Roy学Kubernetes(10)：控制器之Deployments

Deployments又称部署控制器，它为Pod和ReplicaSet提供声明性更新，是ReplicaSet的高级使用方式。Deployment控制器会以可控的速率将ReplicaSet的实际状态更新到你所定义的状态。

使用案例

1. 部署ReplicaSet副本集
1. 更新Pod的状态
1. 部署回滚
1. Pod伸缩（扩容和缩减）
1. 暂停部署
1. 清除旧的ReplicaSet副本集

创建Deployment

nginx.yaml

apiVersion: apps/v1
kind: Deployment    # 指定Deployment类型
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3   # 指定副本数
  selector:
    matchLabels:    # 定义匹配Pod的标签，若有多个标签必须全匹配
      app: nginx
  template:   # Pod部署的模板
    metadata:
      labels:
        app: nginx  # Pod的标签
    spec:
      containers:   # 容器配置
      - name: nginx   # 容器名
        image: nginx:1.7.9    # 镜像
        ports:    # 映射端口及类型
        - containerPort: 80

创建

1	[root@node1 ~]# kubectl apply -f nginx.yaml

查询

1
2
3

[root@node1 ~]# kubectl get deployments   #deployments可简写为deploy
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   3         0         0            0           1s

NAME：部署名称。
DESIRED：显示应用程序所需的副本数。
CURRENT：显示当前正在运行的副本数。
UP-TO-DATE：显示已更新以实现所需状态的副本数。
AVAILABLE：显示用户可以使用的应用程序副本数量。
AGE：显示应用程序已运行的时间。

由上可知，当DESIRED、CURRENT、UP-TO-DATE、AVAILABLE这四个参数均相同时，Deployment部署状态才完全正常。

更新Deployment

更新nginx镜像

1 2	[root@node1 ~]# kubectl --record deployment.apps/nginx-deployment set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 deployment.apps/nginx-deployment image updated

–record：保存更改

或者，你可以直接编辑Deployment生效(类似vim操作方式)

1 2	[root@node1 ~]# kubectl edit deployment nginx-deployment deployment.apps/nginx-deployment edited

查看更新状态

1 2	[root@node1 ~]# kubectl rollout status deployment nginx-deployment Waiting for rollout to finish: 2 out of 3 new replicas have been updated...

查看ReplicaSet状态

[root@node1 ~]# kubectl get rs
NAME                          DESIRED   CURRENT   READY   AGE
nginx-deployment-1564180365   3         3         3       6s
nginx-deployment-2035384211   0         0         0       36s

查看Pod状态

[root@node1 ~]# kubectl get pods
NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment-1564180365-khku8   1/1       Running   0          14s
nginx-deployment-1564180365-nacti   1/1       Running   0          14s
nginx-deployment-1564180365-z9gth   1/1       Running   0          14s

查看pod标签

[root@node1 ~]# kubectl get pods --show-labels
NAME                                READY     STATUS    RESTARTS   AGE       LABELS
nginx-deployment-75675f5897-7ci7o   1/1       Running   0          18s       app=nginx,pod-template-hash=3123191453
nginx-deployment-75675f5897-kzszj   1/1       Running   0          18s       app=nginx,pod-template-hash=3123191453
nginx-deployment-75675f5897-qqcnn   1/1       Running   0          18s       app=nginx,pod-template-hash=3123191453

当更新Deployment时，Deployment默认总是会保持最少25%的Pod数量可用。

获取Deployment详细信息

[root@node1 ~]# kubectl describe deployments
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Thu, 30 Nov 2017 10:56:25 +0000
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision=2
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 3 available | 0 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
Labels:  app=nginx
 Containers:
  nginx:
    Image:        nginx:1.9.1
    Port:         80/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      True    MinimumReplicasAvailable
  Progressing    True    NewReplicaSetAvailable
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-1564180365 (3/3 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  2m    deployment-controller  Scaled up replica set nginx-deployment-2035384211 to 3
  Normal  ScalingReplicaSet  24s   deployment-controller  Scaled up replica set nginx-deployment-1564180365 to 1
  Normal  ScalingReplicaSet  22s   deployment-controller  Scaled down replica set nginx-deployment-2035384211 to 2
  Normal  ScalingReplicaSet  22s   deployment-controller  Scaled up replica set nginx-deployment-1564180365 to 2
  Normal  ScalingReplicaSet  19s   deployment-controller  Scaled down replica set nginx-deployment-2035384211 to 1
  Normal  ScalingReplicaSet  19s   deployment-controller  Scaled up replica set nginx-deployment-1564180365 to 3
  Normal  ScalingReplicaSet  14s   deployment-controller  Scaled down replica set nginx-deployment-2035384211 to 0

