运行应用-使用Deployment运行无状态应用程序

以下介绍如何使用kubernetes的deployment对象运行应用程序。

目标

- 创建nginx deployment。

- 使用kubectl列出有关部署的信息。

- 更新部署

创建和探索nginx部署

可以通过创建kubernetes部署对象来运行应用程序，还可以在yaml文件中描述部署。例如，这个yaml文件描述了运行nginx:1.7.9 docker映像的部署：

application/deployment.yaml

apiVersion: apps/v1 # for versions before 1.9. use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas:  # tells deployment to run  pods matching the template
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.
        ports:
        - containerPort: 

注意：

selector字段定义Deployment如何查找要管理的pod。
在本例中，只需选择Pod模板中定义的标签（app:nginx）。然而，只要Pod模板本身满足规则，就可能有更复杂的选择规则。

1. 基于YAML文件创建deployment

kubectl apply -f application/deployment.yaml

2. 显示有关部署的信息：

kubectl describe deployment nginx-deployment

输出类似于：

user@computer:~/website$ kubectl describe deployment nginx-deployment
Name:     nginx-deployment
Namespace:    default
CreationTimestamp:  Tue,  Aug  :: -
Labels:     app=nginx
Annotations:    deployment.kubernetes.io/revision=
Selector:   app=nginx
Replicas:    desired |  updated |  total |  available |  unavailable
StrategyType:   RollingUpdate
MinReadySeconds:
RollingUpdateStrategy:   max unavailable,  max surge
Pod Template:
  Labels:       app=nginx
  Containers:
   nginx:
    Image:              nginx:1.7.
    Port:               /TCP
    Environment:        <none>
    Mounts:             <none>
  Volumes:              <none>
Conditions:
  Type          Status  Reason
  ----          ------  ------
  Available     True    MinimumReplicasAvailable
  Progressing   True    NewReplicaSetAvailable
OldReplicaSets:   <none>
NewReplicaSet:    nginx-deployment- (/ replicas created)
No events.

3. 列出demployment创建的Pods：

kubectl get pods -l app=nginx

输出类似于：

NAME                                READY     STATUS    RESTARTS   AGE
nginx-deployment--7o5ns   /       Running             16h
nginx-deployment--r18az   /       Running             16h

4. 显示Pod信息：

kubectl describe pod <pod-name>

<pod-name>是具体Pod的名称

更新Deployment

你可以通过应用新的yaml文件来更新部署。以下YAML文件将nginx更新到nginx 1.8

application/deployment-update.yaml

apiVersion: apps/v1 # for versions before 1.9. use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas:
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.8 # Update the version of nginx from 1.7. to 1.8
        ports:
        - containerPort: 

1.  应用新的yaml文件：

 kubectl apply -f application/deployment-update.yaml

2. 查看使用新名称创建的Pods并删除Pods：

 kubectl get pods -l app=nginx

通过增加副本计数来扩展应用程序

你可以通过应用新的yaml文件来增加部署中的Pod数量。此YAML文件将replicas设置为4，指定部署应具有四个pod：

application/deployment-scale.yaml

apiVersion: apps/v1 # for versions before 1.9. use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas:  # Update the replicas from  to
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.8
        ports:
        - containerPort: 

1.  应用新的yaml文件：

kubectl apply -f application/deployment-scale.yaml

2. 验证部署是否有四个Pod：

kubectl get pods -l app=nginx

输出类似于：

NAME                               READY     STATUS    RESTARTS   AGE
nginx-deployment--4zdqq   /       Running             25s
nginx-deployment--6zgi1   /       Running             25s
nginx-deployment--fxcez   /       Running             2m
nginx-deployment--rwovn   /       Running             2m

删除Deployment

通过Deployment的名称删除Deployment

kubectl delete deployment nginx-deployment