What is Kubernetes Pod Eviction Policy?

Question

Accepted Answer

**Eviction Policy** — control when Pods are evicted.

```yaml
# Node with eviction thresholds
apiVersion: v1
kind: Node
metadata:
  name: node-1
spec:
  unschedulable: false
---
# Pod with priority (higher = harder to evict)
apiVersion: v1
kind: Pod
metadata:
  name: critical-pod
spec:
  priorityClassName: critical
  containers:
  - name: app
    image: myapp:latest
    resources:
      requests:
        cpu: "1"
        memory: "2Gi"
      limits:
        cpu: "2"
        memory: "4Gi"
---
# PodDisruptionBudget
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: myapp-pdb
spec:
  minAvailable: 2
  selector:
    matchLabels:
      app: myapp
  unhealthyPodEvictionPolicy: AlwaysAllow
```

```bash
# Check eviction events
kubectl get events --field-selector reason=Evicted --sort-by=.lastTimestamp

# Check node conditions
kubectl get nodes -o custom-columns=NAME:.metadata.name,MEMORY_PRESSURE:.status.conditions[?(@.type=="MemoryPressure")].status,DISK_PRESSURE:.status.conditions[?(@.type=="DiskPressure")].status,PID_PRESSURE:.status.conditions[?(@.type=="PIDPressure")].status

# Check eviction thresholds
kubectl describe node node-1 | grep -A 10 "Allocated resources"

# Check Pod priority
kubectl get pods --sort-by=.spec.priority -A

# Check PDB status
kubectl get pdb
kubectl describe pdb myapp-pdb

# View evicted Pods
kubectl get pods --field-selector status.phase=Failed -A | grep Evicted
```

**Eviction Types:**
- Node pressure: memory/disk/PID exhaustion.
- Voluntary: drain, delete, scaling.
- Involuntary: OOM kill, node failure.

**Eviction Priority:**
- BestEffort (first).
- Burstable (memory usage > requests).
- Guaranteed (last).

DevOps: What is Kubernetes Pod Eviction Policy?