Deployment YAML方式创建Nginx服务

replication controller

Replication Controller为Kubernetes的一个核心内容，应用托管到Kubernetes之后，需要保证应用能够持续的运行，Replication Controller就是这个保证的key，主要的功能如下：

1.确保pod数量：它会确保Kubernetes中有指定数量的Pod在运行。如果少于指定数量的pod，Replication Controller会创建新的，反之则会删除掉多余的以保证Pod数量不变。
2.确保pod健康：当pod不健康，运行出错或者无法提供服务时，Replication Controller也会杀死不健康的pod，重新创建新的。
3.弹性伸缩 ：在业务高峰或者低峰期的时候，可以通过Replication Controller动态的调整pod的数量来提高资源的利用率。同时，配置相应的监控功能（Hroizontal Pod Autoscaler），会定时自动从监控平台获取Replication Controller关联pod的整体资源使用情况，做到自动伸缩。
4.滚动升级：滚动升级为一种平滑的升级方式，通过逐步替换的策略，保证整体系统的稳定，在初始化升级的时候就可以及时发现和解决问题，避免问题不断扩大。

Deployment

Deployment同样为Kubernetes的一个核心内容，主要职责同样是为了保证pod的数量和健康，90%的功能与Replication Controller完全一样，可以看做新一代的Replication Controller。但是，它又具备了Replication Controller之外的新特性： 

1.Replication Controller全部功能：Deployment继承了上面描述的Replication Controller全部功能。 
2.事件和状态查看：可以查看Deployment的升级详细进度和状态。 
3.回滚：当升级pod镜像或者相关参数的时候发现问题，可以使用回滚操作回滚到上一个稳定的版本或者指定的版本。 
4.版本记录: 每一次对Deployment的操作，都能保存下来，给予后续可能的回滚使用。 
5.暂停和启动：对于每一次升级，都能够随时暂停和启动。 
6.多种升级方案：Recreate：删除所有已存在的pod,重新创建新的; RollingUpdate：滚动升级，逐步替换的策略，同时滚动升级时，支持更多的附加参数，例如设置最大不可用pod数量，最小升级间隔时间等等。

1、创建deployment
[root@linux-node1 ~]# vim nginx-deployment.yaml　　#使用yaml的方式进行创建应用
apiVersion: apps/v1　　#apiVersion是当前配置格式的版本
kind: Deployment　　　　#kind是要创建的资源类型，这里是Deploymnet
metadata:　　　　　　　　#metadata是该资源的元数据，name是必须的元数据项
  name: nginx-deployment
  labels:
    app: nginx
spec:　　　　　　　　　　#spec部分是该Deployment的规则说明
  replicas: 3　　　　　 #relicas指定副本数量，默认为1
  selector:
    matchLabels:
      app: nginx
  template:　　　　　　#template定义Pod的模板，这是配置的重要部分
    metadata:　　　　  #metadata定义Pod的元数据，至少要顶一个label，label的key和value可以任意指定
      labels:
        app: nginx
    spec:　　　　　　　#spec描述的是Pod的规则，此部分定义pod中每一个容器的属性，name和image是必需的
      containers:
      - name: nginx
        image: nginx:1.13.12
        ports:
        - containerPort: 80

[root@linux-node1 ~]# kubectl create -f nginx-deployment.yaml #创建nginx-deployment应用
deployment.apps "nginx-deployment" created

2、查看deployment

[root@linux-node1 ~]# kubectl get deployment
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
net-test           2         2         2            2           32m
nginx-deployment   3         3         3            0           10s
   
[root@linux-node1 ~]# kubectl describe deployment nginx-deployment    #查看deployment详情
Name:                   nginx-deployment
Namespace:              default
CreationTimestamp:      Thu, 16 Aug 2018 16:13:37 +0800
Labels:                 app=nginx
Annotations:            deployment.kubernetes.io/revision=1
Selector:               app=nginx
Replicas:               3 desired | 3 updated | 3 total | 0 available | 3 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        nginx:1.13.12
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      False   MinimumReplicasUnavailable
  Progressing    True    ReplicaSetUpdated
OldReplicaSets:  <none>
NewReplicaSet:   nginx-deployment-6c45fc49cb (3/3 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  1m    deployment-controller  Scaled up replica set nginx-deployment-6c45fc49cb to 3

