How to fix Exit Code 0 in Kubernetes

Ask: Should this container run continuously or complete and exit?

Long-running services (web servers, APIs, workers):
- Should use Deployment, StatefulSet, or DaemonSet
- Container must run a persistent foreground process
- Process should handle SIGTERM for graceful shutdown

Batch tasks (scripts, migrations, one-time jobs):
- Should use Job or CronJob resources
- Expected to complete and exit with code 0
- Kubernetes won't restart completed Jobs

If your container should run once and complete, use a Job:

apiVersion: batch/v1
kind: Job
metadata:
  name: my-batch-job
spec:
  template:
    spec:
      containers:
      - name: worker
        image: my-image:latest
        command: ["./run-migration.sh"]
      restartPolicy: OnFailure  # or Never
  backoffLimit: 3

Jobs expect containers to exit. Exit code 0 = success, no restart.

For setup steps that run before your main application:

spec:
  initContainers:
  - name: setup
    image: my-setup-image
    command: ["./init.sh"]  # Runs once, exits with 0
  containers:
  - name: app
    image: my-app-image
    command: ["./start-server.sh"]  # Long-running

Init containers run to completion before the main container starts. Exit code 0 from init containers is expected and doesn't cause restarts.

For Deployments, the container must run continuously:

# Wrong - script completes and exits
CMD ["./setup.sh"]

# Correct - exec into long-running process
CMD ["./setup.sh", "&&", "exec", "python", "server.py"]

Or in your shell script:

#!/bin/bash
./setup.sh
exec python server.py  # exec replaces shell with server process

The last command must be a process that runs until terminated.

If you need the container to stay running without a real service (for debugging):

command: ["tail", "-f", "/dev/null"]
# or
command: ["sleep", "infinity"]

This keeps the container alive so you can exec into it. Not recommended for production—use proper service processes instead.

Deployment defaults to restartPolicy: Always, which cannot be changed. For different policies:

# Jobs allow OnFailure or Never
restartPolicy: OnFailure  # Restart only if exit code != 0
restartPolicy: Never      # Never restart, even on failure

If you need restartPolicy other than Always for a pod, you cannot use Deployment—use a bare Pod or Job instead.