NewMainKubelet validates Kubelet config parameters

Fixes issue #3202.
* Validates SyncFrequency and minimum GC age and propagates error to RunKubelet
* Defaults for Kubelet config and minor cleanup
* cmd Kubelet MinimumGCAge to 1m instead of 0

cmd/kubelet/kubelet.go

@@ -57,7 +57,7 @@ var (
 	registryBurst           = flag.Int("registry_burst", 10, "Maximum size of a bursty pulls, temporarily allows pulls to burst to this number, while still not exceeding registry_qps.  Only used if --registry_qps > 0")
 	runonce                 = flag.Bool("runonce", false, "If true, exit after spawning pods from local manifests or remote urls. Exclusive with --etcd_servers and --enable-server")
 	enableDebuggingHandlers = flag.Bool("enable_debugging_handlers", true, "Enables server endpoints for log collection and local running of containers and commands")
-	minimumGCAge            = flag.Duration("minimum_container_ttl_duration", 0, "Minimum age for a finished container before it is garbage collected.  Examples: '300ms', '10s' or '2h45m'")
+	minimumGCAge            = flag.Duration("minimum_container_ttl_duration", 1*time.Minute, "Minimum age for a finished container before it is garbage collected.  Examples: '300ms', '10s' or '2h45m'")
 	maxContainerCount       = flag.Int("maximum_dead_containers_per_container", 5, "Maximum number of old instances of a container to retain per container.  Each container takes up some disk space.  Default: 5.")
 	authPath                = flag.String("auth_path", "", "Path to .kubernetes_auth file, specifying how to authenticate to API server.")
 	cAdvisorPort            = flag.Uint("cadvisor_port", 4194, "The port of the localhost cAdvisor endpoint")

pkg/kubelet/kubelet.go

@@ -61,29 +61,35 @@ type volumeMap map[string]volume.Interface
 
 // New creates a new Kubelet for use in main
 func NewMainKubelet(
-	hn string,
-	dc dockertools.DockerInterface,
-	ec tools.EtcdClient,
-	rd string,
-	ni string,
-	ri time.Duration,
+	hostname string,
+	dockerClient dockertools.DockerInterface,
+	etcdClient tools.EtcdClient,
+	rootDirectory string,
+	networkContainerImage string,
+	resyncInterval time.Duration,
 	pullQPS float32,
 	pullBurst int,
 	minimumGCAge time.Duration,
 	maxContainerCount int,
 	sourcesReady SourcesReadyFn,
 	clusterDomain string,
-	clusterDNS net.IP) *Kubelet {
+	clusterDNS net.IP) (*Kubelet, error) {
+	if resyncInterval <= 0 {
+		return nil, fmt.Errorf("invalid sync frequency %d", resyncInterval)
+	}
+	if minimumGCAge <= 0 {
+		return nil, fmt.Errorf("invalid minimum GC age %d", minimumGCAge)
+	}
 	return &Kubelet{
-		hostname:              hn,
-		dockerClient:          dc,
-		etcdClient:            ec,
-		rootDirectory:         rd,
-		resyncInterval:        ri,
-		networkContainerImage: ni,
+		hostname:              hostname,
+		dockerClient:          dockerClient,
+		etcdClient:            etcdClient,
+		rootDirectory:         rootDirectory,
+		resyncInterval:        resyncInterval,
+		networkContainerImage: networkContainerImage,
 		podWorkers:            newPodWorkers(),
 		dockerIDToRef:         map[dockertools.DockerID]*api.ObjectReference{},
-		runner:                dockertools.NewDockerContainerCommandRunner(dc),
+		runner:                dockertools.NewDockerContainerCommandRunner(dockerClient),
 		httpClient:            &http.Client{},
 		pullQPS:               pullQPS,
 		pullBurst:             pullBurst,
@@ -92,7 +98,7 @@ func NewMainKubelet(
 		sourcesReady:          sourcesReady,
 		clusterDomain:         clusterDomain,
 		clusterDNS:            clusterDNS,
-	}
+	}, nil
 }
 
 type httpGetter interface {
@@ -202,7 +208,7 @@ func (kl *Kubelet) purgeOldest(ids []string) error {
 		if err != nil {
 			return err
 		}
-		if !data.State.Running && (kl.minimumGCAge == 0 || time.Now().Sub(data.State.FinishedAt) > kl.minimumGCAge) {
+		if !data.State.Running && (time.Now().Sub(data.State.FinishedAt) > kl.minimumGCAge) {
 			dockerData = append(dockerData, data)
 		}
 	}

pkg/standalone/standalone.go

@@ -142,6 +142,8 @@ func SimpleRunKubelet(etcdClient tools.EtcdClient, dockerClient dockertools.Dock
 		EnableServer:            true,
 		EnableDebuggingHandlers: true,
 		SyncFrequency:           3 * time.Second,
+		MinimumGCAge:            10 * time.Second,
+		MaxContainerCount:       5,
 	}
 	RunKubelet(&kcfg)
 }
@@ -162,7 +164,11 @@ func RunKubelet(kcfg *KubeletConfig) {
 	}
 
 	cfg := makePodSourceConfig(kcfg)
-	k := createAndInitKubelet(kcfg, cfg)
+	k, err := createAndInitKubelet(kcfg, cfg)
+	if err != nil {
+		glog.Errorf("Failed to create kubelet: %s", err)
+		return
+	}
 	// process pods and exit.
 	if kcfg.Runonce {
 		if _, err := k.RunOnce(cfg.Updates()); err != nil {
@@ -237,11 +243,11 @@ type KubeletConfig struct {
 	Runonce                 bool
 }
 
-func createAndInitKubelet(kc *KubeletConfig, pc *config.PodConfig) *kubelet.Kubelet {
+func createAndInitKubelet(kc *KubeletConfig, pc *config.PodConfig) (*kubelet.Kubelet, error) {
 	// TODO: block until all sources have delivered at least one update to the channel, or break the sync loop
 	// up into "per source" synchronizations
 
-	k := kubelet.NewMainKubelet(
+	k, err := kubelet.NewMainKubelet(
 		kc.Hostname,
 		kc.DockerClient,
 		kc.EtcdClient,
@@ -256,11 +262,15 @@ func createAndInitKubelet(kc *KubeletConfig, pc *config.PodConfig) *kubelet.Kube
 		kc.ClusterDomain,
 		net.IP(kc.ClusterDNS))
 
+	if err != nil {
+		return nil, err
+	}
+
 	k.BirthCry()
 
 	go k.GarbageCollectLoop()
 	go kubelet.MonitorCAdvisor(k, kc.CAdvisorPort)
 	kubelet.InitHealthChecking(k)
 
-	return k
+	return k, nil
 }