server.go

/*
Copyright 2014 Google Inc. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

// Package app makes it easy to create a kubelet server for various contexts.
package app

import (
	"fmt"
	"math/rand"
	"net"
	"time"

	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/client"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/clientauth"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/credentialprovider"
	_ "github.com/GoogleCloudPlatform/kubernetes/pkg/healthz"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/config"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/dockertools"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet/volume"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/master/ports"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/tools"
	"github.com/GoogleCloudPlatform/kubernetes/pkg/util"

	"github.com/golang/glog"
	"github.com/spf13/pflag"
)

const defaultRootDir = "/var/lib/kubelet"

// KubeletServer encapsulates all of the parameters necessary for starting up
// a kubelet. These can either be set via command line or directly.
type KubeletServer struct {
	Config                         string
	SyncFrequency                  time.Duration
	FileCheckFrequency             time.Duration
	HTTPCheckFrequency             time.Duration
	ManifestURL                    string
	EnableServer                   bool
	Address                        util.IP
	Port                           uint
	HostnameOverride               string
	PodInfraContainerImage         string
	DockerEndpoint                 string
	EtcdServerList                 util.StringList
	EtcdConfigFile                 string
	RootDirectory                  string
	AllowPrivileged                bool
	RegistryPullQPS                float64
	RegistryBurst                  int
	RunOnce                        bool
	EnableDebuggingHandlers        bool
	MinimumGCAge                   time.Duration
	MaxContainerCount              int
	AuthPath                       string
	CAdvisorPort                   uint
	OOMScoreAdj                    int
	APIServerList                  util.StringList
	ClusterDomain                  string
	MasterServiceNamespace         string
	ClusterDNS                     util.IP
	ReallyCrashForTesting          bool
	StreamingConnectionIdleTimeout time.Duration
}

// NewKubeletServer will create a new KubeletServer with default values.
func NewKubeletServer() *KubeletServer {
	return &KubeletServer{
		SyncFrequency:      10 * time.Second,
		FileCheckFrequency: 20 * time.Second,
		HTTPCheckFrequency: 20 * time.Second,
		EnableServer:       true,
		Address:            util.IP(net.ParseIP("127.0.0.1")),
		Port:               ports.KubeletPort,
		PodInfraContainerImage:  kubelet.PodInfraContainerImage,
		RootDirectory:           defaultRootDir,
		RegistryBurst:           10,
		EnableDebuggingHandlers: true,
		MinimumGCAge:            1 * time.Minute,
		MaxContainerCount:       5,
		CAdvisorPort:            4194,
		OOMScoreAdj:             -900,
		MasterServiceNamespace:  api.NamespaceDefault,
	}
}

