1、使用命令kubectl run创建应用

语法:  kubectl run NAME --image=image [--env="key=value"] [--port=port] [--replicas=replicas] [--dry-run=bool][--overrides=inline-json] [--command] -- [COMMAND] [args...] [options]

 实用举例：

[root@k8s-master ~]# kubectl run nginx-deploy --image=nginx:1.14-alpine --port=80 --replicas=1    #创建一个nginx的应用，副本数为1deployment.apps/nginx-deploy created[root@k8s-master ~]# kubectl get deployment　　#获取应用信息，查看应用是否符合预期状态NAME           DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGEnginx-deploy   1         1         1            1           40s[root@k8s-master ~]# kubectl get pods　　#获取pod信息NAME                          READY     STATUS    RESTARTS   AGEnginx-deploy-5b595999-44zwq   1/1       Running   0          1m[root@k8s-master ~]# kubectl get pods -o wide    #查看pod运行在哪个节点上NAME                          READY     STATUS    RESTARTS   AGE       IP           NODEnginx-deploy-5b595999-44zwq   1/1       Running   0          1m        10.244.2.2   k8s-node02

从上面创建的应用可以得知，nginx-deploy应用的pod的ip为10.244.2.2，这是一个pod ip，仅仅可以在集群内部访问，如下：

[root@k8s-master ~]# curl 10.244.2.2 -IHTTP/1.1 200 OKServer: nginx/1.14.0Date: Thu, 28 Feb 2019 06:13:03 GMTContent-Type: text/htmlContent-Length: 612Last-Modified: Fri, 06 Jul 2018 16:53:43 GMTConnection: keep-aliveETag: "5b3f9e97-264"Accept-Ranges: bytes[root@k8s-node01 ~]# curl 10.244.2.2 -IHTTP/1.1 200 OKServer: nginx/1.14.0Date: Thu, 28 Feb 2019 06:12:04 GMTContent-Type: text/htmlContent-Length: 612Last-Modified: Fri, 06 Jul 2018 16:53:43 GMTConnection: keep-aliveETag: "5b3f9e97-264"Accept-Ranges: bytes[root@k8s-node02 ~]# curl 10.244.2.2 -I                HTTP/1.1 200 OKServer: nginx/1.14.0Date: Thu, 23 Aug 2018 09:22:18 GMTContent-Type: text/htmlContent-Length: 612Last-Modified: Fri, 06 Jul 2018 16:53:43 GMTConnection: keep-aliveETag: "5b3f9e97-264"Accept-Ranges: bytes

这里要注意的是pod的客户端有2类，1类是其他pod，1类是集群外部客户端，那么集群外部的客户端如何访问到pod呢？pod的地址是随时变化的，假设先删除创建的pod：

[root@k8s-master ~]# kubectl delete pods nginx-deploy-5b595999-44zwqpod "nginx-deploy-5b595999-44zwq" deleted

要明白pod是通过控制器进行管理的，当控制器发现pod的状态不满足预期的状态时，将会重新创建一个pod

[root@k8s-master ~]# kubectl get pods -o wide    #由于在node01节点上没有镜像，需要重新下载NAME                          READY     STATUS              RESTARTS   AGE       IP        NODEnginx-deploy-5b595999-872c7   0/1       ContainerCreating   0          24s       
     
          k8s-node01[root@k8s-master ~]# kubectl get pods -o wideNAME                          READY     STATUS    RESTARTS   AGE       IP           NODEnginx-deploy-5b595999-872c7   1/1       Running   0          56s       10.244.1.2   k8s-node01
     

此时可以看到新建的pod的ip地址已经更改了，并且本次创建的pod是在node01节点上，这样就需要提供一个固定端点，给集群外部客户端进行访问。这个固定端点就是service：

语法如下:  kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP] [--target-port=number-or-name][--name=name] [--external-ip=external-ip-of-service] [--type=type] [options][root@k8s-master ~]# kubectl expose deployment nginx-deploy --name=nginx --port=80 --target-port=80 --protocol=TCP　　#创建一个nginx的serviceservice/nginx exposed[root@k8s-master ~]# kubectl get svcNAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEkubernetes   ClusterIP   10.96.0.1        
     
