What is Kubernetes Ephemeral Storage?

Question

Accepted Answer

**Ephemeral Storage** — temporary storage for Pods.

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: app
    image: myapp:latest
    resources:
      limits:
        ephemeral-storage: "2Gi"
      requests:
        ephemeral-storage: "1Gi"
    volumeMounts:
    - name: cache
      mountPath: /cache
    - name: tmp
      mountPath: /tmp
  volumes:
  - name: cache
    emptyDir:
      sizeLimit: 500Mi
      medium: ""
  - name: tmp
    emptyDir:
      sizeLimit: 100Mi
---
# Ephemeral container storage
apiVersion: v1
kind: Pod
metadata:
  name: debug-pod
spec:
  containers:
  - name: app
    image: myapp:latest
  ephemeralContainers:
  - name: debugger
    image: busybox:1.36
    volumeMounts:
    - name: debug-storage
      mountPath: /debug
  volumes:
  - name: debug-storage
    emptyDir:
      sizeLimit: 1Gi
```

```bash
# Check ephemeral storage usage
kubectl top pod my-pod
kubectl describe pod my-pod | grep -A 5 "Ephemeral Storage"

# Check node ephemeral storage
kubectl describe node node-1 | grep -A 5 "Allocated resources"
kubectl top nodes

# Check emptyDir usage
kubectl exec my-pod -- df -h /cache
kubectl exec my-pod -- du -sh /cache/*

# Verify size limits
kubectl get pod my-pod -o jsonpath='{.spec.volumes}' | jq
```

**Storage Types:**
- emptyDir: empty directory (default).
- emptyDir with medium: Memory (tmpfs).
- ConfigMap/Secret projection.
- Ephemeral inline volumes.

**Eviction:**
- If usage > requests, Pod may be evicted.
- If usage > limits, Pod will be evicted.
- Eviction based on node pressure.

DevOps: What is Kubernetes Ephemeral Storage?