Prestop hook

The semantics of Prestop are also very simple, and call before stopping.

But before what stops? Before the container stops? Before pod destruction?

The exact time of Prestop is called before Kubernetes sends top note to SIGTERM.
It should be noted that the SIGTERM signal is sent to the pod and the prestop hook is the container

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx
        lifecycle:
          preStop:
            exec:
              command:
              - sh
              - -c
              - sleep 30
      - name: u1
        command:
        - sleep
        - infinity
        image: ubuntu
        lifecycle:
          preStop:
            exec:
              command:
              - sh
              - -c
              - date "+%Y-%m-%d %H:%M:%S" >> /datetmp.txt && sleep 5
      - name: u2
        command:
        - sleep
        - infinity
        image: ubuntu
        lifecycle:
          preStop:
            exec:
              command:
              - sh
              - -c
              - date "+%Y-%m-%d %H:%M:%S" >> /datetmp.txt && sleep 10

In the script, nginx is blocked for 30 seconds, and finally it should be killed
There is a difference of 5 seconds between the blocking time of the two Ubuntu containers,
The observed result is that they all end together in the last 30 seconds, while the prestop script starts asynchronously at the same time