              443/TCP   1dnginx        ClusterIP   10.106.162.254   
      
               80/TCP    19s[root@k8s-master ~]# curl 10.106.162.254 -I　　#通过ClusterIP进行访问nginx podHTTP/1.1 200 OKServer: nginx/1.14.0Date: Thu, 23 Aug 2018 09:38:09 GMTContent-Type: text/htmlContent-Length: 612Last-Modified: Fri, 06 Jul 2018 16:53:43 GMTConnection: keep-aliveETag: "5b3f9e97-264"Accept-Ranges: bytes
      
     

10.106.162.254这网段依然是集群内部的网段，只能被集群内部所能访问，外部是无法通过service的ip进行访问的。那么针对pod的客户端除了通过service ip访问还可以通过service的名称进行访问，但是前提是需要对service的名称能够进行解析。而解析时是依赖coredns服务的，而我们本地的dns指向并非coredns，如下：

[root@k8s-master ~]# curl nginxcurl: (6) Could not resolve host: nginx; Unknown error[root@k8s-master ~]# cat /etc/resolv.conf# Generated by NetworkManagernameserver 8.8.8.8nameserver 114.114.114.114

下面查看一下coredns的ip地址：

[root@k8s-master ~]# kubectl get pods -n kube-system -o wide NAME                                 READY     STATUS    RESTARTS   AGE       IP              NODEcoredns-78fcdf6894-nmcmz             1/1       Running   0          1d        10.244.0.3      k8s-mastercoredns-78fcdf6894-p5pfm             1/1       Running   0          1d        10.244.0.2      k8s-masteretcd-k8s-master                      1/1       Running   1          1d        192.168.56.11   k8s-masterkube-apiserver-k8s-master            1/1       Running   8          1d        192.168.56.11   k8s-masterkube-controller-manager-k8s-master   1/1       Running   4          1d        192.168.56.11   k8s-masterkube-flannel-ds-n5c86                1/1       Running   0          1d        192.168.56.11   k8s-masterkube-flannel-ds-nrcw2                1/1       Running   0          5h        192.168.56.13   k8s-node02kube-flannel-ds-pgpr7                1/1       Running   1          1d        192.168.56.12   k8s-node01kube-proxy-glzth                     1/1       Running   0          5h        192.168.56.13   k8s-node02kube-proxy-rxlt7                     1/1       Running   1          1d        192.168.56.11   k8s-masterkube-proxy-vxckf                     1/1       Running   0          1d        192.168.56.12   k8s-node01kube-scheduler-k8s-master            1/1       Running   2          1d        192.168.56.11   k8s-master

而一般，也不会直接通过coredns的这个pod ip地址进行访问，而是通过service进行访问，查看一下coredns的service：

[root@k8s-master ~]# kubectl get svc -n kube-systemNAME       TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)         AGEkube-dns   ClusterIP   10.96.0.10   
     
              53/UDP,53/TCP   1d
     

那么就可以通过这个service ip：10.96.0.10进行解析上面的nginx服务，如下：

[root@k8s-master ~]# yum install -y bind-utils[root@k8s-master ~]# dig -t A nginx.default.svc.cluster.local @10.96.0.10　　#这里需要使用完整的服务名称，否则会因为dns搜索域的问题而导致无法解析成功; <<>> DiG 9.9.4-RedHat-9.9.4-61.el7 <<>> -t A nginx.default.svc.cluster.local @10.96.0.10;; global options: +cmd;; Got answer:;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 78;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1;; OPT PSEUDOSECTION:; EDNS: version: 0, flags:; udp: 4096;; QUESTION SECTION:;nginx.default.svc.cluster.local. IN    A;; ANSWER SECTION:nginx.default.svc.cluster.local. 5 IN    A    10.106.162.254　　#这样就可以正常解析出nginx的service ip了;; Query time: 155 msec;; SERVER: 10.96.0.10#53(10.96.0.10);; WHEN: Thu Aug 23 05:40:22 EDT 2018;; MSG SIZE  rcvd: 107

