「连载」边缘计算（十八）02-21：边缘部分源码（源码分析篇）

（接上篇）

k8s.io/Kubernetes/pkg/Kubelet/dockershim/docker_service.go

// NewdockerService creates a new `dockerService` struct. // NOTE: Anything passed to dockerService should be eventually handled in another way when we switch to running the shim as a different process. func NewdockerService(config *ClientConfig, podSandboxImage string, streamingConfig *streaming.Config, pluginSettings *NetworkPluginSettings, cgroupsName string, kubeCgroupDriver string, dockershimRootDir string, startLocalStreamingServer bool) (dockerService, error) { ... ds := &dockerService{ client:          c, os:              kubecontainer.RealOS{}, podSandboxImage: podSandboxImage, streamingRuntime: &streamingRuntime{ client:      client, execHandler: &NativeExecHandler{}, }, containerManager:          cm.NewContainerManager(cgroupsName, client), checkpointManager:         checkpointManager, startLocalStreamingServer: startLocalStreamingServer, networkReady:              make(map[string]bool), containerCleanupInfos:     make(map[string]*containerCleanupInfo), } ... }

从 NewdockerService()函数可以看出，dockershim的真身是dockerService struct。dockerService struct定义具体如下所示。

k8s.io/Kubernetes/pkg/Kubelet/dockershim/docker_service.go

type dockerService struct { client           libdocker.Interface os               kubecontainer.OSInterface podSandboxImage  string streamingRuntime *streamingRuntime streamingServer  streaming.Server network *network.PluginManager // Map of podSandboxID :: network-is-ready networkReady     map[string]bool networkReadyLock sync.Mutex containerManager cm.ContainerManager // cgroup driver used by docker runtime. cgroupDriver      string checkpointManager checkpointmanager.CheckpointManager // caches the version of the runtime. // To be compatible with multiple docker versions, we need to perform // version checking for some operations. Use this cache to avoid querying // the docker daemon every time we need to do such checks. versionCache *cache.ObjectCache // startLocalStreamingServer indicates whether dockershim should start a // streaming server on localhost. startLocalStreamingServer bool // containerCleanupInfos maps container IDs to the `containerCleanupInfo` structs // needed to clean up after containers have been started or removed. // (see `applyPlatformSpecificdockerConfig` and `performPlatformSpecificContainerCleanup` // methods for more info). containerCleanupInfos map[string]*containerCleanupInfo }

从dockerService的定义可以看出，大部分属性都是与container、pod、image相关的。我们从这些属性可以推测dockerService是与container runtime交互的一个组件。为了进一步验证猜想，可以在同一个文件中（k8s.io/Kubernetes/pkg/Kubelet/dockershim/docker_service.go）查看dockerService实现的方法。

以上只是剖析了edged的初始化过程。下面剖析edged的启动过程，具体如下所示。

KubeEdge/edge/pkg/edged/edged.go

func (e *edged) Start(c *context.Context) { e.context = c e.metaClient = client.New(c) // use self defined client to replace fake kube client e.kubeClient = fakekube.NewSimpleClientset(e.metaClient) e.statusManager = status.NewManager(e.kubeClient, e.podManager, utilpod.NewpodDeleteSafety(), e.metaClient) if err := e.initializeModules(); err != nil { klog.Errorf("initialize module error: %v", err) os.Exit(1) } e.volumeManager = volumemanager.NewVolumeManager( ... ) go e.volumeManager.Run(edgedutil.NewSourcesReady(), utilwait.NeverStop) go utilwait.Until(e.syncNodeStatus, e.nodeStatusUpdateFrequency, utilwait.NeverStop) e.probeManager = prober.NewManager(e.statusManager, e.livenessManager, containers.NewContainerRunner(), kubecontainer.NewRefManager(), record.NewEventRecorder()) e.pleg = edgepleg.NewGenericLifecycleRemote(e.containerRuntime, e.probeManager, plegChannelCapacity, plegRelistPeriod, e.podManager, e.statusManager, e.podCache, clock.RealClock{}, e.interfaceName) e.statusManager.Start() e.pleg.Start() e.podAddWorkerRun(concurrentConsumers) e.podRemoveWorkerRun(concurrentConsumers) housekeepingTicker := time.NewTicker(housekeepingPeriod) syncWorkQueueCh := time.NewTicker(syncWorkQueuePeriod) e.probeManager.Start() go e.syncLoopIteration(e.pleg.Watch(), housekeepingTicker.C, syncWorkQueueCh.C) go e.server.ListenAndServe() e.imageGCManager.Start() e.StartGarbageCollection() e.pluginManager = pluginmanager.NewPluginManager( ... ) // Adding Registration Callback function for CSI Driver e.pluginManager.AddHandler(pluginwatcherapi.CSIPlugin, plugincache.PluginHandler(csiplugin.PluginHandler)) // Start the plugin manager go e.pluginManager.Run(edgedutil.NewSourcesReady(), utilwait.NeverStop) e.syncpod() }

 「未完待续……」