kubernetes Sandbox删除详解

上一篇blog讲解了一下gc的整个流程。后面介绍了删除sandbox。但sandbox怎么删除还是没有讲清楚，在此详细展开说一下,通过sandbox id去删除sandbox代码在pkg/kubelet/kuberuntime/kuberuntime_gc.go。

func (cgc *containerGC) removeSandbox(sandboxID string) {    glog.V(4).Infof("Removing sandbox %q", sandboxID)    // In normal cases, kubelet should've already called StopPodSandbox before    // GC kicks in. To guard against the rare cases where this is not true, try    // stopping the sandbox before removing it.    if err := cgc.client.StopPodSandbox(sandboxID); err != nil {        glog.Errorf("Failed to stop sandbox %q before removing: %v", sandboxID, err)        return    }    if err := cgc.client.RemovePodSandbox(sandboxID); err != nil {        glog.Errorf("Failed to remove sandbox %q: %v", sandboxID, err)    }}

上面的代码分为两步，第一步是停止sandbox，第二步是删除sandbox。
先看停止pkg/kubelet/dockershim/docker_sandbox.go。

func (ds *dockerService) StopPodSandbox(podSandboxID string) error {...    errList := []error{}    if needNetworkTearDown {        cID := kubecontainer.BuildContainerID(runtimeName, podSandboxID)        err := ds.network.TearDownPod(namespace, name, cID)        if err == nil {            ds.setNetworkReady(podSandboxID, false)        } else {            errList = append(errList, err)        }    }    if err := ds.client.StopContainer(podSandboxID, defaultSandboxGracePeriod); err != nil {        glog.Errorf("Failed to stop sandbox %q: %v", podSandboxID, err)        // Do not return error if the container does not exist        if !libdocker.IsContainerNotFoundError(err) {            errList = append(errList, err)        }    }...

先调用cni去删除网络，然后采集是停止容器。
先看删除网络调用cni的过程

err := ds.network.TearDownPod(namespace, name, cID)

具体实现在pkg/kubelet/network/cni/cni.go

func (plugin *cniNetworkPlugin) TearDownPod(namespace string, name string, id kubecontainer.ContainerID) error {    if err := plugin.checkInitialized(); err != nil {        return err    }    // Lack of namespace should not be fatal on teardown    netnsPath, err := plugin.host.GetNetNS(id.ID)    if err != nil {        glog.Warningf("CNI failed to retrieve network namespace path: %v", err)    }    return plugin.deleteFromNetwork(plugin.getDefaultNetwork(), name, namespace, id, netnsPath)}

再深入看看上面删除网络方法deleteFromNetwork

func (plugin *cniNetworkPlugin) deleteFromNetwork(network *cniNetwork, podName string, podNamespace string, podInfraContainerID kubecontainer.ContainerID, podNetnsPath string) error {    rt, err := plugin.buildCNIRuntimeConf(podName, podNamespace, podInfraContainerID, podNetnsPath)    if err != nil {        glog.Errorf("Error deleting network when building cni runtime conf: %v", err)        return err    }    netConf, cniNet := network.NetworkConfig, network.CNIConfig    glog.V(4).Infof("About to del CNI network %v (type=%v)", netConf.Name, netConf.Plugins[0].Network.Type)    err = cniNet.DelNetworkList(netConf, rt)    if err != nil {        glog.Errorf("Error deleting network: %v", err)        return err    }    return nil}

先是装配参数netConf和rt，然后是通过DelNetworkList是删除，
继续看代码DelNetworkList

func (c *CNIConfig) DelNetworkList(list *NetworkConfigList, rt *RuntimeConf) error {    for i := len(list.Plugins) - 1; i >= 0; i-- {        net := list.Plugins[i]        pluginPath, err := invoke.FindInPath(net.Network.Type, c.Path)        if err != nil {            return err        }        newConf, err := buildOneConfig(list, net, nil, rt)        if err != nil {            return err        }        if err := invoke.ExecPluginWithoutResult(pluginPath, newConf.Bytes, c.args("DEL", rt)); err != nil {            return err        }    }    return nil}

好了这里开始调用正在的/opt/cni/bin下面cni的二进制文件的地方，上面的pluginPath默认就是/opt/cni/bin，上面执行的DEL方法，这个如果大家感兴趣可以看看我之前CNI解析的blog。
如果大家对怎么执行二进制cni感兴趣，我再多说一句怎么执行cni的
vendor/github.com/containernetworking/cni/pkg/invoke/raw_exec.go

func (e *RawExec) ExecPlugin(pluginPath string, stdinData []byte, environ []string) ([]byte, error) {    stdout := &bytes.Buffer{}    c := exec.Cmd{        Env:    environ,        Path:   pluginPath,        Args:   []string{pluginPath},        Stdin:  bytes.NewBuffer(stdinData),        Stdout: stdout,        Stderr: e.Stderr,    }    if err := c.Run(); err != nil {        return nil, pluginErr(err, stdout.Bytes())    }    return stdout.Bytes(), nil}

通过golang 的os/exec去执行。