kubernetes) getClientConfig() (*rest.Config, error) {
 	overrides := &clientcmd.ConfigOverrides{}
 	clusterinfo := clientcmdapi.Cluster{}
 	authinfo := clientcmdapi.AuthInfo{}
-	if len(k.APIEndpoint) > 0 {
-		clusterinfo.Server = k.APIEndpoint
+	if len(k.APIServerList) > 0 {
+		endpoint := k.APIServerList[0]
+		if len(k.APIServerList) > 1 {
+			// Use a random port for api proxy, will get the value later through listener.Addr()
+			listener, err := net.Listen("tcp", "127.0.0.1:0")
+			if err != nil {
+				return nil, fmt.Errorf("failed to create kubernetes api proxy: %v", err)
+			}
+			k.APIProxy = &apiProxy{
+				listener: listener,
+				handler: proxyHandler{
+					HealthCheck: healthcheck.HealthCheck{
+						FailTimeout: 3 * time.Second,
+						MaxFails:    1,
+						Future:      10 * time.Second,
+						Path:        "/",
+						Interval:    5 * time.Second,
+					},
+				},
+			}
+			k.APIProxy.handler.Hosts = make([]*healthcheck.UpstreamHost, len(k.APIServerList))
+			for i, entry := range k.APIServerList {
+
+				uh := &healthcheck.UpstreamHost{
+					Name: strings.TrimPrefix(entry, "http://"),
+
+					CheckDown: func(upstream *proxyHandler) healthcheck.UpstreamHostDownFunc {
+						return func(uh *healthcheck.UpstreamHost) bool {
+
+							down := false
+
+							uh.CheckMu.Lock()
+							until := uh.OkUntil
+							uh.CheckMu.Unlock()
+
+							if !until.IsZero() && time.Now().After(until) {
+								down = true
+							}
+
+							fails := atomic.LoadInt32(&uh.Fails)
+							if fails >= upstream.MaxFails && upstream.MaxFails != 0 {
+								down = true
+							}
+							return down
+						}
+					}(&k.APIProxy.handler),
+				}
+
+				k.APIProxy.handler.Hosts[i] = uh
+			}
+			k.APIProxy.Handler = &k.APIProxy.handler
+
+			// Find the random port used for api proxy
+			endpoint = fmt.Sprintf("http://%s", listener.Addr())
+		}
+		clusterinfo.Server = endpoint
 	} else {
 		cc, err := rest.InClusterConfig()
 		if err != nil {