How to fix Init:RunContainerError in Kubernetes

Check init container status:

kubectl describe pod <pod-name>

Look at the Init Containers section:
- State: Waiting, Running, or Terminated
- Reason: Why it failed
- Exit Code: 0 (success), 1 (error), 137 (OOMKilled)

Also check:

kubectl get pod <pod-name> -o jsonpath='{.status.initContainerStatuses}'

Get logs from the failed init container:

kubectl logs <pod-name> -c <init-container-name>

# If it crashed, get previous logs
kubectl logs <pod-name> -c <init-container-name> --previous

The init container name is defined in your pod spec under initContainers:. Logs reveal the actual error from the container.

Ensure the image exists and command is valid:

# Test the image locally
docker run --rm <init-image> <command>

# Check what command is configured
kubectl get pod <pod-name> -o yaml | grep -A 20 initContainers

Common issues:
- Image tag doesn't exist
- Command path is wrong
- Shell not available in image (use /bin/sh not /bin/bash for alpine)

Init containers MUST complete and exit. They cannot run indefinitely:

# Wrong - runs forever
initContainers:
- name: init
  image: busybox
  command: ["tail", "-f", "/dev/null"]

# Correct - exits after task
initContainers:
- name: init
  image: busybox
  command: ["sh", "-c", "until nslookup myservice; do sleep 2; done"]

If your init container is meant to wait for something, ensure it has an exit condition.

Exit code 137 means OOMKilled - increase memory:

initContainers:
- name: init-db
  image: postgres
  resources:
    limits:
      memory: "256Mi"
    requests:
      memory: "128Mi"

Note: Kubernetes reserves the highest resource request among all init containers (not sum), since they run sequentially.

Init containers often wait for services:

initContainers:
- name: wait-for-db
  image: busybox
  command: ['sh', '-c', 'until nc -z postgres-service 5432; do echo waiting; sleep 2; done']

Check:
- Service exists: kubectl get svc
- DNS resolves: kubectl run test --rm -it --image=busybox -- nslookup <service>
- Port is open: kubectl run test --rm -it --image=busybox -- nc -zv <service> <port>