Kubernetes 上如何控制容器的启动顺序？

apiVersion: apps/v1
kind: Deployment
metadata:
  creationTimestamp: null
  labels:
    app: sample
  name: sample
spec:
  replicas: 1
  selector:
    matchLabels:
      app: sample
  strategy: {}
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: sample
    spec:
      containers:
      - image: addozhang/k8s-container-sequence-sidecar:latest
        name: sidecar
        imagePullPolicy: IfNotPresent
        lifecycle:
          postStart:
            exec:
              command:
                - /entrypoint
                - wait
      - image: busybox:latest
        name: app
        imagePullPolicy: IfNotPresent
        command: ["/bin/sh","-c"]
        args: ["date; echo 'app container started'; tail -f /dev/null"]

// SyncPod syncs the running pod into the desired pod by executing following steps:
//
//  1. Compute sandbox and container changes.
//  2. Kill pod sandbox if necessary.
//  3. Kill any containers that should not be running.
//  4. Create sandbox if necessary.
//  5. Create ephemeral containers.
//  6. Create init containers.
//  7. Create normal containers.
func (m *kubeGenericRuntimeManager) SyncPod(pod *v1.Pod, podStatus *kubecontainer.PodStatus, pullSecrets []v1.Secret, backOff *flowcontrol.Backoff) (result kubecontainer.PodSyncResult) {
    
    ...
    
  // Step 7: start containers in podContainerChanges.ContainersToStart.
  for _, idx := range podContainerChanges.ContainersToStart {
    start("container", containerStartSpec(&pod.Spec.Containers[idx]))
  }

  return
}

// startContainer starts a container and returns a message indicates why it is failed on error.
// It starts the container through the following steps:
// * pull the image
// * create the container
// * start the container
// * run the post start lifecycle hooks (if applicable)
func (m *kubeGenericRuntimeManager) startContainer(podSandboxID string, podSandboxConfig *runtimeapi.PodSandboxConfig, spec *startSpec, pod *v1.Pod, podStatus *kubecontainer.PodStatus, pullSecrets []v1.Secret, podIP string, podIPs []string) (string, error) {
     
     ...
     
  // Step 4: execute the post start hook.
  if container.Lifecycle != nil && container.Lifecycle.PostStart != nil {
    kubeContainerID := kubecontainer.ContainerID{
      Type: m.runtimeName,
      ID:   containerID,
    }
    msg, handlerErr := m.runner.Run(kubeContainerID, pod, container, container.Lifecycle.PostStart)
    if handlerErr != nil {
      m.recordContainerEvent(pod, container, kubeContainerID.ID, v1.EventTypeWarning, events.FailedPostStartHook, msg)
      if err := m.killContainer(pod, kubeContainerID, container.Name, "FailedPostStartHook", reasonFailedPostStartHook, nil); err != nil {
        klog.ErrorS(fmt.Errorf("%s: %v", ErrPostStartHook, handlerErr), "Failed to kill container", "pod", klog.KObj(pod),
          "podUID", pod.UID, "containerName", container.Name, "containerID", kubeContainerID.String())
      }
      return msg, fmt.Errorf("%s: %v", ErrPostStartHook, handlerErr)
    }
  }

  return "", nil
}

for time.Now().Before(timeoutAt) {
  err = checkIfReady(client, url)
  if err == nil {
    log.Println("sidecar is ready")
    return nil
  }
  log.Println("sidecar is not ready")
  time.Sleep(time.Duration(periodMillis) * time.Millisecond)
}
return fmt.Errorf("sidecar is not ready in %d second(s)", timeoutSeconds)