「连载」边缘计算(十七)02-20:边缘部分源码(源码分析篇)

(接上篇)

EdgeCore之edged

下面对EdgeCore组件进行剖析,因为EdgeCore中的功能组件比较多,共包括devicetwin、edged、edgehubeventbusedgemeshmetamanagerservicebus和test共8个功能模块。限于篇幅,本文只对edged的具体逻辑以及edged调用容器运行时进行剖析。

1.edged的具体逻辑剖析

EdgeCore模块注册函数入手,具体如下所示。

KubeEdge/edge/cmd/EdgeCore/app/server.go

// registerModules register all the modules started in EdgeCore

func registerModules() {

...

edged.Register()

...

}

进入registerModules()函数中的edged.Register(),具体如下所示。

KubeEdge/edge/pkg/edged/edged.go

// Register register edged

func Register() {

edged, err := newEdged()

if err != nil {

klog.Errorf("init new edged error, %v", err)

return

}

core.Register(edged)

}

Register()函数中主要做了如下两件事:

1)初始化edged(edged, err := newEdged());

2)注册将已经实例化的edged struct(core.Register(edged))。

下面深入剖析初始化edged过程中具体做了哪些事情。进入newEdged()函数,具体内容如下所示。

KubeEdge/edge/pkg/edged/edged.go

//newEdged creates new edged object and initialises it

func newEdged() (*edged, error) {

conf := getConfig()

backoff := flowcontrol.NewBackOff(backOffPeriod, MaxContainerBackOff)

podManager := podmanager.NewpodManager()

policy := images.ImageGCPolicy{

...

}

// build new object to match interface

recorder := record.NewEventRecorder()

ed := &edged{

...

}

...

ed.livenessManager = proberesults.NewManager()

...

statsProvider := edgeimages.NewStatsProvider()

...

//create and start the docker shim running as a grpc server

if conf.remoteRuntimeEndpoint == dockerShimEndpoint || conf.remoteRuntimeEndpoint == dockerShimEndpointDeprecated {

streamingConfig := &streaming.Config{}

dockerClientConfig := &dockershim.ClientConfig{

dockerEndpoint:            conf.dockerAddress,

ImagePullProgressDeadline: time.Duration(conf.imagePullProgressDeadline) * time.Second,

EnableSleep:               true,

WithTraceDisabled:         true,

}

pluginConfigs := dockershim.NetworkPluginSettings{

...

}

...

ds, err := dockershim.NewdockerService(dockerClientConfig, conf.podSandboxImage, streamingConfig,

&pluginConfigs, cgroupName, cgroupDriver, dockershimRootDir, redirectContainerStream)

if err != nil {

return nil, err

}

klog.Infof("RemoteRuntimeEndpoint: %q, remoteImageEndpoint: %q",

conf.remoteRuntimeEndpoint, conf.remoteRuntimeEndpoint)

klog.Info("Starting the GRPC server for the docker CRI shim.")

server := dockerremote.NewdockerServer(conf.remoteRuntimeEndpoint, ds)

if err := server.Start(); err != nil {

return nil, err

}

}

ed.clusterDNS = convertStrToIP(conf.clusterDNS)

ed.dnsConfigurer = kubedns.NewConfigurer(recorder, nodeRef, ed.nodeIP, ed.clusterDNS, conf.clusterDomain, ResolvConfDefault)

containerRefManager := kubecontainer.NewRefManager()

httpClient := &http.Client{}

runtimeService, imageService, err := getRuntimeAndImageServices(conf.remoteRuntimeEndpoint, conf.remoteRuntimeEndpoint, conf.RuntimeRequestTimeout)

if err != nil {

return nil, err

}

if ed.os == nil {

ed.os = kubecontainer.RealOS{}

}

ed.clcm, err = clcm.NewContainerLifecycleManager(DefaultRootDir)

var machineInfo cadvisorapi.MachineInfo

machineInfo.MemoryCapacity = uint64(conf.memoryCapacity)

containerRuntime, err := kuberuntime.NewKubeGenericRuntimeManager(

...

)

cadvisorInterface, err := cadvisor.New("")

containerManager, err := cm.NewContainerManager(mount.New(""),

cadvisorInterface,

cm.NodeConfig{

...

},

false,

conf.devicePluginEnabled,

recorder)

ed.containerRuntime = containerRuntime

ed.containerRuntimeName = RemoteContainerRuntime

ed.containerManager = containerManager

ed.runtimeService = runtimeService

imageGCManager, err := images.NewImageGCManager(ed.containerRuntime, statsProvider, recorder, nodeRef, policy, conf.podSandboxImage)

...

ed.imageGCManager = imageGCManager

containerGCManager, err := kubecontainer.NewContainerGC(containerRuntime, containerGCPolicy, &containers.KubeSourcesReady{})

...

ed.containerGCManager = containerGCManager

ed.server = server.NewServer(ed.podManager)

ed.volumePluginMgr, err = NewInitializedVolumePluginMgr(ed, ProbeVolumePlugins(""))

...

return ed, nil

}

newEdged()函数的定义中,我们可以知道其做很多事情,具体如下。

1)获取edged相关配置(conf := getConfig());

2)初始化podmanagerpodManager := podmanager.NewpodManager());

3)初始化edged struct(ed := &edged{});

4)初始化 edged的livenessManager

5)初始化edged的镜像存放地;

6)创建并启动dockershimgrpc server;

7) 初始化运行时服务和镜像服务;

8)初始化通用容器运行时服务;

9)初始化镜像垃圾回收管理器;

10)初始化容器垃圾回收器;

11)初始化edged的server;

12)初始化edged的volume plugin管理器。

针对以上动作,笔者重点分析创建并启动dockershimgrpc server。dockershim是edged与容器运行时交互的管道,所以edged对容器操作在dockershim的方法中都会得到体现。dockershim服务的初始化函数定义具体如下所示。

 「未完待续……

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