3、查看Pod

[root@linux-node1 ~]# kubectl get pod    #查看pod在状态，正在创建中，此时应该正在拉取镜像
NAME                                READY     STATUS              RESTARTS   AGE
net-test-5767cb94df-djt98           1/1       Running             0          22m
net-test-5767cb94df-hcwv7           1/1       Unknown             0          34m
net-test-5767cb94df-zb8m4           1/1       Running             0          34m
nginx-deployment-6c45fc49cb-dmc22   0/1       ContainerCreating   0          2m
nginx-deployment-6c45fc49cb-fd8xm   0/1       ContainerCreating   0          2m
nginx-deployment-6c45fc49cb-sc8sh   0/1       ContainerCreating   0          2m
   
[root@linux-node1 ~]# kubectl describe pod nginx-deployment-6c45fc49cb-dmc22  #查看具体某个pod的状态信息
   
[root@linux-node1 ~]# kubectl get pod -o wide　　#创建成功，状态为Running
NAME                                READY     STATUS    RESTARTS   AGE       IP          NODE
net-test-5767cb94df-djt98           1/1       Running   0          24m       10.2.73.3   192.168.56.13
net-test-5767cb94df-hcwv7           1/1       Unknown   0          36m       10.2.10.2   192.168.56.12
net-test-5767cb94df-zb8m4           1/1       Running   0          36m       10.2.73.2   192.168.56.13
nginx-deployment-6c45fc49cb-dmc22   1/1       Running   0          4m        10.2.73.6   192.168.56.13
nginx-deployment-6c45fc49cb-fd8xm   1/1       Running   0          4m        10.2.73.4   192.168.56.13
nginx-deployment-6c45fc49cb-sc8sh   1/1       Running   0          4m        10.2.73.5   192.168.56.13

Deployment、ReplicaSet、Pod 都已经就绪。如果要删除这些资源，执行 kubectl delete deployment nginx-deployment 或者 kubectl delete -f nginx-deployment.yaml。

4、测试Pod访问
[root@linux-node1 ~]# curl --head http://10.2.73.6
HTTP/1.1 200 OK
Server: nginx/1.13.12
Date: Thu, 16 Aug 2018 08:18:14 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes

5、更新Deployment

[root@linux-node1 ~]# kubectl set image deployment/nginx-deployment nginx=nginx:1.15.2 --record    #nginx的版本升级，由1.13.2升级为1.15.2，记录需要加参数--record
deployment.apps "nginx-deployment" image updated
   
[root@linux-node1 ~]# kubectl get deployment -o wide　　#查看更新后的deployment，可以看到当前4个副本，说明还在滚动升级中
NAME               DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE       CONTAINERS   IMAGES         SELECTOR
net-test           2         2         2            2           39m       net-test     alpine         run=net-test
nginx-deployment   3         4         1            3           6m        nginx        nginx:1.15.2   app=nginx

6、查看更新历史
[root@linux-node1 ~]# kubectl rollout history deployment/nginx-deployment #查看更新历史记录
deployments "nginx-deployment"
REVISION  CHANGE-CAUSE
1         <none>
2         kubectl set image deployment/nginx-deployment nginx=nginx:1.15.2 --record=true

7、查看具体某一个版本的升级历史

[root@linux-node1 ~]# kubectl rollout history deployment/nginx-deployment --revision=1
deployments "nginx-deployment" with revision #1
Pod Template:
  Labels:    app=nginx
    pod-template-hash=2701970576
  Containers:
   nginx:
    Image:    nginx:1.13.12
    Port:    80/TCP
    Host Port:    0/TCP
    Environment:    <none>
    Mounts:    <none>
  Volumes:    <none>

8、查看更新后的Deployment，并进行访问

[root@linux-node1 ~]# kubectl get pod -o wide
NAME                                READY     STATUS    RESTARTS   AGE       IP          NODE
net-test-5767cb94df-djt98           1/1       Running   0          30m       10.2.73.3   192.168.56.13
net-test-5767cb94df-hcwv7           1/1       Unknown   0          42m       10.2.10.2   192.168.56.12
net-test-5767cb94df-zb8m4           1/1       Running   0          42m       10.2.73.2   192.168.56.13
nginx-deployment-64749d4b59-djttr   1/1       Running   0          37s       10.2.73.8   192.168.56.13
nginx-deployment-64749d4b59-jp7fw   1/1       Running   0          3m        10.2.73.7   192.168.56.13
nginx-deployment-64749d4b59-q4fsn   1/1       Running   0          33s       10.2.73.9   192.168.56.13
[root@linux-node1 ~]# curl --head http://10.2.73.7
HTTP/1.1 200 OK
Server: nginx/1.15.2　　#版本已经升级为1.15.2
Date: Thu, 16 Aug 2018 08:24:09 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Tue, 24 Jul 2018 13:02:29 GMT
Connection: keep-alive
ETag: "5b572365-264"
Accept-Ranges: bytes