通常的，Events显示的内容对我们在排查问题时很有用处。

注：不推荐更新Deployment中的标签selector，建议事先规划好selector；如果必须要更新，需要按按指定流程谨慎操作。

回滚Deployment

某些情况下你可能想要回滚部署; 例如，当部署不稳定或崩溃时。默认情况下，所有Deployment的部署历史记录（即修订历史）都保留在系统中，以便随时回滚（可以通过修改修订历史记录限制来更改，默认保留10条）。

注意：触发Deployment的部署时会创建Deployment的修订版。这意味着当且仅当部署的Pod模板（.spec.template）发生更改时才会创建新修订，例如更新模板的标签或容器图像。其他更新（例如扩展部署）不会创建部署版本，因此可以方便地同时进行手动或自动扩展。这意味着当你回滚到早期版本时，仅回滚Deployment的Pod模板部分，不会变更你的副本数。

首先需要获取历史版本

[root@node1 ~]# kubectl rollout history deployment nginx-deployment
deployments "nginx-deployment"
REVISION    CHANGE-CAUSE
1           kubectl apply --filename=https://k8s.io/examples/controllers/nginx-deployment.yaml --record=true
2           kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true
3           kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.91 --record=true

查看指定版本

[root@node1 ~]# kubectl rollout history deployment nginx-deployment --revision=2
deployments "nginx-deployment" revision 2
  Labels:       app=nginx
          pod-template-hash=1159050644
  Annotations:  kubernetes.io/change-cause=kubectl set image deployment.v1.apps/nginx-deployment nginx=nginx:1.9.1 --record=true
  Containers:
   nginx:
    Image:      nginx:1.9.1
    Port:       80/TCP
     QoS Tier:
        cpu:      BestEffort
        memory:   BestEffort
    Environment Variables:      <none>
  No volumes.

CHANGE-CAUSE是你的历史版本的备注信息，你可以使用如下命令来修改它

1	[root@node1 ~]# kubectl annotate deployment nginx-deployment change-cause="image updated to 1.9.1"

回滚

回滚到上一版本

1 2	[root@node1 ~]# kubectl rollout undo deployment nginx-deployment deployment.apps/nginx-deployment

回滚到指定版本

1 2	[root@node1 ~]# kubectl rollout undo deployment nginx-deployment --to-revision=2 deployment.apps/nginx-deployment

伸缩Deployment

手动伸缩

1 2	[root@node1 ~]# kubectl scale deployment nginx-deployment --replicas=10 deployment.apps/nginx-deployment scaled

自动伸缩

最小10个，最大15个副本，根据CPU使用率（80%上限）来自动判断。关于自动伸缩，参见。

1 2	[root@node1 ~]# kubectl autoscale deployment ginx-deployment --min=10 --max=15 --cpu-percent=80 deployment.apps/nginx-deployment scaled

暂停和继续Deployment

当你部署实施还未完成时，如果想要中途更新配置，你可以使用Deployment暂停和继续的操作。

暂停部署（假设nginx-deployment部署正在进行中，还未完成）

1 2	[root@node1 ~]# kubectl rollout pause deployment nginx-deployment deployment.apps/nginx-deployment paused

添加你的一个或多个更新操作

[root@node1 ~]# kubectl set image deployment nginx-deployment nginx=nginx:1.9.1
deployment.apps/nginx-deployment image updated
[root@node1 ~]# kubectl set resources deployment nginx-deployment -c=nginx --limits=cpu=200m,memory=512Mi
deployment.apps/nginx-deployment resource requirements updated

此时，还未生成新的修订版。

继续Deployment

1 2	[root@node1 ~]# kubectl rollout resume deployment nginx-deployment deployment.apps/nginx-deployment resumed