Kubernetes Pod 控制器 Deployment

概念

Kubernetes在V1.2版本开始，引入了Deployment控制器。

Deployment并不直接管理Pod，而是通过管理ReplicaSet来间接管理Pod。

特点

• 支持ReplicaSet的所有功能
• 支持发布的停止、继续
• 支持滚动升级和回滚版本

查看帮助

kubectl explain deployment

完整配置

apiVersion: apps/v1 # 版本号
kind: Deployment # 类型       
metadata: # 元数据
  name: # deploy 名称 
  namespace: # 所属命名空间 
  labels: #标签
    controller: deploy
spec: # 详情描述
  replicas: 3 # 副本数量
  revisionHistoryLimit: 3 # 保留历史版本
  paused: false # 暂停部署，默认是 false
  progressDeadlineSeconds: 600 # 部署超时时间（s），默认是 600
  strategy: # 策略
    type: RollingUpdate # 滚动更新策略
    rollingUpdate: # 滚动更新
      maxSurge: 30% # 最大额外可以存在的副本数，可以为百分比，也可以为整数。默认为25%。
      maxUnavailable: 30% # 最大不可用状态的 Pod 的最大值，可以为百分比，也可以为整数。默认为25%。
  selector: # 选择器，通过它指定该控制器管理哪些 Pod
    matchLabels:      # Labels 匹配规则
      app: nginx-pod
    matchExpressions: # Expressions匹配规则
      - {key: app, operator: In, values: [nginx-pod]}
  template: # 模板，当副本数量不足时，会根据下面的模板创建 Pod
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1
        ports:
        - containerPort: 80

示例 yml

pc-deployment.yml

apiVersion: apps/v1
kind: Deployment      
metadata:
  name: pc-deployment
  namespace: dev
spec: 
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1

创建 Deployment

kubectl create -f pc-deployment.yml

查看状态

kubectl get deploy -n dev

输出：

[root@localhost ~]# kubectl get deploy -n dev
NAME            READY   UP-TO-DATE   AVAILABLE   AGE
pc-deployment   3/3     3            3           16s

查看副本信息

kubectl get rs -n dev

输出：

[root@localhost ~]# kubectl get rs -n dev
NAME                       DESIRED   CURRENT   READY   AGE
pc-deployment-6f7f65b46d   3         3         3       107s

扩缩容

与ReplicaSet一样。

edit 方式

kubectl edit deploy pc-deployment -n dev

scale 方式

kubectl scale deploy pc-deployment --replicas=5  -n dev

镜像更新

Deployment支持两种更新策略：重建更新和滚动更新，可以通过strategy指定策略类型。

重建更新

Recreate

apiVersion: apps/v1
kind: Deployment      
metadata:
  name: pc-deployment
  namespace: dev
spec:
  strategy: # 策略
    type: Recreate # 重建更新
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1

滚动更新

RollingUpdate

apiVersion: apps/v1
kind: Deployment      
metadata:
  name: pc-deployment
  namespace: dev
spec:
  strategy: # 策略
    type: RollingUpdate # 滚动更新策略
    rollingUpdate:
      maxSurge: 25% 
      maxUnavailable: 25%
  replicas: 3
  selector:
    matchLabels:
      app: nginx-pod
  template:
    metadata:
      labels:
        app: nginx-pod
    spec:
      containers:
      - name: nginx
        image: nginx:1.17.1

版本回退

kubectl rollout：版本升级相关功能，支持下面的选项：

• status：显示当前升级状态
• history：显示升级历史记录
• pause：暂停版本升级过程
• resume：继续已经暂停的版本升级过程
• restart：重启版本升级过程
• undo：回滚到上一级版本（可以使用--to-revision回滚到指定版本）

查看当前升级版本的状态

kubectl rollout status deploy pc-deployment -n dev

输出：

[root@localhost ~]# kubectl rollout status deploy pc-deployment -n dev
deployment "pc-deployment" successfully rolled out

查看升级历史记录

kubectl rollout history deploy pc-deployment -n dev

输出：

[root@localhost ~]# kubectl rollout history deploy pc-deployment -n dev
deployment.apps/pc-deployment 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>
3         <none>

