How to fix Exit Code 128 in Kubernetes

Get detailed error information:

kubectl describe pod <pod-name>

Look for the Last State section and Events. Common messages include:
- "ContainerCannotRun" - command startup failure
- "StartError: failed to create containerd task" - runtime issue
- "executable file not found in $PATH" - missing binary

Test the image locally:

# Check if command exists
docker run --rm <image>:<tag> which <command>

# List what's in the expected path
docker run --rm <image>:<tag> ls -la /app/

# Try running the exact command
docker run --rm <image>:<tag> <your-command>

If the command doesn't exist, fix your Dockerfile to include it.

Exit code 128 can occur when volumes fail to mount:

kubectl describe pod <pod-name> | grep -A 10 "Volumes:"
kubectl get pvc  # Check PersistentVolumeClaim status

Common issues:
- ConfigMap modified while pod is starting
- PVC not bound to a PV
- NFS or cloud storage mount failures

Avoid editing ConfigMaps during pod startup. Use immutable ConfigMaps for critical configs.

If your entrypoint script uses invalid exit values:

# Wrong - exit code must be 0-255
exit 256  # Results in exit code 0
exit -1   # Results in exit code 255

# Correct
exit 1    # Valid error code
exit 0    # Success

Review your scripts for any dynamic exit codes that might exceed 255.

The container user may lack permission to execute:

securityContext:
  runAsUser: 1000
  runAsNonRoot: true

Ensure:
1. The binary has execute permissions for that user
2. SecurityContext doesn't block execution
3. No SELinux/AppArmor policies preventing startup

Test locally with the same user:

docker run --user 1000 <image> <command>

If the container won't start, override to debug:

command: ["/bin/sh", "-c", "sleep infinity"]

Then exec in and investigate:

kubectl exec -it <pod-name> -- /bin/sh

# Check if command exists
which mycommand
ls -la /app/entrypoint.sh

# Try running manually
/app/entrypoint.sh