What is an appropriate Kubernetes livenessProbe command for a background process?
We have a NodeJS process that consumes messages off an SQS queue. Since it's a background job we don't expose any HTTP endpoints and so a liveness command seems to be the more appropriate way to do the liveness check. What would a "good enough" command setup look like that actually checks the process is alive and running properly? Should the NodeJS process touch a file to update its editted time and the liveness check validate that? Examples I've seen online seem disconnected to the actual process, e.g. they check a file exists.
You could use liveness using exec command.
Here is an example:
apiVersion: v1
kind: Pod
metadata:
labels:
test: liveness
name: liveness-exec
spec:
containers:
- name: liveness
image: k8s.gcr.io/busybox
args:
- /bin/sh
- -c
- touch /tmp/healthy; sleep 30; rm -rf /tmp/healthy; sleep 600
livenessProbe:
exec:
command:
- cat
- /tmp/healthy
initialDelaySeconds: 5
periodSeconds: 5To perform a probe, the kubelet executes the command cat /tmp/healthy in the target container. If the command succeeds, it returns 0, and the kubelet considers the container to be alive and healthy. If the command returns a non-zero value, the kubelet kills the container and restarts it.