kubernetes学习-Service（七）

一、Service-pod-endpoint关系

# 查看endpoints
[root@k8s-master deployments]# kubectl get endpoints
NAME         ENDPOINTS                          AGE
kubernetes   192.168.129.136:6443               90m
nginx-svc    10.109.131.1:80,10.111.156.65:80   22m
# 查看svc
[root@k8s-master deployments]# kubectl get svc
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP        90m
nginx-svc    NodePort    10.98.220.155   <none>        80:31662/TCP   22m[root@k8s-master deployments]# kubectl get po -l app=nginx-deploy -o wide
NAME                            READY   STATUS    RESTARTS   AGE   IP              NODE        NOMINATED NODE   READINESS GATES
nginx-deploy-86c5776ccd-grc2c   1/1     Running   0          46m   10.109.131.1    k8s-node2   <none>           <none>
nginx-deploy-86c5776ccd-kplgd   1/1     Running   0          47m   10.111.156.65   k8s-node1   <none>           <none>
[root@k8s-master deployments]# kubectl get ep
NAME         ENDPOINTS                          AGE
kubernetes   192.168.129.136:6443               94m
nginx-svc    10.109.131.1:80,10.111.156.65:80   25m可以看到endpoints中的名字和svc的名字是一样的，并且在endpoints中有两个IP地址分别为：
10.109.131.1:80
10.111.156.65:80,
同时，在po中看到，
nginx-deploy-86c5776ccd-grc2c对应10.109.131.1
nginx-deploy-86c5776ccd-kplgd对应10.111.156.65

Service，Pod，Endpoint之间的关系

二、Service定义

（1）配置文件

apiVersion: v1
kind: Service
metadata:name: nginx-svclabels:app: nginx-svc
spec:ports:- name: http # service 端口配置的名称protocol: TCP # 端口绑定的协议，支持 TCP、UDP、SCTP，默认为 TCPport: 80 # service 自己的端口targetPort: 9527 # 目标 pod 的端口- name: httpsport: 443protocol: TCPtargetPort: 443selector: # 选中当前 service 匹配哪些 pod，对哪些 pod 的东西流量进行代理app: nginx

（2）常用命令

# 创建 service
kubectl create -f nginx-svc.yaml# 查看 service 信息，通过 service 的 cluster ip 进行访问
kubectl get svc # 查看 pod 信息，通过 pod 的 ip 进行访问
kubectl get po -owide# 创建其他 pod 通过 service name 进行访问（推荐）
kubectl exec -it busybox -- sh
curl http://nginx-svc# 默认在当前 namespace 中访问，如果需要跨 namespace 访问 pod，则在 service name 后面加上 .<namespace> 即可
curl http://nginx-svc.default

（3）访问测试

# 创建一个busybox，并进入容器，如果之前已经创建了，则直接进入：kubectl exec -it dns-test -- sh
[root@k8s-master www]# kubectl run -it --image busybox dns-test --restart=Never --rm /bin/sh
If you don't see a command prompt, try pressing enter.
/ # wget http://nginx-svc  // 使用wget访问服务名
Connecting to nginx-svc (10.98.220.155:80)
saving to 'index.html'
index.html           100% |****************************************************************************************************************************************************************************************************************|   615  0:00:00 ETA
'index.html' saved
/ # cat index.html 
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>
/ # wget http://nginx-svc.default // 使用命名空间进行访问
Connecting to nginx-svc.default (10.98.220.155:80)
saving to 'index.html'
index.html           100% |****************************************************************************************************************************************************************************************************************|   615  0:00:00 ETA
'index.html' saved
/ # cat index.html 
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p><p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p><p><em>Thank you for using nginx.</em></p>
</body>
</html>

