kubernetes快速应用入门

kubectl 就是 api server的客户端工具

创建一个nginx的pod

[root@master ~]# kubectl run nginx-deploy --image=nginx:1.14-alpine --port=80 --replicas=1
kubectl run --generator=deployment/apps.v1 is DEPRECATED and will be removed in a future version. Use kubectl run --generator=run-pod/v1 or kubectl create instead.
deployment.apps/nginx-deploy created

查看pod状态

[root@master ~]# kubectl get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deploy 1/1 1 1 54s

[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx-deploy-55d8d67cf-xdxcj 1/1 Running 0 85s

[root@master ~]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-deploy-55d8d67cf-xdxcj 1/1 Running 0 2m4s 10.244.1.2 node1

[root@node1 ~]# ifconfig
cni0: flags=4163 mtu 1450
　　inet 10.244.1.1 netmask 255.255.255.0 broadcast 0.0.0.0
　　inet6 fe80::ac25:6fff:fe19:4a09 prefixlen 64 scopeid 0x20
　　ether ae:25:6f:19:4a:09 txqueuelen 1000 (Ethernet)
　　RX packets 1 bytes 28 (28.0 B)
　　RX errors 0 dropped 0 overruns 0 frame 0
　　TX packets 8 bytes 656 (656.0 B)
　　TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

10.244.1.1这个网段是24位掩码，因此10.244.1都是网络地址，它是整个大网10.244.0.0/16位掩码的一个子网。这个子网专供node1上的pod使用。
node2上面的都是10.244.2.1开始。和node1不冲突。

[root@node2 ~]# curl 10.244.1.2

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

这时说明nginx的pod已经运行起来了。

这时的nginx只能被集群内部访问，还没法对外，所以需要创建service层来代理。

[root@master ~]# kubectl expose deployment nginx-deploy --name=nginx --port=80 --target-port=80 --protocol=TCP
service/nginx exposed

把deployment控制器相关的pod资源都创建为一个服务nginx-deploy，而服务名字叫nignx ，服务的端口号为80，pod的端口号，TCP服务。默认用的是Cluster-IP

[root@master ~]# kubectl get svc (svc是services的简写)
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 443/TCP 3d
nginx ClusterIP 10.96.69.143 80/TCP 3m24s

nginx的CLUSTER-IP是动态生成的，10.96.69.143是10.96.0.0/12位掩码中的地址。暴露的地址是80端口。

[root@master ~]# curl 10.96.69.143

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

这时候，访问service的地址就可以访问nginx了，依然在外部是访问不到的，因为创建service的时候用的是默认的CLUSTER-IP模式，是被集群内部pod客户端访问的。基于service自己的名称所访问的。

[root@master ~]# curl nginx
curl: (6) Could not resolve host: nginx; 未知的名称或服务

这时还是必须指定IP地址才能访问，因为还没有用DNS解析IP地址呢。所以需要去解析IP地址，这样以后直接访问ningx服务名就行了不用理IP地址。

查看DNS的地址：

[root@master ~]# kubectl get pods -n kube-system -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
coredns-fb8b8dccf-8lczd 1/1 Running 1 3d 10.244.0.5 master
coredns-fb8b8dccf-rljmp 1/1 Running 1 3d 10.244.0.4 master
etcd-master 1/1 Running 3 3d 192.168.163.100 master
kube-apiserver-master 1/1 Running 4 3d 192.168.163.100 master
kube-controller-manager-master 1/1 Running 9 3d 192.168.163.100 master
kube-flannel-ds-amd64-26kk7 1/1 Running 1 26h 192.168.163.102 node2
kube-flannel-ds-amd64-428x9 1/1 Running 1 26h 192.168.163.101 node1
kube-flannel-ds-amd64-mj4s6 1/1 Running 1 28h 192.168.163.100 master
kube-proxy-5s2gz 1/1 Running 1 26h 192.168.163.101 node1
kube-proxy-lwntd 1/1 Running 3 3d 192.168.163.100 master
kube-proxy-tjcpd 1/1 Running 1 26h 192.168.163.102 node2
kube-scheduler-master 1/1 Running 8 3d 192.168.163.100 master

