---
title: "Deployment"
---

Deployment为Pod和ReplicaSet提供了一个声明式定义(declarative)方法，用来替代以前的ReplicationController来方便的管理应用。典型的应用场景包括：

- 定义Deployment来创建Pod和ReplicaSet
- 滚动升级和回滚应用
- 扩容和缩容
- 暂停和继续Deployment

比如一个简单的nginx应用可以定义为

```yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 3
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80
```

扩容：

```
kubectl scale deployment nginx-deployment --replicas 10
```

如果集群支持 horizontal pod autoscaling 的话，还可以为Deployment设置自动扩展：

```
kubectl autoscale deployment nginx-deployment --min=10 --max=15 --cpu-percent=80
```

更新镜像也比较简单:

```
kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1
```

回滚：

```
kubectl rollout undo deployment/nginx-deployment
```