Kubernetes m6S之Pod跨namespace名称空间访问Service服务

 

Kubernetes的两个Service（ServiceA、ServiceB）和对应的Pod（PodA、PodB）分别属于不同的namespace名称空间，现需要PodA和PodB跨namespace名称空间并通过Service实现互访。应该如何实现？

 

场景需求

Kubernetes的两个Service（ServiceA、ServiceB）和对应的Pod（PodA、PodB）分别属于不同的namespace名称空间，现需要PodA和PodB跨namespace名称空间并通过Service实现互访。如何实现？

说明：这里是指通过Service的Name进行通信访问，而不是通过Service的IP【因因为每次重启Service，NAME不会改变，而IP是会改变的】。

 

主机配置规划

服务器名称(hostname)系统版本配置内网IP外网IP(模拟)
k8s-masterCentOS7.72C/4G/20G172.16.1.11010.0.0.110
k8s-node01CentOS7.72C/4G/20G172.16.1.11110.0.0.111
k8s-node02CentOS7.72C/4G/20G172.16.1.11210.0.0.112

 

创建Service和Pod

相关yaml文件

 1 [root@k8s-master cross_ns]# pwd
 2 /root/k8s_practice/cross_ns
 3 [root@k8s-master cross_ns]#
 4 [root@k8s-master cross_ns]# cat deply_service_myns.yaml
 5apiVersion: v1
 6kind: Namespace
 7metadata:
 8  name: myns
 9 ---
10 apiVersion: apps/v1
11kind: Deployment
12metadata:
13   name: myapp-deploy1
14  namespace: myns
15spec:
16   replicas: 2
17  selector:
18    matchLabels:
19      app: myapp
20      release: v1
21  template:
22    metadata:
23      labels:
24        app: myapp
25        release: v1
26    spec:
27      containers:
28       - name: myapp
29         image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1
30        imagePullPolicy: IfNotPresent
31        ports:
32         - name: http
33           containerPort: 80
34 ---
35apiVersion: v1
36kind: Service
37metadata:
38   name: myapp-clusterip1
39  namespace: myns
40spec:
41  type: ClusterIP  # 默认类型
42  selector:
43    app: myapp
44    release: v1
45  ports:
46   - name: http
47     port: 80
48     targetPort: 80
49
50 [root@k8s-master cross_ns]#
51 [root@k8s-master cross_ns]# cat deply_service_mytest.yaml
52apiVersion: v1
53kind: Namespace
54metadata:
55  name: mytest
56 ---
57 apiVersion: apps/v1
58kind: Deployment
59metadata:
60   name: myapp-deploy2
61  namespace: mytest
62spec:
63   replicas: 2
64  selector:
65    matchLabels:
66      app: myapp
67      release: v2
68  template:
69    metadata:
70      labels:
71        app: myapp
72        release: v2
73    spec:
74      containers:
75       - name: myapp
76         image: registry.cn-beijing.aliyuncs.com/google_registry/myapp:v2
77        imagePullPolicy: IfNotPresent
78        ports:
79         - name: http
80           containerPort: 80
81 ---
82apiVersion: v1
83kind: Service
84metadata:
85   name: myapp-clusterip2
86  namespace: mytest
87spec:
88  type: ClusterIP  # 默认类型
89  selector:
90    app: myapp
91    release: v2
92  ports:
93   - name: http
94     port: 80
95     targetPort: 80

 

运行yaml文件

1 kubectl apply -f deply_service_myns.yaml
2 kubectl apply -f deply_service_mytest.yaml

 

查看myns名称空间信息

 1 [root@k8s-master cross_ns]# kubectl get svc -n myns -o wide
 2 NAME               TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE   SELECTOR
 3 myapp-clusterip1   ClusterIP   10.100.61.11   <none>        80/TCP    3m    app=myapp,release=v1
 4 [root@k8s-master cross_ns]#
 5 [root@k8s-master cross_ns]# kubectl get deploy -n myns -o wide
 6 NAME            READY   UP-TO-DATE   AVAILABLE   AGE    CONTAINERS   IMAGES                                                      SELECTOR
 7 myapp-deploy1   2/222           3m7s   myapp        registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp,release=v1
 8 [root@k8s-master cross_ns]#
 9 [root@k8s-master cross_ns]# kubectl get rs -n myns -o wide
10NAME                       DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES                                                      SELECTOR
11 myapp-deploy1-5b9d78576c   222       3m15s   myapp        registry.cn-beijing.aliyuncs.com/google_registry/myapp:v1   app=myapp,pod-template-hash=5b9d78576c,release=v1
12 [root@k8s-master cross_ns]#
13 [root@k8s-master cross_ns]# kubectl get pod -n myns -o wide
14NAME                             READY   STATUS    RESTARTS   AGE     IP             NODE         NOMINATED NODE   READINESS GATES
15 myapp-deploy1-5b9d78576c-wfw4n   1/1     Running   0          3m20s   10.244.2.136   k8s-node02   <none>           <none>
16 myapp-deploy1-5b9d78576c-zsfjl   1/1     Running   0          3m20s   10.244.3.193   k8s-node01   <none>           <none>