[root@master ~]# kubectl get svc -n kube-system
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kube-dns ClusterIP 10.96.0.10 53/UDP,53/TCP,9153/TCP 3d

安装解析命令：

[root@master ~]# yum -y install bind-utils

创建一个临时的客户端进去设置DNS
[root@master ~]# kubectl run client1 --image=busybox --replicas=1 -it --restart=Never
If you don't see a command prompt, try pressing enter.
/ # cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5

default.svc.cluster.local 是一个特殊域名， 表示是你的kubenetes集群的本地pod资源特定后缀，而default表示这个pod所属的名称空间的名字，如果不给完整的名称，搜索的时候就搜索的域就不一样。

[root@master ~]# dig -t A nginx.default.svc.cluster.local @10.96.0.10

; <<>> DiG 9.9.4-RedHat-9.9.4-73.el7_6 <<>> -t A nginx.default.svc.cluster.local @10.96.0.10
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18720
;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
;; WARNING: recursion requested but not available

;; 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 10.96.69.143

;; Query time: 3 msec
;; SERVER: 10.96.0.10#53(10.96.0.10)
;; WHEN: 四 5月 16 10:05:59 CST 2019
;; MSG SIZE rcvd: 107

[root@master ~]# kubectl run client1 --image=busybox --replicas=1 -it --restart=Never
If you don't see a command prompt, try pressing enter.
/ # cat /etc/resolv.conf
nameserver 10.96.0.10
search default.svc.cluster.local svc.cluster.local cluster.local
options ndots:5
/ # nslookup nginx
Server: 10.96.0.10
Address: 10.96.0.10:53

Name: nginx.default.svc.cluster.local
Address: 10.96.69.143

*** Can't find nginx.svc.cluster.local: No answer
*** Can't find nginx.cluster.local: No answer
*** Can't find nginx.default.svc.cluster.local: No answer
*** Can't find nginx.svc.cluster.local: No answer
*** Can't find nginx.cluster.local: No answer

/ # wget nginx
Connecting to nginx (10.96.69.143:80)
index.html 100% |**********************************| 612 0:00:00 ETA
/ # wget -O - -q http://nginx:80/

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

这时已经解析成功，可以通过服务名ningx访问了。

为了测试是否成功，先删除pod试试看，看看在起来的pod是否能通过服务名访问。

[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client1 1/1 Running 0 18m
nginx-deploy-55d8d67cf-xdxcj 1/1 Running 0 57m

[root@master ~]# kubectl delete pods nginx-deploy-55d8d67cf-xdxcj
pod "nginx-deploy-55d8d67cf-xdxcj" deleted

[root@master ~]# kubectl get pods
NAME READY STATUS RESTARTS AGE
client1 1/1 Running 0 19m
nginx-deploy-55d8d67cf-9rm67 0/1 ContainerCreating 0 22s

这时新的pod已经创建成功了。通过临时客户端在去访问服务名看看是否能联通。

/ # wget -O - -q http://nginx:80/

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

发现还是可以发现。没有问题。

[root@master ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 443/TCP 3d
nginx ClusterIP 10.96.69.143 80/TCP 43m

[root@master ~]# kubectl describe svc nginx
Name:　　nginx
Namespace:　　default
Labels: 　　 run=nginx-deploy
Annotations:　　
Selector: 　　 run=nginx-deploy
Type: 　　 ClusterIP
IP: 　　 10.96.69.143
Port:　　 80/TCP
TargetPort: 　　 80/TCP
Endpoints:　　 10.244.2.3:80
Session Affinity:　　 None
Events:　　

[root@master ~]# kubectl get pods --show-labels
NAME READY STATUS RESTARTS AGE LABELS
client1 1/1 Running 0 27m run=client1
nginx-deploy-55d8d67cf-9rm67 1/1 Running 0 8m18s pod-template-hash=55d8d67cf,run=nginx-deploy

可以得出结论是根据标签选中的，而不是根据IP地址选中的。

删除服务以后，在从新起个服务，发现客户端还是能直接发现nginx服务的。
[root@master ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 443/TCP 3d1h
nginx ClusterIP 10.96.69.143 80/TCP 58m
[root@master ~]# kubectl delete svc nginx
service "nginx" deleted
[root@master ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 443/TCP 3d1h
[root@master ~]# kubectl expose deployment nginx-deploy --name=nginx
service/nginx exposed
[root@master ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 443/TCP 3d1h
nginx ClusterIP 10.104.156.118 80/TCP 7s

/ # wget -O - -q http://nginx:80/

Welcome to nginx!