// AddFlags adds flags for a specific KubeletServer to the specified FlagSet
func (s *KubeletServer) AddFlags(fs *pflag.FlagSet) {
	fs.StringVar(&s.Config, "config", s.Config, "Path to the config file or directory of files")
	fs.DurationVar(&s.SyncFrequency, "sync_frequency", s.SyncFrequency, "Max period between synchronizing running containers and config")
	fs.DurationVar(&s.FileCheckFrequency, "file_check_frequency", s.FileCheckFrequency, "Duration between checking config files for new data")
	fs.DurationVar(&s.HTTPCheckFrequency, "http_check_frequency", s.HTTPCheckFrequency, "Duration between checking http for new data")
	fs.StringVar(&s.ManifestURL, "manifest_url", s.ManifestURL, "URL for accessing the container manifest")
	fs.BoolVar(&s.EnableServer, "enable_server", s.EnableServer, "Enable the info server")
	fs.Var(&s.Address, "address", "The IP address for the info server to serve on (set to 0.0.0.0 for all interfaces)")
	fs.UintVar(&s.Port, "port", s.Port, "The port for the info server to serve on")
	fs.StringVar(&s.HostnameOverride, "hostname_override", s.HostnameOverride, "If non-empty, will use this string as identification instead of the actual hostname.")
	fs.StringVar(&s.PodInfraContainerImage, "pod_infra_container_image", s.PodInfraContainerImage, "The image whose network/ipc namespaces containers in each pod will use.")
	fs.StringVar(&s.DockerEndpoint, "docker_endpoint", s.DockerEndpoint, "If non-empty, use this for the docker endpoint to communicate with")
	fs.Var(&s.EtcdServerList, "etcd_servers", "List of etcd servers to watch (http://ip:port), comma separated. Mutually exclusive with -etcd_config")
	fs.StringVar(&s.EtcdConfigFile, "etcd_config", s.EtcdConfigFile, "The config file for the etcd client. Mutually exclusive with -etcd_servers")
	fs.StringVar(&s.RootDirectory, "root_dir", s.RootDirectory, "Directory path for managing kubelet files (volume mounts,etc).")
	fs.BoolVar(&s.AllowPrivileged, "allow_privileged", s.AllowPrivileged, "If true, allow containers to request privileged mode. [default=false]")
	fs.Float64Var(&s.RegistryPullQPS, "registry_qps", s.RegistryPullQPS, "If > 0, limit registry pull QPS to this value.  If 0, unlimited. [default=0.0]")
	fs.IntVar(&s.RegistryBurst, "registry_burst", s.RegistryBurst, "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")
	fs.BoolVar(&s.RunOnce, "runonce", s.RunOnce, "If true, exit after spawning pods from local manifests or remote urls. Exclusive with --etcd_servers, --api_servers, and --enable-server")
	fs.BoolVar(&s.EnableDebuggingHandlers, "enable_debugging_handlers", s.EnableDebuggingHandlers, "Enables server endpoints for log collection and local running of containers and commands")
	fs.DurationVar(&s.MinimumGCAge, "minimum_container_ttl_duration", s.MinimumGCAge, "Minimum age for a finished container before it is garbage collected.  Examples: '300ms', '10s' or '2h45m'")
	fs.IntVar(&s.MaxContainerCount, "maximum_dead_containers_per_container", s.MaxContainerCount, "Maximum number of old instances of a container to retain per container.  Each container takes up some disk space.  Default: 5.")
	fs.StringVar(&s.AuthPath, "auth_path", s.AuthPath, "Path to .kubernetes_auth file, specifying how to authenticate to API server.")
	fs.UintVar(&s.CAdvisorPort, "cadvisor_port", s.CAdvisorPort, "The port of the localhost cAdvisor endpoint")
	fs.IntVar(&s.OOMScoreAdj, "oom_score_adj", s.OOMScoreAdj, "The oom_score_adj value for kubelet process. Values must be within the range [-1000, 1000]")
	fs.Var(&s.APIServerList, "api_servers", "List of Kubernetes API servers for publishing events, and reading pods and services. (ip:port), comma separated.")
	fs.StringVar(&s.ClusterDomain, "cluster_domain", s.ClusterDomain, "Domain for this cluster.  If set, kubelet will configure all containers to search this domain in addition to the host's search domains")
	fs.StringVar(&s.MasterServiceNamespace, "master_service_namespace", s.MasterServiceNamespace, "The namespace from which the kubernetes master services should be injected into pods")
	fs.Var(&s.ClusterDNS, "cluster_dns", "IP address for a cluster DNS server.  If set, kubelet will configure all containers to use this for DNS resolution in addition to the host's DNS servers")
	fs.BoolVar(&s.ReallyCrashForTesting, "really_crash_for_testing", s.ReallyCrashForTesting, "If true, crash with panics more often.")
	fs.DurationVar(&s.StreamingConnectionIdleTimeout, "streaming_connection_idle_timeout", 0, "Maximum time a streaming connection can be idle before the connection is automatically closed.  Example: '5m'")
}

// Run runs the specified KubeletServer.  This should never exit.
func (s *KubeletServer) Run(_ []string) error {
	util.ReallyCrash = s.ReallyCrashForTesting
	rand.Seed(time.Now().UTC().UnixNano())

	// Cluster creation scripts support both kubernetes versions that 1)
	// support kublet watching apiserver for pods, and 2) ones that don't. So
	// they can set both --etcd_servers and --api_servers.  The current code
	// will ignore the --etcd_servers flag, while older kubelet code will use
	// the --etcd_servers flag for pods, and use --api_servers for event
	// publising.
	//
	// TODO(erictune): convert all cloud provider scripts and Google Container Engine to
	// use only --api_servers, then delete --etcd_servers flag and the resulting dead code.
	if len(s.EtcdServerList) > 0 && len(s.APIServerList) > 0 {
		glog.Infof("Both --etcd_servers and --api_servers are set.  Not using etcd source.")
		s.EtcdServerList = util.StringList{}
	}

	if err := util.ApplyOomScoreAdj(0, s.OOMScoreAdj); err != nil {
		glog.Info(err)
	}

	client, err := s.createAPIServerClient()
	if err != nil && len(s.APIServerList) > 0 {
		glog.Warningf("No API client: %v", err)
	}

	glog.Infof("Using root directory: %v", s.RootDirectory)

	credentialprovider.SetPreferredDockercfgPath(s.RootDirectory)

