Automated cherry pick of #11250

pkg/apiserver/apiserver.go

@@ -131,9 +131,9 @@ func (g *APIGroupVersion) InstallREST(container *restful.Container) error {
 
 // TODO: document all handlers
 // InstallSupport registers the APIServer support functions
-func InstallSupport(mux Mux, ws *restful.WebService, enableResettingMetrics bool) {
+func InstallSupport(mux Mux, ws *restful.WebService, enableResettingMetrics bool, checks ...healthz.HealthzChecker) {
 	// TODO: convert healthz and metrics to restful and remove container arg
-	healthz.InstallHandler(mux)
+	healthz.InstallHandler(mux, checks...)
 	mux.Handle("/metrics", prometheus.Handler())
 	if enableResettingMetrics {
 		mux.HandleFunc("/resetMetrics", metrics.Reset)

pkg/master/master.go

@@ -30,6 +30,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/admission"
@@ -44,6 +45,7 @@ import (
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/auth/handlers"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/fields"
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/healthz"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/labels"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/master/ports"
 	"github.com/GoogleCloudPlatform/kubernetes/pkg/registry/componentstatus"
@@ -77,6 +79,7 @@ import (
 	"github.com/emicklei/go-restful"
 	"github.com/emicklei/go-restful/swagger"
 	"github.com/golang/glog"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 const (
@@ -215,10 +218,13 @@ type Master struct {
 	InsecureHandler http.Handler
 
 	// Used for secure proxy
-	dialer        apiserver.ProxyDialerFunc
-	tunnels       *util.SSHTunnelList
-	tunnelsLock   sync.Mutex
-	installSSHKey InstallSSHKey
+	dialer         apiserver.ProxyDialerFunc
+	tunnels        *util.SSHTunnelList
+	tunnelsLock    sync.Mutex
+	installSSHKey  InstallSSHKey
+	lastSync       int64 // Seconds since Epoch
+	lastSyncMetric prometheus.GaugeFunc
+	clock          util.Clock
 }
 
 // NewEtcdHelper returns an EtcdHelper for the provided arguments or an error if the version
@@ -417,6 +423,8 @@ func logStackOnRecover(panicReason interface{}, httpWriter http.ResponseWriter)
 
 // init initializes master.
 func (m *Master) init(c *Config) {
+	healthzChecks := []healthz.HealthzChecker{}
+	m.clock = util.RealClock{}
 	podStorage := podetcd.NewStorage(c.EtcdHelper, c.KubeletClient)
 	podRegistry := pod.NewRegistry(podStorage.Pod)
 
@@ -526,6 +534,7 @@ func (m *Master) init(c *Config) {
 		m.tunnels = &util.SSHTunnelList{}
 		m.dialer = m.Dial
 		m.setupSecureProxy(c.SSHUser, c.SSHKeyfile, publicKeyFile)
+		m.lastSync = m.clock.Now().Unix()
 
 		// This is pretty ugly.  A better solution would be to pull this all the way up into the
 		// server.go file.
@@ -541,6 +550,11 @@ func (m *Master) init(c *Config) {
 		} else {
 			glog.Errorf("Failed to cast %v to HTTPKubeletClient, skipping SSH tunnel.")
 		}
+		healthzChecks = append(healthzChecks, healthz.NamedCheck("SSH Tunnel Check", m.IsTunnelSyncHealthy))
+		m.lastSyncMetric = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+			Name: "apiserver_proxy_tunnel_sync_latency_secs",
+			Help: "The time since the last successful synchronization of the SSH tunnels for proxy requests.",
+		}, func() float64 { return float64(m.secondsSinceSync()) })
 	}
 
 	apiVersions := []string{}
@@ -557,7 +571,7 @@ func (m *Master) init(c *Config) {
 		apiVersions = append(apiVersions, "v1")
 	}
 
-	apiserver.InstallSupport(m.muxHelper, m.rootWebService, c.EnableProfiling)
+	apiserver.InstallSupport(m.muxHelper, m.rootWebService, c.EnableProfiling, healthzChecks...)
 	apiserver.AddApiWebService(m.handlerContainer, c.APIPrefix, apiVersions)
 	defaultVersion := m.defaultAPIGroupVersion()
 	requestInfoResolver := &apiserver.APIRequestInfoResolver{util.NewStringSet(strings.TrimPrefix(defaultVersion.Root, "/")), defaultVersion.Mapper}
@@ -838,6 +852,20 @@ func (m *Master) getNodeAddresses() ([]string, error) {
 	return addrs, nil
 }
 
+func (m *Master) IsTunnelSyncHealthy(req *http.Request) error {
+	lag := m.secondsSinceSync()
+	if lag > 600 {
+		return fmt.Errorf("Tunnel sync is taking to long: %d", lag)
+	}
+	return nil
+}
+
+func (m *Master) secondsSinceSync() int64 {
+	now := m.clock.Now().Unix()
+	then := atomic.LoadInt64(&m.lastSync)
+	return now - then
+}
+
 func (m *Master) replaceTunnels(user, keyfile string, newAddrs []string) error {
 	glog.Infof("replacing tunnels. New addrs: %v", newAddrs)
 	tunnels := util.MakeSSHTunnels(user, keyfile, newAddrs)
@@ -850,6 +878,7 @@ func (m *Master) replaceTunnels(user, keyfile string, newAddrs []string) error {
 		m.tunnels.Close()
 	}
 	m.tunnels = tunnels
+	atomic.StoreInt64(&m.lastSync, m.clock.Now().Unix())
 	return nil
 }