If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.

For online documentation and support please refer to
nginx.org.

Commercial support is available at
nginx.com.

Thank you for using nginx.

只要服务在，就可以正确的反应到DNS上的。

查看控制器的详细信息：

[root@master ~]# kubectl describe deployment nginx-deploy
Name: 　　 nginx-deploy
Namespace:　　 default
CreationTimestamp:　　 Thu, 16 May 2019 08:41:11 +0800
Labels:　　 run=nginx-deploy
Annotations: 　　 deployment.kubernetes.io/revision: 1
Selector: 　　 run=nginx-deploy
Replicas: 　　 1 desired | 1 updated | 1 total | 1 available | 0 unavailable
StrategyType:　　 RollingUpdate
MinReadySeconds: 　　 0
RollingUpdateStrategy: 　　 25% max unavailable, 25% max surge
Pod Template:
  Labels: 　　 run=nginx-deploy
  Containers:
   nginx-deploy:
　Image: 　　 nginx:1.14-alpine
　Port:　　 80/TCP
　Host Port:　　 0/TCP
　Environment: 　　
　Mounts: 　　
  Volumes:　　
Conditions:
　Type Status Reason
　---- ------ ------
　Progressing True NewReplicaSetAvailable
　Available True MinimumReplicasAvailable
OldReplicaSets:
NewReplicaSet: nginx-deploy-55d8d67cf (1/1 replicas created)
Events:

 

 -w 表示监控进度

 

 pod也是可以动态扩展的。当然也可以动态缩减，直接修改要改成的几，例如像缩减成3个。就把下面图片的改成 --replicas=3 就可以了

 

动态升级：

[root@master ~]# kubectl set image -h
Usage:
  kubectl set image (-f FILENAME | TYPE NAME) CONTAINER_NAME_1=CONTAINER_IMAGE_1
  ... CONTAINER_NAME_N=CONTAINER_IMAGE_N [options]

TYPE NAME 表示哪个pod
CONTAINER_NAME_1=CONTAINER_IMAGE_1 表示哪个容器替换成哪个镜像

比如像替换myapp-848b5b879b-gxxtc容器

通过kubectl describe pods 可以查看容器的各种信息，包括容器名字等等。

 

 

 

 

把v1版本升级成v2版本。第一个myapp是控制器的名字，第二个myapp是容器名

kubectl rollout status deployment myapp 可以查看更新的过程。

使用上面的命令在查看就可以看到是v2版本了。

也可以进行回滚操作：

kubectl rollout undo deployment myapp 回滚的时候可以指定回滚到哪个版本。不指定就默认回滚到上个版本。

如果想集群外部访问nginx的话，只需要修改service类型为NodeProt即可。

[root@master ~]# kubectl edit svc nginx
metadata:
  creationTimestamp: "2019-05-16T02:02:30Z"
  labels:
    run: nginx-deploy
  name: nginx
  namespace: default
  resourceVersion: "51839"
  selfLink: /api/v1/namespaces/default/services/nginx
  uid: a94b9787-777e-11e9-833b-000c29ac207f
spec:
  clusterIP: 10.104.156.118
  externalTrafficPolicy: Cluster
  ports:
  - nodePort: 31998
    port: 80
    protocol: TCP
    targetPort: 80
  selector:
    run: nginx-deploy
  sessionAffinity: None
  type: NodePort //这里修改成NodePort就可以外部访问了
status:
  loadBalancer: {}

[root@master ~]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 443/TCP 3d2h
nginx NodePort 10.104.156.118 80:31998/TCP 67m

可以看到了多了一个端口。这个端口就是外部访问的端口

 

可以看到通过浏览器访问node2节点的IP地址和31998端口号就可以外部进行访问nginx了。 

转载于:https://www.cnblogs.com/green-frog-2019/p/11528181.html