那么再演示通过pod 客户端进行访问：

[root@k8s-master ~]# kubectl run client --image=busybox --replicas=1 -it --restart=Never　　#创建pod[root@k8s-master ~]# kubectl exec -it client /bin/sh    #首次创建如果没进入到容器，可以使用这命令进入/ # cat /etc/resolv.conf 　　#查看dns，这里就是自动指向corednsnameserver 10.96.0.10search default.svc.cluster.local svc.cluster.local cluster.localoptions ndots:5/ # wget -O - -q http://nginx:80　　#请求解析nginx
Welcome to nginx!
If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.
For online documentation and support please refer tonginx.org.
Commercial support is available atnginx.com.
Thank you for using nginx.

这就是service提供给pod的固定访问端点的使用，而pod的增删改查，并不会影响通过service进行访问，可以通过以下命令来查看service的详细信息：

[root@k8s-master ~]# kubectl describe svc nginxName:              nginxNamespace:         defaultLabels:            run=nginx-deployAnnotations:       
     
      Selector:          run=nginx-deployType:              ClusterIPIP:                10.106.162.254Port:              
      
         80/TCPTargetPort:        80/TCPEndpoints:         10.244.1.5:80　　#pod 的ip，会根据资源变化改变，但是实际访问的service 依旧有效Session Affinity:  NoneEvents:            
       
      
     

那么pod的增删改，service又是如何确定对pod的访问呢？这就需要通过标签选择器进行选定，无论pod的ip如何变化，但是标签不会变化，从而达到固定端点的访问效果，查看一下pod的标签：

[root@k8s-master ~]# kubectl get pods --show-labelsNAME                          READY     STATUS    RESTARTS   AGE       LABELSclient                        1/1       Running   0          21h       run=clientnginx-deploy-5b595999-872c7   1/1       Running   2          22h       pod-template-hash=16151555,run=nginx-deploy

run=nginx-deploy就是这个应用的标签，所以当pod的改变，并不会影响service的访问。

2、应用副本的动态伸缩

语法如下: kubectl scale [--resource-version=version] [--current-replicas=count] --replicas=COUNT (-f FILENAME | TYPE NAME) （1）创建应用myapp [root@k8s-master ~]# kubectl run myapp --image=ikubernetes/myapp:v1 --replicas=2deployment.apps/myapp created[root@k8s-master ~]# kubectl get deployment NAME           DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGEmyapp          2         2         2            1           15snginx-deploy   1         1         1            1           22h（2）查看pod详细信息[root@k8s-master ~]# kubectl get pods -o wideNAME                          READY     STATUS         RESTARTS   AGE       IP           NODEclient                        1/1       Running        0          21h       10.244.2.3   k8s-node02client2                       1/1       Running        0          48m       10.244.1.6   k8s-node01client3                       1/1       Running        0          27m       10.244.2.4   k8s-node02myapp-848b5b879b-bdp7t        1/1       Running        0          26s       10.244.1.7   k8s-node01myapp-848b5b879b-swt2c        0/1       ErrImagePull   0          26s       10.244.2.5   k8s-node02nginx-deploy-5b595999-872c7   1/1       Running        2          22h       10.244.1.5   k8s-node01 （3）配置service端点[root@k8s-master ~]# kubectl expose deployment myapp --name=myapp --port=80service/myapp exposed （4）查看服务信息[root@k8s-master ~]# kubectl get svcNAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGEkubernetes   ClusterIP   10.96.0.1        
     