	kcfg := KubeletConfig{
		Address:                        s.Address,
		AllowPrivileged:                s.AllowPrivileged,
		HostnameOverride:               s.HostnameOverride,
		RootDirectory:                  s.RootDirectory,
		ConfigFile:                     s.Config,
		ManifestURL:                    s.ManifestURL,
		FileCheckFrequency:             s.FileCheckFrequency,
		HTTPCheckFrequency:             s.HTTPCheckFrequency,
		PodInfraContainerImage:         s.PodInfraContainerImage,
		SyncFrequency:                  s.SyncFrequency,
		RegistryPullQPS:                s.RegistryPullQPS,
		RegistryBurst:                  s.RegistryBurst,
		MinimumGCAge:                   s.MinimumGCAge,
		MaxContainerCount:              s.MaxContainerCount,
		ClusterDomain:                  s.ClusterDomain,
		ClusterDNS:                     s.ClusterDNS,
		Runonce:                        s.RunOnce,
		Port:                           s.Port,
		CAdvisorPort:                   s.CAdvisorPort,
		EnableServer:                   s.EnableServer,
		EnableDebuggingHandlers:        s.EnableDebuggingHandlers,
		DockerClient:                   dockertools.ConnectToDockerOrDie(s.DockerEndpoint),
		KubeClient:                     client,
		EtcdClient:                     kubelet.EtcdClientOrDie(s.EtcdServerList, s.EtcdConfigFile),
		MasterServiceNamespace:         s.MasterServiceNamespace,
		VolumePlugins:                  ProbeVolumePlugins(),
		StreamingConnectionIdleTimeout: s.StreamingConnectionIdleTimeout,
	}

	RunKubelet(&kcfg)

	// runs forever
	select {}

}

func (s *KubeletServer) setupRunOnce() {
	if s.RunOnce {
		// Don't use remote (etcd or apiserver) sources
		if len(s.EtcdServerList) > 0 {
			glog.Fatalf("invalid option: --runonce and --etcd_servers are mutually exclusive")
		}
		if len(s.APIServerList) > 0 {
			glog.Fatalf("invalid option: --runonce and --api_servers are mutually exclusive")
		}
		if s.EnableServer {
			glog.Infof("--runonce is set, disabling server")
			s.EnableServer = false
		}
	}
}

// TODO: replace this with clientcmd
func (s *KubeletServer) createAPIServerClient() (*client.Client, error) {
	authInfo, err := clientauth.LoadFromFile(s.AuthPath)
	if err != nil {
		glog.Warningf("Could not load kubernetes auth path: %v. Continuing with defaults.", err)
	}
	if authInfo == nil {
		// authInfo didn't load correctly - continue with defaults.
		authInfo = &clientauth.Info{}
	}
	clientConfig, err := authInfo.MergeWithConfig(client.Config{})
	if err != nil {
		return nil, err
	}
	if len(s.APIServerList) < 1 {
		return nil, fmt.Errorf("no api servers specified")
	}
	// TODO: adapt Kube client to support LB over several servers
	if len(s.APIServerList) > 1 {
		glog.Infof("Multiple api servers specified.  Picking first one")
	}
	clientConfig.Host = s.APIServerList[0]
	c, err := client.New(&clientConfig)
	if err != nil {
		return nil, err
	}
	return c, nil
}

// SimpleRunKubelet is a simple way to start a Kubelet talking to dockerEndpoint, using an etcdClient.
// Under the hood it calls RunKubelet (below)
func SimpleRunKubelet(client *client.Client,
	etcdClient tools.EtcdClient,
	dockerClient dockertools.DockerInterface,
	hostname, rootDir, manifestURL, address string,
	port uint,
	masterServiceNamespace string,
	volumePlugins []volume.Plugin) {
	kcfg := KubeletConfig{
		KubeClient:             client,
		EtcdClient:             etcdClient,
		DockerClient:           dockerClient,
		HostnameOverride:       hostname,
		RootDirectory:          rootDir,
		ManifestURL:            manifestURL,
		PodInfraContainerImage: kubelet.PodInfraContainerImage,
		Port:                    port,
		Address:                 util.IP(net.ParseIP(address)),
		EnableServer:            true,
		EnableDebuggingHandlers: true,
		SyncFrequency:           3 * time.Second,
		MinimumGCAge:            10 * time.Second,
		MaxContainerCount:       5,
		MasterServiceNamespace:  masterServiceNamespace,
		VolumePlugins:           volumePlugins,
	}
	RunKubelet(&kcfg)
}

