cri-o pod 创建源码分析

时间:2023-01-07 17:58:47

1、 server/sandbox.go

// RunPodSandbox creates and runs a pod-level sandbox

func (s *Server) RunPodSandbox(ctx context.Context, req *pb.RunPodSandboxRequest) (*pb.RunPodSandboxResponse, error)

  name := req.GetConfig().GetMetadata().GetName()

  namespace := req.GetConfig().GetMetadata().GetNamespace() //在test中,该字段为空

  attempt := req.GetConfig().GetMetadata().GetAttempt() //在test中,该字段为空

  id, name, err := s.generatePodIDandName(name,  namespace, attempt)

  podSandboxDir := filepath.Join(s.sandbox, id)

  os.MkdirAll(podSandboxDir, 0755)

  ... // defer函数,用于创建pod失败,移除podSandboxDir

  // creates a spec Generator with the default spec

  g := generate.New()  // 返回一个Generator结构,其中包含了默认的spec

  podInfraRootfs := filepath.Join(s.root, "graph/vfs/pause")

  g.SetRootPath(filepath.Join(podInfraRootfs, "rootfs"))  //对默认的spec进行修改,针对的字段为Root和Process.Args

  g.SetRootReadonly(true)

  g.SetProcessArgs([]string{"/pause"})

  ... // 设置g.spec的hostname,如果req.config中的hostname 不为空的话

  // set log directory

  logDir := req.GetConfig().GetLogDirectory() // test的config文件默认为"."

  if logDir == "" {

    logDir = fmt.Sprintf("/var/log/ocid/pods/%s", id)

  }  

  // set DNS options

  ... // 从req.Config中获取dnsServers和dnsSearches

  resolvPat := fmt.Sprintf("%s/resolv.conf", podSandboxDir)

  parseDNSOptions(dnsServers, dnsSearches, resolvPath)

  // add labels

  labels := req.GetConfig().GetLabels()

  labelsJSON, err := json.Marshal(labels)  

  // add annotations

  annotations := req.GetConfig().GetAnnotations()
  annotationsJSON, err := json.Marshal(annotations)

  // Don't use SELinux separation with Host Pid or IPC Namespace

  if !req.GetConfig.GetLinux().GetNamespaceOptions().GetHostPid() && !req.GetConfig().GetLinux().GetNamespaceOptions().GetHostIpc() {

    processLabel, mountLabel, err = getSELinuxLabels(nil)

    g.SetProcessSelinuxLabel(processLabel)

  }

  containerID, containerName, err :=  s.generateContainerIDandName(name, "infra", 0)

  g.AddAnnotation("ocid/labels", string(labelsJSON))

  ... // add annotation "ocid/annotations", "ocid/log_path", "ocid/name", "ocid/container_name", "ocid/container_id"

  s.addSandbox(&sandbox{

    id:    id,

    ....

    containers:  oci.NewMemoryStore(),

    ...

    metadata:  req.GetConfig().GetMetadata(),

  })

  for k, v := range annotations {

    g.AddAnnotation(k, v)
  }

  ...  // setup cgroup settings, setup namespaces

  err = g.SaveToFile(filepath.Join(podSandboxDir, "config.json"))

  if _, err = os.stat(podInfraRootfs); err != nil {

    if os.IsNotExist(err) {

      utils.CreateInfraRootfs(podInfraRootfs, s.pausePath) // podInfraRootfs is /var/lib/ocid/graph/vfs/pause

      // copying infra rootfs binary: /usr/libexec/ocid/pause -> /var/lib/ocid/graph/vfs/pause/rootfs/pause
    }

  }

  container, err := oci.NewContainer(containerID, containerName, podSandboxDir, podSanboxDir, labels, id, false) // bundlePath 也是podSandboxDir

  s.runtime.CreateContainer(container)

  s.runtime.UpdateStatus(container)

  // setup the network

  podNamespace := ""

  netnsPath, err := container.NetNsPath()

  s.netPlugin.SetUpPod(netnsPath, podNamespace, id, containerName)

  s.runtime.StartContainer(container)

  s.addContainer(container)

  s.podIDIndex.Add(id)

  s.runtime.UpdateStatus(container)

  return &pb.RunSandboxResponse{PodSandboxId: &id}, nil

2、 oci/oci.go

// 该函数主要用于创建容器,并且同步等待返回容器的pid

func (r *Runtime) CreateContainer(c *Container) error

  parentPipe, childPipe, err := newPipe()

  defer parentPipe.Close()

  args := []string{"-c", c.name}

  args = append(args, "-r", r.path)

  if c.terminal { args = append(args, "-t")}

  cmd := exec.Command(r.conmonPath, args...)

  cms.Dir = c.bundlePath

  cmd.SysProcAttr = &syscall.SysProcAttr{ Setpgid: true, }

  cmd.Stdin = os.Stdin

  cmd.Stdout = os.Stdout

  cmd.Stderr = os.Stderr

  cmd.ExtraFiles = append(cmd.ExtraFiles, childPipe)

  cmd.Env = append(cmd.Env, fmt.Sprintf("_OCI_SYNCPIPE=%d", 3))

  err = cmd.Start()

  childPipe.Close()

  // Wait to get container pid from conmon

  var si *syncInfo

  json.NewDecoder(parentPipe).Decode(&si)

  logrus.Infof("Received container pid: %v", si.Pid)

  return nil

3、 oci/oci.go

func (r *Runtime) UpdateStatus(c *Container) error

  ...

  out, err := exec.Command(r.path, "state", c.name).Output()

  stateReader := bytes.NewReader(out)

  json.NewDecoder(stateReader).Decode(&c.state)

  if c.state.Status == ContainerStateStopped {

    exitFilePath := filepath.Join(c.bundlePath, "exit")

    fi, err := os.Stat(exitFilePath)

    st := fi.Sys().(*syscall.Stat_t)

    c.state.Finished = time.Unix(st.Ctim.Sec, st.Ctim.Nsec)

    statusCodeStr, err := ioutil.ReadFile(exitFilePath)

    statusCode, err := strconv.Atoi(string(statusCodeStr))

    c.state.ExitCode = int32(utils.StatusToExitCode(statusCode))

  }