Kubernetes 0-1 使用preStop优雅终止Pod #

$ kubectl explain pod.spec.containers.lifecycle.preStop
KIND:     Pod
VERSION:  v1

RESOURCE: preStop <Object>

DESCRIPTION:
     PreStop is called immediately before a container is terminated due to an
     API request or management event such as liveness/startup probe failure,
     preemption, resource contention, etc. The handler is not called if the
     container crashes or exits. The reason for termination is passed to the
     handler. The Pod's termination grace period countdown begins before the
     PreStop hooked is executed. Regardless of the outcome of the handler, the
     container will eventually terminate within the Pod's termination grace
     period. Other management of the container blocks until the hook completes
     or until the termination grace period is reached. More info:
     https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks

     Handler defines a specific action that should be taken

FIELDS:
   exec <Object>
     One and only one of the following should be specified. Exec specifies the
     action to take.

   httpGet      <Object>
     HTTPGet specifies the http request to perform.

   tcpSocket    <Object>
     TCPSocket specifies an action involving a TCP port. TCP hooks not yet
     supported

$ kubectl explain pod.spec.containers.lifecycle.preStop.exec
KIND:     Pod
VERSION:  v1

RESOURCE: exec <Object>

DESCRIPTION:
...
FIELDS:
   command      <[]string>
     Command is the command line to execute inside the container, the working
     directory for the command is root ('/') in the container's filesystem. The
     command is simply exec'd, it is not run inside a shell, so traditional
     shell instructions ('|', etc) won't work. To use a shell, you need to
     explicitly call out to that shell. Exit status of 0 is treated as
     live/healthy and non-zero is unhealthy.

$ kubectl apply -f pod.yaml
# pod.yaml文件内容：
apiVersion: v1
kind: Pod
metadata:
  name: busybox
  namespace: default
spec:
  containers:
    - name: busybox
      image: busybox
      command: ["/bin/sh", "-c", "sleep 10m"]
      lifecycle:
        preStop:
          exec:
            command:
              [
                "/bin/sh",
                "-c",
                "echo this pod is stopping. > /stop.log && sleep 10s",
              ]

kubectl delete pod busybox

$ kubectl exec busybox -c busybox -- cat /stop.log
# 可以得到日志内容
this pod is stopping.