Kubernetes | Any hooks available for Pod restarts? - kubernetes

Question

Are there any hooks available for Pod lifecycle events? Specifically, I want to run a command to upload logs on pod restart.

Answer 1

Edit: PreStop hook doesn't work for container restart - please see rest of answer below
As standing in documentation there are PreStop and PostStart events and you can attach to them.
Example from docs:
apiVersion: v1
kind: Pod
metadata:
name: lifecycle-demo
spec:
containers:
- name: lifecycle-demo-container
image: nginx
lifecycle:
postStart:
exec:
command: ["/bin/sh", "-c", "echo Hello from the postStart handler > /usr/share/message"]
preStop:
exec:
command: ["/bin/sh","-c","nginx -s quit; while killall -0 nginx; do sleep 1; done"]
Edit:
So I checked with following POC if that preStop hook is executed on container crash and conclusion is: NOT
apiVersion: v1
kind: Pod
metadata:
name: lifecycle-demo
spec:
containers:
- name: lifecycle-demo-container
volumeMounts:
- mountPath: /data
name: test-volume
image: nginx
command: ["/bin/sh"]
args: ["-c", "sleep 5; exit 1"]
lifecycle:
postStart:
exec:
command: ["/bin/sh", "-c", "echo Hello from the postStart handler > /data/postStart"]
preStop:
exec:
command: ["/bin/sh","-c","echo preStop handler! > /data/preStop"]
volumes:
- name: test-volume
hostPath:
path: /data
type: Directory
As solution for you I would recommend to override command section for you container this way:
command: ["/bin/sh"]
args: ["-c", "your-application-executable; your-logs-upload"]
so your-logs-upload executable will be executed after your-application-executable crash/end