kubernetes资源清单之Deployment

Deployment为Pod和ReplicaSets提供声明性更新

示例

---
apiVersion: apps/v1
kind: Deployment
metadata:
     name: deploy-myweb
     namespace: default
spec:
     replicas: 3
     selector:
         matchLabels:
             app: myweb
             tier: frontend
     template:
         metadata:
             namespace: default
             labels:
                 app: myweb
                 tier: frontend
         spec:
             containers:
               - name: container-myweb
                 image: mycloudedu/myweb:v1
                 imagePullPolicy: IfNotPresent

将清单提交给kubernetes集群，将创建定义的Deployment及其管理的ReplicaSet与pod

[root@master kubernetes]# kubectl apply -f deploy-myweb.yaml

验证

[root@master kubernetes]# kubectl get deployment
NAME           READY   UP-TO-DATE   AVAILABLE   AGE
deploy-myweb   3/3     3            3           89s

[root@master kubernetes]# kubectl get rs
NAME                      DESIRED   CURRENT   READY   AGE
deploy-myweb-85996f4d65   3         3         3       111s

[root@master kubernetes]# kubectl get pod
NAME                            READY   STATUS    RESTARTS   AGE
deploy-myweb-85996f4d65-4dr58   1/1     Running   0          6s
deploy-myweb-85996f4d65-8vfhl   1/1     Running   0          6s
deploy-myweb-85996f4d65-qsfmj   1/1     Running   0          6s

这里只阐述几个字段：.spec.replicas、.spec.selector、.spec.strategy、.spec.revisionHistoryLimit、.spec.template五个字段。其他字段跟前两篇文章差不多，这里不作阐述。想了解请点击这里。

kubectl explain deployment.spec

replicas    <integer>                          #是指期望值的pod数

selector <Object> -required-              #标签选择器，kubernetes根据这个标签查看有几个pod。符不符ReplicaSet合期望值

strategy <Object>                             #更新pod的策略

template <Object> -required-             #创建pod的模板

revisionHistoryLimit    <integer>         #保存几个历史版本，默认是10个

kubectl explain deployment.spec.selector有两种用法：

matchExpressions  <[]Object>

matchLabels    <map[string]string>

示例一：键与值的关系

matchExpressions:

- key:KEY

operator： (In, NotIn, Exists and DoesNotExist)

values: [VALUES1,VALUES2,…]

示例二：

matchLabels:

KEY:VALUES

kubectl explain deployment.spec.strategy

rollingUpdate <Object>       #当type是RollingUpdate，这个字段才生效

type    <string>                  #类型有两种Recreate与RollingUpdate，默认是RollingUpdate

当type=Recreate时，重新创建pod。当type=RollingUpdata时，重新创建pod是由策略规划。

这里讲解一下type=RollingUpdata。

kubectl explain deployment.spec.strategy.rollingUpdate有两个字段：

maxSurge    <string>              #最多能多几个pod

maxUnavailable    <string>      #最多能少几个pod

示例：

rollingUpdate:

maxSurge: <integer>

maxUnavailable: <integer>

这里template不阐述，说几个注意事项：

1.metadata.name这项可以不定义。因为定义了也不会生效。

2.metadata.labels必须含有selector的标签。

3.spec与pod的spec是一样的，这里就不在说明了。需要了解的查看上面文章。

综合示例

---
apiVersion: apps/v1
kind: Deployment
metadata:
     name: deploy-myweb
     namespace: default
spec:
     replicas: 3
     selector:
         matchLabels:
             app: myweb
             tier: frontend
     strategy:
         type: RollingUpdate
         rollingUpdate:
             maxSurge: 1
             maxUnavailable: 1
     revisionHistoryLimit: 3
     template:
         metadata:
             namespace: default
             labels:
                 app: myweb
                 tier: frontend
         spec:
             containers:
               - name: container-myweb
                 image: mycloudedu/myweb:v1
                 imagePullPolicy: IfNotPresent

验证

[root@master kubernetes]# kubectl describe deploy deploy-myweb

…

RollingUpdateStrategy:  1 max unavailable, 1 max surge

用打补丁的方式修改策略

[root@master kubernetes]# kubectl patch deployments deploy-myweb -p '{"spec":{"strategy":{"rollingUpdate":{"maxSurge":2,"maxUnavailable":0}}}}'
deployment.apps/deploy-myweb patched

验证

[root@master kubernetes]# kubectl describe deploy deploy-myweb

…

RollingUpdateStrategy:  0 max unavailable, 2 max surge

更新版本，定义更新一个版本暂停。是否跟定义更新策略进行更新

[root@master kubernetes]# kubectl set image deployments deploy-myweb container-myweb=mycloudedu/myweb:v2 && kubectl rollout pause deployment/deploy-myweb
deployment.apps/deploy-myweb image updated
deployment.apps/deploy-myweb paused

[root@master ~]# kubectl get pod -w
NAME                            READY   STATUS    RESTARTS   AGE
deploy-myweb-85996f4d65-4dr58   1/1     Running   0          57m
deploy-myweb-85996f4d65-8vfhl   1/1     Running   0          57m
deploy-myweb-85996f4d65-qsfmj   1/1     Running   0          57m
deploy-myweb-7fff44cfb8-cvbxf   0/1     Pending   0          0s
deploy-myweb-7fff44cfb8-h47lb   0/1     Pending   0          0s
deploy-myweb-7fff44cfb8-cvbxf   0/1     Pending   0          0s
deploy-myweb-7fff44cfb8-h47lb   0/1     Pending   0          0s
deploy-myweb-7fff44cfb8-cvbxf   0/1     ContainerCreating   0          0s
deploy-myweb-7fff44cfb8-h47lb   0/1     ContainerCreating   0          0s
deploy-myweb-7fff44cfb8-h47lb   1/1     Running             0          3s
deploy-myweb-7fff44cfb8-cvbxf   1/1     Running             0          3s

原本三个pod还是运行，后面创建一个pod。上面定义的策略是：允许最多多两个，不能减少pod。结论：符合更新策略

取消暂时更新

[root@master kubernetes]# kubectl rollout resume deploy/deploy-myweb
deployment.apps/deploy-myweb resumed

验证

[root@master ~]# kubectl rollout status deploy deploy-myweb
Waiting for deployment "deploy-myweb" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment spec update to be observed...
Waiting for deployment spec update to be observed...
Waiting for deployment "deploy-myweb" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "deploy-myweb" rollout to finish: 2 out of 3 new replicas have been updated...
Waiting for deployment "deploy-myweb" rollout to finish: 1 old replicas are pending termination...
Waiting for deployment "deploy-myweb" rollout to finish: 1 old replicas are pending termination...
deployment "deploy-myweb" successfully rolled out

[root@master kubernetes]# kubectl get deploy -o wide
NAME           READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS        IMAGES                SELECTOR
deploy-myweb   3/3     3            3           65m   container-myweb   mycloudedu/myweb:v2   app=myweb,tier=frontend

查看历史版本

[root@master kubernetes]# kubectl rollout history deployments deploy-myweb
deployment.apps/deploy-myweb
REVISION  CHANGE-CAUSE
1         <none>
2         <none>

回滚历史版本

[root@master kubernetes]# kubectl rollout undo deploy/deploy-myweb --to-revision=1
deployment.apps/deploy-myweb rolled back

验证

[root@master kubernetes]# kubectl get deploy -o wide
NAME           READY   UP-TO-DATE   AVAILABLE   AGE   CONTAINERS        IMAGES                SELECTOR
deploy-myweb   3/3     3            3           67m   container-myweb  mycloudedu/myweb:v1   app=myweb,tier=frontend