9、快速回滚到上一个版本

[root@linux-node1 ~]# kubectl rollout undo deployment/nginx-deployment   #回滚上一个版本
deployment.apps "nginx-deployment"    
   
[root@linux-node1 ~]# kubectl get pod -o wide
NAME                                READY     STATUS    RESTARTS   AGE       IP           NODE
net-test-5767cb94df-djt98           1/1       Running   0          32m       10.2.73.3    192.168.56.13
net-test-5767cb94df-hcwv7           1/1       Unknown   0          43m       10.2.10.2    192.168.56.12
net-test-5767cb94df-zb8m4           1/1       Running   0          43m       10.2.73.2    192.168.56.13
nginx-deployment-6c45fc49cb-b9h84   1/1       Running   0          24s       10.2.73.11   192.168.56.13
nginx-deployment-6c45fc49cb-g4mrg   1/1       Running   0          26s       10.2.73.10   192.168.56.13
nginx-deployment-6c45fc49cb-k29kq   1/1       Running   0          21s       10.2.73.12   192.168.56.13
[root@linux-node1 ~]# curl --head http://10.2.73.10
HTTP/1.1 200 OK
Server: nginx/1.13.12
Date: Thu, 16 Aug 2018 08:25:35 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes

回滚完成，每一次更新或者回滚ip都会变化，所以需要通过vip进行访问，这就引入了service   

10、使用service的vip进行访问应用

[root@linux-node1 ~]# vim nginx-service.yaml　　#使用yaml方式创建service
kind: Service
apiVersion: v1
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80

[root@linux-node1 ~]# kubectl create -f nginx-service.yaml 　　#创建service
service "nginx-service" created

[root@linux-node1 ~]# kubectl get service
NAME            TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
kubernetes      ClusterIP   10.1.0.1       <none>        443/TCP   4h
nginx-service   ClusterIP   10.1.213.126   <none>        80/TCP    15s　　#这个就是vip

[root@linux-node2 ~]# curl --head http://10.1.213.126　　#在node2节点上进行访问vip测试，在node1上无法访问是因为没有安装kube-proxy导致无法访问
HTTP/1.1 200 OK
Server: nginx/1.13.12
Date: Thu, 16 Aug 2018 08:30:08 GMT
Content-Type: text/html
Content-Length: 612
Last-Modified: Mon, 09 Apr 2018 16:01:09 GMT
Connection: keep-alive
ETag: "5acb8e45-264"
Accept-Ranges: bytes

11、扩容到5个节点

[root@linux-node1 ~]# kubectl scale deployment nginx-deployment --replicas 5　　#对应用的副本数进行扩容，直接指定副本数为5
deployment.extensions "nginx-deployment" scaled

[root@linux-node1 ~]# kubectl get pod　　#查看pod状态，可以看到已经增加到5个副本
NAME                                READY     STATUS    RESTARTS   AGE
net-test-5767cb94df-djt98           1/1       Running   0          38m
net-test-5767cb94df-hcwv7           1/1       Unknown   0          50m
net-test-5767cb94df-zb8m4           1/1       Running   0          50m
nginx-deployment-6c45fc49cb-b9h84   1/1       Running   0          6m
nginx-deployment-6c45fc49cb-g4mrg   1/1       Running   0          7m
nginx-deployment-6c45fc49cb-k29kq   1/1       Running   0          6m
nginx-deployment-6c45fc49cb-n9qkx   1/1       Running   0          24s
nginx-deployment-6c45fc49cb-xpx9s   1/1       Running   0          24s

##扩容与减容

　 #kubectl get deployment ##获取deployment名称
  #kubectl scale deployment nginx-deployment --replicas=3 扩容到3个
  #kubectl scale deployment nginx-deployment --replicas=1 恢复成1个

##动态处理CPU资源

#kubectl autoscale deployment nginx-deployment --min=2 --max=10 --cpu-percent=80