// RunKubelet is responsible for setting up and running a kubelet.  It is used in three different applications:
//   1 Integration tests
//   2 Kubelet binary
//   3 Standalone 'kubernetes' binary
// Eventually, #2 will be replaced with instances of #3
func RunKubelet(kcfg *KubeletConfig) {
	kcfg.Hostname = util.GetHostname(kcfg.HostnameOverride)
	if kcfg.KubeClient != nil {
		kubelet.SetupEventSending(kcfg.KubeClient, kcfg.Hostname)
	} else {
		glog.Infof("No api server defined - no events will be sent.")
	}
	kubelet.SetupLogging()
	kubelet.SetupCapabilities(kcfg.AllowPrivileged)

	credentialprovider.SetPreferredDockercfgPath(kcfg.RootDirectory)

	podCfg := makePodSourceConfig(kcfg)
	k, err := createAndInitKubelet(kcfg, podCfg)
	if err != nil {
		glog.Errorf("Failed to create kubelet: %s", err)
		return
	}
	// process pods and exit.
	if kcfg.Runonce {
		if _, err := k.RunOnce(podCfg.Updates()); err != nil {
			glog.Errorf("--runonce failed: %v", err)
		}
	} else {
		startKubelet(k, podCfg, kcfg)
	}
}

func startKubelet(k *kubelet.Kubelet, podCfg *config.PodConfig, kc *KubeletConfig) {
	// start the kubelet
	go util.Forever(func() { k.Run(podCfg.Updates()) }, 0)

	// start the kubelet server
	if kc.EnableServer {
		go util.Forever(func() {
			kubelet.ListenAndServeKubeletServer(k, net.IP(kc.Address), kc.Port, kc.EnableDebuggingHandlers)
		}, 0)
	}
}

func makePodSourceConfig(kc *KubeletConfig) *config.PodConfig {
	// source of all configuration
	cfg := config.NewPodConfig(config.PodConfigNotificationSnapshotAndUpdates)

	// define file config source
	if kc.ConfigFile != "" {
		glog.Infof("Adding manifest file: %v", kc.ConfigFile)
		config.NewSourceFile(kc.ConfigFile, kc.FileCheckFrequency, cfg.Channel(kubelet.FileSource))
	}

	// define url config source
	if kc.ManifestURL != "" {
		glog.Infof("Adding manifest url: %v", kc.ManifestURL)
		config.NewSourceURL(kc.ManifestURL, kc.HTTPCheckFrequency, cfg.Channel(kubelet.HTTPSource))
	}
	if kc.EtcdClient != nil {
		glog.Infof("Watching for etcd configs at %v", kc.EtcdClient.GetCluster())
		config.NewSourceEtcd(config.EtcdKeyForHost(kc.Hostname), kc.EtcdClient, cfg.Channel(kubelet.EtcdSource))
	}
	if kc.KubeClient != nil {
		glog.Infof("Watching apiserver")
		config.NewSourceApiserver(kc.KubeClient, kc.Hostname, cfg.Channel(kubelet.ApiserverSource))
	}
	return cfg
}

// KubeletConfig is all of the parameters necessary for running a kubelet.
// TODO: This should probably be merged with KubeletServer.  The extra object is a consequence of refactoring.
type KubeletConfig struct {
	EtcdClient                     tools.EtcdClient
	KubeClient                     *client.Client
	DockerClient                   dockertools.DockerInterface
	CAdvisorPort                   uint
	Address                        util.IP
	AllowPrivileged                bool
	HostnameOverride               string
	RootDirectory                  string
	ConfigFile                     string
	ManifestURL                    string
	FileCheckFrequency             time.Duration
	HTTPCheckFrequency             time.Duration
	Hostname                       string
	PodInfraContainerImage         string
	SyncFrequency                  time.Duration
	RegistryPullQPS                float64
	RegistryBurst                  int
	MinimumGCAge                   time.Duration
	MaxContainerCount              int
	ClusterDomain                  string
	ClusterDNS                     util.IP
	EnableServer                   bool
	EnableDebuggingHandlers        bool
	Port                           uint
	Runonce                        bool
	MasterServiceNamespace         string
	VolumePlugins                  []volume.Plugin
	StreamingConnectionIdleTimeout time.Duration
}

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, err := kubelet.NewMainKubelet(
		kc.Hostname,
		kc.DockerClient,
		kc.EtcdClient,
		kc.KubeClient,
		kc.RootDirectory,
		kc.PodInfraContainerImage,
		kc.SyncFrequency,
		float32(kc.RegistryPullQPS),
		kc.RegistryBurst,
		kc.MinimumGCAge,
		kc.MaxContainerCount,
		pc.IsSourceSeen,
		kc.ClusterDomain,
		net.IP(kc.ClusterDNS),
		kc.MasterServiceNamespace,
		kc.VolumePlugins,
		kc.StreamingConnectionIdleTimeout)

	if err != nil {
		return nil, err
	}

	k.BirthCry()

	go k.GarbageCollectLoop()
	go kubelet.MonitorCAdvisor(k, kc.CAdvisorPort)

	return k, nil
}