              443/TCP   2dmyapp        ClusterIP   10.106.67.242    
      
               80/TCP    14snginx        ClusterIP   10.106.162.254   
       
                80/TCP    21h （5）Pod客户端访问/ #  wget -O - -q http://myapp:80Hello MyApp | Version: v1 | 
        Pod Name （6）副本增加到5[root@k8s-master ~]# kubectl scale --replicas=5 deployment myappdeployment.extensions/myapp scaled[root@k8s-master ~]# kubectl get podsNAME                          READY     STATUS             RESTARTS   AGEclient                        1/1       Running            0          21hclient2                       1/1       Running            0          51mclient3                       1/1       Running            0          30mmyapp-848b5b879b-6p6ml        1/1       Running            0          1mmyapp-848b5b879b-7xmnj        0/1       ImagePullBackOff   0          1mmyapp-848b5b879b-bdp7t        1/1       Running            0          3mmyapp-848b5b879b-swt2c        0/1       ImagePullBackOff   0          3mmyapp-848b5b879b-zlvl2        1/1       Running            0          1mnginx-deploy-5b595999-872c7   1/1       Running            2          22h （7）副本收缩到3[root@k8s-master ~]# kubectl scale --replicas=3 deployment myappdeployment.extensions/myapp scaled
       
      
     

3、应用的版本升级

语法如下: kubectl set image (-f FILENAME | TYPE NAME) CONTAINER_NAME_1=CONTAINER_IMAGE_1 ... CONTAINER_NAME_N=CONTAINER_IMAGE_N

（1）版本升级为v2 [root@k8s-master ~]# kubectl set image deployment myapp myapp=ikubernetes/myapp:v2deployment.extensions/myapp image updated （2）查看升级过程[root@k8s-master ~]# kubectl rollout status deployment myapp    #查看更新过程Waiting for deployment "myapp" rollout to finish: 1 out of 3 new replicas have been updated...Waiting for deployment "myapp" rollout to finish: 1 out of 3 new replicas have been updated...Waiting for deployment "myapp" rollout to finish: 1 out of 3 new replicas have been updated...Waiting for deployment "myapp" rollout to finish: 2 out of 3 new replicas have been updated...Waiting for deployment "myapp" rollout to finish: 2 out of 3 new replicas have been updated...Waiting for deployment "myapp" rollout to finish: 2 out of 3 new replicas have been updated...Waiting for deployment "myapp" rollout to finish: 1 old replicas are pending termination...Waiting for deployment "myapp" rollout to finish: 1 old replicas are pending termination...deployment "myapp" successfully rolled out（3）获取pod信息[root@k8s-master ~]# kubectl get podsNAME                          READY     STATUS    RESTARTS   AGEclient                        1/1       Running   0          21hclient2                       1/1       Running   0          53mclient3                       1/1       Running   0          33mmyapp-74c94dcb8c-2djgg        1/1       Running   0          1mmyapp-74c94dcb8c-92d9p        1/1       Running   0          28smyapp-74c94dcb8c-nq7zt        1/1       Running   0          25snginx-deploy-5b595999-872c7   1/1       Running   2          22h[root@k8s-master ~]# kubectl describe pods myapp-74c94dcb8c-2djgg （4）pod客户端测试访问，可以看到是v2版本/ #  wget -O - -q http://myapp:80Hello MyApp | Version: v2 | Pod Name

4、应用的版本回滚

语法如下:

　kubectl rollout undo (TYPE NAME | TYPE/NAME) [flags] [options]

[root@k8s-master ~]# kubectl rollout undo deployment myapp    #不指定版本直接回滚到上一个版本deployment.extensions/myapp/ #  wget -O - -q http://myapp:80Hello MyApp | Version: v1 | Pod Name

5、实现外部访问service

[root@k8s-master ~]# kubectl edit svc myappTYPE:CLUSTER-IP改为TYPE:NodePort[root@k8s-master ~]# kubectl get svcNAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGEkubernetes   ClusterIP   10.96.0.1        
     
              443/TCP        2dmyapp        NodePort    10.106.67.242    
      
               80:32432/TCP   18mnginx        ClusterIP   10.106.162.254   
       
                80/TCP         22h
       
      
     

这里再查看service信息，可以看到myapp进行了端口映射，将myapp的80端口映射到本地32432端口，则可以使用http://192.168.56.11:32432进行访问。如图：