（4）代理 k8s 外部服务tong

[root@k8s-master services]# vim nginx-svc-external.yaml 
apiVersion: v1
kind: Service
metadata:name: nginx-svc-externallabels:app: nginx
spec:# selector: # 注释掉选择器，就不会自动创建endpoint#   app: nginx-deployports:- port: 80targetPort: 80name: webtype: ClusterIP[root@k8s-master services]# kubectl create -f nginx-svc-external.yaml 
service/nginx-svc-external created
# 可以看到svc被创建
[root@k8s-master services]# kubectl get svc
NAME                 TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE
kubernetes           ClusterIP   10.96.0.1       <none>        443/TCP        3d1h
nginx-svc            NodePort    10.98.220.155   <none>        80:31662/TCP   3d
nginx-svc-external   ClusterIP   10.110.50.51    <none>        80/TCP         2s# 但是endpoint没有被创建，因为没有指定selector
[root@k8s-master services]# kubectl get ep
NAME         ENDPOINTS                          AGE
kubernetes   192.168.129.136:6443               3d1h
nginx-svc    10.109.131.5:80,10.111.156.70:80   3d# 后面数据可能有变化，因为中间电脑重启过一次，重新搭建了一次环境
# 创建ep
[root@k8s-master services]# vim nginx-ep-external.yaml
apiVersion: v1
kind: Endpoints
metadata:labels:app: nginx  # 与 service 一致name: nginx-svc-external # 与 service 一致namespace: default # 与 service 一致
subsets:
- addresses:- ip: 120.78.159.117  # 目标 ip 地址ports: # 与 service 一致- name: webport: 80protocol: TCP[root@k8s-master services]# kubectl create -f nginx-ep-external.yaml 
endpoints/nginx-svc-external created
[root@k8s-master services]# kubectl get ep
NAME                 ENDPOINTS              AGE
kubernetes           192.168.129.136:6443   20m
nginx-svc-external   120.78.159.117:80      12s
# 查看代理信息
[root@k8s-master services]# kubectl describe ep nginx-svc-external
Name:         nginx-svc-external
Namespace:    default
Labels:       app=nginx
Annotations:  <none>
Subsets:Addresses:          120.78.159.117NotReadyAddresses:  <none>Ports:Name  Port  Protocol----  ----  --------web   80    TCPEvents:  <none>

通过service访问外部地址

# 进入到测试容器，我这里是因为之前电脑重启了，所以又重新建了一个
[root@k8s-master services]#  kubectl run -it --image busybox dns-test --restart=Never --rm /bin/sh
If you don't see a command prompt, try pressing enter.
/ # ls
bin    dev    etc    home   lib    lib64  proc   root   sys    tmp    usr    var
/ # wget http://nginx-svc-external  # 访问自己创建的service
Connecting to nginx-svc-external (10.96.11.222:80)
Connecting to www.wolfcode.cn (120.78.159.117:80) # 通过service访问到了外部地址
Connecting to www.wolfcode.cn (120.78.159.117:443)
wget: note: TLS certificate validation not implemented
saving to 'index.html'
index.html           100% |******************************************************************************************************************************************| 72518  0:00:00 ETA
'index.html' saved
/ # ls
bin         dev         etc         home        index.html  lib         lib64       proc        root        sys         tmp         usr         var
/ #

原理图如下：

（5）反向代理外部域名

[root@k8s-master services]# vim nginx-svc-externalname.yaml
apiVersion: v1
kind: Service
metadata:labels:app: wolfcode-external-domainname: wolfcode-external-domain
spec:type: ExternalNameexternalName: www.wolfcode.cn[root@k8s-master services]# kubectl create -f nginx-svc-externalname.yaml 
service/wolfcode-external-domain created
[root@k8s-master services]# kubectl get svc
NAME                       TYPE           CLUSTER-IP     EXTERNAL-IP       PORT(S)   AGE
kubernetes                 ClusterIP      10.96.0.1      <none>            443/TCP   68m
nginx-svc-external         ClusterIP      10.96.11.222   <none>            80/TCP    49m
wolfcode-external-domain   ExternalName   <none>         www.wolfcode.cn   <none>    10s# 通过域名的方式，访问外部服务
[root@k8s-master services]# kubectl run -it --image busybox dns-test --restart=Never --rm /bin/sh
If you don't see a command prompt, try pressing enter.
/ # wget wolfcode-external-domain  # 这里指定名字，上面的配置文件中externalName: www.wolfcode.cn，指定的是域名，而不是IP地址
Connecting to wolfcode-external-domain (120.78.159.117:80)
Connecting to www.wolfcode.cn (120.78.159.117:80)
Connecting to www.wolfcode.cn (120.78.159.117:443)
wget: note: TLS certificate validation not implemented
saving to 'index.html'
index.html           100% |******************************************************************************************************************************************| 72518  0:00:00 ETA
'index.html' saved# 查看目前配置的type 
[root@k8s-master services]# grep type nginx-svc.yaml type: NodePort
[root@k8s-master services]# grep type nginx-svc-external.yaml type: ClusterIP
[root@k8s-master services]# grep type nginx-svc-externalname.yaml type: ExternalName# 类型解释
ClusterIP：只能在集群内部使用，不配置类型的话默认就是 ClusterIP
ExternalName：返回定义的 CNAME 别名，可以配置为域名
NodePort：会在所有安装了 kube-proxy 的节点都绑定一个端口，此端口可以代理至对应的 Pod，集群外部可以使用任意节点 ip + NodePort 的端口号访问到集群中对应 Pod 中的服务。当类型设置为 NodePort 后，可以在 ports 配置中增加 nodePort 配置指定端口，需要在下方的端口范围内，如果不指定会随机指定端口端口范围：30000~32767端口范围配置在 /usr/lib/systemd/system/kube-apiserver.service 文件中LoadBalancer：使用云服务商（阿里云、腾讯云等）提供的负载均衡器服务