What is Kubernetes Pod OS field?

Question

Accepted Answer

**Pod OS** — specify the operating system for Pod scheduling and runtime.

```yaml
apiVersion: v1
kind: Pod
metadata:
  name: linux-pod
spec:
  os:
    name: linux
  containers:
  - name: app
    image: nginx:latest
---
apiVersion: v1
kind: Pod
metadata:
  name: windows-pod
spec:
  os:
    name: windows
  nodeSelector:
    kubernetes.io/os: windows
  containers:
  - name: app
    image: mcr.microsoft.com/dotnet/runtime:8.0
---
# Mixed OS cluster
apiVersion: apps/v1
kind: Deployment
metadata:
  name: cross-platform-app
spec:
  replicas: 6
  template:
    metadata:
      labels:
        app: cross-platform
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: kubernetes.io/os
                operator: In
                values:
                - linux
                - windows
      containers:
      - name: app
        image: myapp:latest
```

```bash
# Check node OS
kubectl get nodes -o custom-columns=NAME:.metadata.name,OS:.status.nodeInfo.operatingSystem
kubectl get nodes -l kubernetes.io/os=linux
kubectl get nodes -l kubernetes.io/os=windows
```

**Behavior:**
- Pods are scheduled to matching OS nodes.
- Mixed clusters: Linux + Windows nodes.
- OS-specific images required.

DevOps: What is Kubernetes Pod OS field?