 

查看mytest名称空间信息

 1 [root@k8s-master cross_ns]# kubectl get svc -n mytest -o wide
 2 NAME               TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE    SELECTOR
 3 myapp-clusterip2   ClusterIP   10.100.201.103   <none>        80/TCP    4m9s   app=myapp,release=v2
 4 [root@k8s-master cross_ns]#
 5 [root@k8s-master cross_ns]# kubectl get deploy -n mytest -o wide
 6 NAME            READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS   IMAGES                                                      SELECTOR
 7 myapp-deploy2   2/222           4m15s   myapp        registry.cn-beijing.aliyuncs.com/google_registry/myapp:v2   app=myapp,release=v2
 8 [root@k8s-master cross_ns]#
 9 [root@k8s-master cross_ns]# kubectl get rs -n mytest -o wide
10NAME                      DESIRED   CURRENT   READY   AGE     CONTAINERS   IMAGES                                                      SELECTOR
11 myapp-deploy2-dc8f96497   222       4m22s   myapp        registry.cn-beijing.aliyuncs.com/google_registry/myapp:v2   app=myapp,pod-template-hash=dc8f96497,release=v2
12 [root@k8s-master cross_ns]#
13 [root@k8s-master cross_ns]# kubectl get pod -n mytest -o wide
14NAME                            READY   STATUS    RESTARTS   AGE     IP             NODE         NOMINATED NODE   READINESS GATES
15 myapp-deploy2-dc8f96497-nnkqn   1/1     Running   0          4m27s   10.244.3.194   k8s-node01   <none>           <none>
16 myapp-deploy2-dc8f96497-w47dt   1/1     Running   0          4m27s   10.244.2.137   k8s-node02   <none>           <none>

 

只看Service和Pod

 1 [root@k8s-master cross_ns]# kubectl get pod -A -o wide | grep -E '(my)|(NAME)'
 2NAMESPACE              NAME                                         READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
 3 myns                   myapp-deploy1-5b9d78576c-wfw4n               1/1     Running   0          41m   10.244.2.136   k8s-node02   <none>           <none>
 4 myns                   myapp-deploy1-5b9d78576c-zsfjl               1/1     Running   0          41m   10.244.3.193   k8s-node01   <none>           <none>
 5 mytest                 myapp-deploy2-dc8f96497-nnkqn                1/1     Running   0          41m   10.244.3.194   k8s-node01   <none>           <none>
 6 mytest                 myapp-deploy2-dc8f96497-w47dt                1/1     Running   0          41m   10.244.2.137   k8s-node02   <none>           <none>
 7 [root@k8s-master cross_ns]#
 8 [root@k8s-master cross_ns]#
 9 [root@k8s-master cross_ns]# kubectl get svc -A -o wide | grep -E '(my)|(NAME)'
10 NAMESPACE              NAME                        TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                  AGE   SELECTOR
11 myns                   myapp-clusterip1            ClusterIP   10.100.61.11     <none>        80/TCP                   41m   app=myapp,release=v1
12 mytest                 myapp-clusterip2            ClusterIP   10.100.201.103   <none>        80/TCP                   41m   app=myapp,release=v2

 

pod跨名称空间namespace与Service通信

说明：是通过Service的NAME进行通信，而不是Service的IP【因为每次重启Service，NAME不会改变，而IP是会改变的】。

 

 1# 进入ns名称空间下的一个Pod容器
 2 [root@k8s-master cross_ns]# kubectl exec -it -n myns myapp-deploy1-5b9d78576c-wfw4n sh
 3 / # cd /root/
 4### 如下说明在同一名称空间下，通信无问题
 5 ~ # ping myapp-clusterip1
 6 PING myapp-clusterip1 (10.100.61.11): 56 data bytes
 764 bytes from 10.100.61.11: seq=0 ttl=64time=0.046 ms
 864 bytes from 10.100.61.11: seq=1 ttl=64time=0.081 ms
 9 ~ #
10 ~ # wget myapp-clusterip1 -O myns.html
11 Connecting to myapp-clusterip1 (10.100.61.11:80)
12 myns.html            100%
13 ~ #
14 ~ # cat myns.html
15 Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
16
17### 如下说明在不同的名称空间下，通过Service的NAME进行通信存在问题
18 ~ # ping myapp-clusterip2
19ping: bad address 'myapp-clusterip2'
20 ~ #
21 ~ # wget myapp-clusterip2 -O mytest.html
22wget: bad address 'myapp-clusterip2'

