概述

由于Pod和Service都是k8s集群范围内的虚拟概念，所有集群外的客户端系统无法通过Pod的IP或者Service的虚拟IP和端口访问它们。为了让外部客户端访问这些服务，可以将Pod和Service的端口号映射到宿主机，以使客户端应用能通过物理机访问容器应用。

将容器应用的端口号映射到物理机

通过设置容器级别的hostPort，将容器应用的端口号映射到物理机上

apiVersion: v1
kind: Pod
metadata:
  name: webapp
  labels:
    app: webapp
spec:
  containers:
  - name: webapp
    image: tomcat
    ports:
    - containerPort: 8080
      hostPort: 8081

创建并查看结果

[root@master1 service]# kubectl apply -f 09.yaml
pod/webapp created

[root@master1 service]# kubectl get pod
NAME     READY   STATUS    RESTARTS   AGE
webapp   1/1     Running   0          4m2s

通过物理地址的IP和8081端口访问Pod的容器服务

<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 404 – Not Found</h1><hr class="line" /><p><b>Type</b> Status Report</p><p><b>Description</b> The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.</p><hr class="line" /><h3>Apache Tomcat/10.0.14</h3></body></html>

通过设置Pod级别的hostNetwork=true

该Pod中所有容器的端口都将被直接映射到物理机上。在设置hostNetwork=true时需要注意，在容器的Ports定义部分如果不指定hostPort，则默认hostPort等于containerPort，如果指定了hostPort，则hostPort必须等于containerPort的值

apiVersion: v1
kind: Pod
metadata:
  name: webapp
  labels:
    app: webapp
spec:
  hostNetwork: true
  containers:
  - name: webapp
    image: tomcat
    imagePullPolicy: Never
    ports:
    - containerPort: 8080

运行并查看结果

[root@master1 service]# kubectl apply -f 10.yaml
pod/webapp created

[root@master1 service]# kubectl get pod -o wide
NAME     READY   STATUS    RESTARTS   AGE    IP               NODE    NOMINATED NODE   READINESS GATES
webapp   1/1     Running   0          5m8s   192.168.40.182   node1   <none>           <none>

访问

<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 404 – Not Found</h1><hr class="line" /><p><b>Type</b> Status Report</p><p><b>Description</b> The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.</p><hr class="line" /><h3>Apache Tomcat/10.0.14</h3></body></html>

将`Service`映射到物理机

通过设置nodePort映射到物理机

示例Pod

apiVersion: v1
kind: Pod
metadata:
  name: webapp
  labels:
    app: webapp
spec:
  containers:
  - name: webapp
    image: tomcat
    imagePullPolicy: Never
    ports:
    - containerPort: 8080

创建Service

apiVersion: v1
kind: Service
metadata:
  name: webapp
spec:
  type: NodePort
  ports:
  - port: 8080
    targetPort: 8080
    nodePort: 30660
  selector:
    app: webapp

创建并查询结果

[root@master1 service]# kubectl get svc -o wide
NAME     TYPE       CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE   SELECTOR
webapp   NodePort   10.10.157.91   <none>        8080:30660/TCP   54s   app=webapp

通过宿主机+端口访问

curl 192.168.40.180:30660

<!doctype html><html lang="en"><head><title>HTTP Status 404 – Not Found</title><style type="text/css">body {font-family:Tahoma,Arial,sans-serif;} h1, h2, h3, b {color:white;background-color:#525D76;} h1 {font-size:22px;} h2 {font-size:16px;} h3 {font-size:14px;} p {font-size:12px;} a {color:black;} .line {height:1px;background-color:#525D76;border:none;}</style></head><body><h1>HTTP Status 404 – Not Found</h1><hr class="line" /><p><b>Type</b> Status Report</p><p><b>Description</b> The origin server did not find a current representation for the target resource or is not willing to disclose that one exists.</p><hr class="line" /><h3>Apache Tomcat/10.0.14</h3></body></html>

kubernetes Service-03 从集群外访问Pod或者Service

概述

将容器应用的端口号映射到物理机

将Service映射到物理机

将`Service`映射到物理机