cri-o pod 创建源码分析
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))
}
