What is Kubernetes Ephemeral Containers?

Question

Accepted Answer

**Ephemeral Containers** — debug containers injected into running Pods.

```bash
# Add debug container to running Pod
kubectl debug -it my-pod --image=busybox:1.36 --target=app

# Debug with custom profile
kubectl debug -it my-pod \
  --image=nicolaka/netshoot \
  --target=app \
  -- /bin/bash

# Debug node (use ephemeral container on node)
kubectl debug node/node-1 -it --image=busybox:1.36

# Add ephemeral container via patch
kubectl patch pod my-pod -p '{"spec":{"ephemeralContainers":[{
  "name":"debugger",
  "image":"busybox:1.36",
  "stdin":true,
  "tty":true
}]}}'

# Attach to ephemeral container
kubectl attach -it my-pod -c debugger

# Copy from ephemeral container
kubectl cp my-pod:/app/logs/error.log ./error.log -c debugger

# Remove ephemeral container (not supported - Pod must be recreated)
```

```yaml
# Pod with ephemeral container in spec
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: app
    image: myapp:latest
  ephemeralContainers:
  - name: debugger
    image: busybox:1.36
    stdin: true
    tty: true
    targetNamespace: ""
```

**Use cases:**
- Debug production issues without restart.
- Inspect running processes.
- Network debugging (tcpdump, curl).
- File inspection.

DevOps: What is Kubernetes Ephemeral Containers?