What is Pod Disruption Budget?

Question

Accepted Answer

**Pod Disruption Budget (PDB)** guarantees a minimum number of running Pods during planned disruptions.

```yaml
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: myapp-pdb
  namespace: production
spec:
  minAvailable: 2
  selector:
    matchLabels:
      app: myapp
```

**Alternative with maxUnavailable:**
```yaml
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: myapp-pdb
spec:
  maxUnavailable: 1
  selector:
    matchLabels:
      app: myapp
```

**minAvailable vs maxUnavailable:**
- `minAvailable: 3` — always at least 3 Pods.
- `maxUnavailable: 1` — at most 1 Pod unavailable.
- `maxUnavailable: 25%` — at most 25% of Pods.

**Verification:**
```bash
kubectl get pdb -n production
kubectl describe pdb myapp-pdb -n production
```

**Important:** PDB only works with planned disruptions (drain, eviction). Kill -9 is not blocked.

DevOps: What is Pod Disruption Budget?