版本回滚

kubectl rollout undo deployment pc-deployment --to-revision=1 -n dev

输出：发现回到了1.17.1版本

[root@localhost ~]# kubectl rollout undo deployment pc-deployment --to-revision=1 -n dev
deployment.apps/pc-deployment rolled back
[root@localhost ~]# kubectl get deploy -n dev -o wide
NAME            READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS   IMAGES         SELECTOR
pc-deployment   2/2     2            2           22m   nginx        nginx:1.17.1   app=nginx-pod

查看 rs

Deployment之所以可是实现版本的回滚，就是通过记录下历史rs来实现的，一旦想回滚到哪个版本，只需要将当前版本Pod数量降为0，然后将回滚版本的Pod提升为目标数量就可以了。

[root@localhost ~]# kubectl get rs -n dev
NAME                       DESIRED   CURRENT   READY   AGE
pc-deployment-86f4996797   0         0         0       9m7s
pc-deployment-6f7f65b46d   2         2         2       23m
pc-deployment-79f7d88458   0         0         0       8m4s

金丝雀发布

Deployment控制器支持控制更新过程中的控制，如暂停(pause)或继续(resume)更新操作。

更新并暂停

kubectl set image deploy pc-deployment nginx=nginx:1.17.4 -n dev && kubectl rollout pause deployment pc-deployment -n dev

输出：

[root@localhost ~]# kubectl set image deploy pc-deployment nginx=nginx:1.17.4 -n dev && kubectl rollout pause deployment pc-deployment -n dev
deployment.apps/pc-deployment image updated
deployment.apps/pc-deployment paused

观察更新状态

kubectl rollout status deploy pc-deployment -n dev

输出：

[root@localhost ~]# kubectl rollout status deploy pc-deployment -n dev
Waiting for deployment "pc-deployment" rollout to finish: 1 out of 2 new replicas have been updated...
^C

监控更新的过程

kubectl get rs -n dev -o wide

输出：

[root@localhost ~]# kubectl get rs -n dev -o wide
NAME                       DESIRED   CURRENT   READY   AGE    CONTAINERS   IMAGES         SELECTOR
pc-deployment-86f4996797   0         0         0       17m    nginx        nginx:1.17.2   app=nginx-pod,pod-template-hash=86f4996797
pc-deployment-6f7f65b46d   2         2         2       32m    nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=6f7f65b46d
pc-deployment-79f7d88458   0         0         0       16m    nginx        nginx:1.17.3   app=nginx-pod,pod-template-hash=79f7d88458
pc-deployment-cf7c57879    1         1         1       119s   nginx        nginx:1.17.4   app=nginx-pod,pod-template-hash=cf7c57879

[root@localhost ~]# kubectl get pods -n dev
NAME                             READY   STATUS    RESTARTS   AGE
pc-deployment-6f7f65b46d-xxpzb   1/1     Running   0          12m
pc-deployment-6f7f65b46d-bqmhl   1/1     Running   0          12m
pc-deployment-cf7c57879-q8zqr    1/1     Running   0          3m19s

继续更新

kubectl rollout resume deploy pc-deployment -n dev

输出：

[root@localhost ~]# kubectl rollout resume deploy pc-deployment -n dev
deployment.apps/pc-deployment resumed

[root@localhost ~]# kubectl get rs -n dev -o wide
NAME                       DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES         SELECTOR
pc-deployment-86f4996797   0         0         0       20m     nginx        nginx:1.17.2   app=nginx-pod,pod-template-hash=86f4996797
pc-deployment-79f7d88458   0         0         0       19m     nginx        nginx:1.17.3   app=nginx-pod,pod-template-hash=79f7d88458
pc-deployment-cf7c57879    2         2         2       4m52s   nginx        nginx:1.17.4   app=nginx-pod,pod-template-hash=cf7c57879
pc-deployment-6f7f65b46d   0         0         0       35m     nginx        nginx:1.17.1   app=nginx-pod,pod-template-hash=6f7f65b46d
[root@localhost ~]# kubectl get pods -n dev
NAME                            READY   STATUS    RESTARTS   AGE
pc-deployment-cf7c57879-q8zqr   1/1     Running   0          5m1s
pc-deployment-cf7c57879-g9bxr   1/1     Running   0          51s

删除 Deployment

kubectl delete -f pc-deployment.yml