 

 

实现跨namespace与Service通信

通过Service的ExternalName类型即可实现跨namespace名称空间与Service通信。

Service域名格式：$(service name).$(namespace).svc.cluster.local，其中 cluster.local 为指定的集群的域名

相关yaml文件

 1 [root@k8s-master cross_ns]# pwd
 2 /root/k8s_practice/cross_ns
 3 [root@k8s-master cross_ns]#
 4 [root@k8s-master cross_ns]# cat svc_ExternalName_visit.yaml
 5 # 实现 myns 名称空间的pod，访问 mytest 名称空间的Service：myapp-clusterip2
 6apiVersion: v1
 7kind: Service
 8metadata:
 9   name: myapp-clusterip1-externalname
10  namespace: myns
11spec:
12  type: ExternalName
13   externalName: myapp-clusterip2.mytest.svc.cluster.local
14  ports:
15   - name: http
16     port: 80
17     targetPort: 80
18 ---
19 # 实现 mytest 名称空间的Pod，访问 myns 名称空间的Service：myapp-clusterip1
20apiVersion: v1
21kind: Service
22metadata:
23   name: myapp-clusterip2-externalname
24  namespace: mytest
25spec:
26  type: ExternalName
27   externalName: myapp-clusterip1.myns.svc.cluster.local
28  ports:
29   - name: http
30     port: 80
31     targetPort: 80

 

运行yaml文件

1 [root@k8s-master cross_ns]# kubectl apply -f svc_ExternalName_visit.yaml
2 [root@k8s-master cross_ns]#
3 [root@k8s-master cross_ns]# kubectl get svc -A -o wide | grep -E '(ExternalName)|(NAME)'
4 NAMESPACE              NAME                            TYPE           CLUSTER-IP       EXTERNAL-IP                                 PORT(S)                  AGE   SELECTOR
5 myns                   myapp-clusterip1-externalname   ExternalName   <none>           myapp-clusterip2.mytest.svc.cluster.local   80/TCP                   28s   <none>
6 mytest                 myapp-clusterip2-externalname   ExternalName   <none>           myapp-clusterip1.myns.svc.cluster.local     80/TCP                   28s   <none>

 

pod跨名称空间namespace与Service通信

到目前所有service和pod信息查看

 1 [root@k8s-master cross_ns]# kubectl get svc -A -o wide | grep -E '(my)|(NAME)'
 2 NAMESPACE              NAME                            TYPE           CLUSTER-IP       EXTERNAL-IP                                 PORT(S)                  AGE   SELECTOR
 3 myns                   myapp-clusterip1                ClusterIP      10.100.61.11     <none>                                      80/TCP                   62m   app=myapp,release=v1
 4 myns                   myapp-clusterip1-externalname   ExternalName   <none>           myapp-clusterip2.mytest.svc.cluster.local   80/TCP                   84s   <none>
 5 mytest                 myapp-clusterip2                ClusterIP      10.100.201.103   <none>                                      80/TCP                   62m   app=myapp,release=v2
 6 mytest                 myapp-clusterip2-externalname   ExternalName   <none>           myapp-clusterip1.myns.svc.cluster.local     80/TCP                   84s   <none>
 7 [root@k8s-master cross_ns]#
 8 [root@k8s-master cross_ns]# kubectl get pod -A -o wide | grep -E '(my)|(NAME)'
 9NAMESPACE              NAME                                         READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
10 myns                   myapp-deploy1-5b9d78576c-wfw4n               1/1     Running   0          62m   10.244.2.136   k8s-node02   <none>           <none>
11 myns                   myapp-deploy1-5b9d78576c-zsfjl               1/1     Running   0          62m   10.244.3.193   k8s-node01   <none>           <none>
12 mytest                 myapp-deploy2-dc8f96497-nnkqn                1/1     Running   0          62m   10.244.3.194   k8s-node01   <none>           <none>
13 mytest                 myapp-deploy2-dc8f96497-w47dt                1/1     Running   0          62m   10.244.2.137   k8s-node02   <none>           <none>

 

myns 名称空间的pod，访问 mytest 名称空间的Service：myapp-clusterip2

 1 [root@k8s-master cross_ns]# kubectl exec -it -n myns myapp-deploy1-5b9d78576c-wfw4n sh
 2 / # cd /root/
 3### 如下说明在同一名称空间下，通信无问题
 4 ~ # ping myapp-clusterip1
 5 PING myapp-clusterip1 (10.100.61.11): 56 data bytes
 664 bytes from 10.100.61.11: seq=0 ttl=64time=0.057 ms
 764 bytes from 10.100.61.11: seq=1 ttl=64time=0.071 ms
 8………………
 9 ~ #
10 ~ # wget myapp-clusterip1 -O myns.html
11 Connecting to myapp-clusterip1 (10.100.61.11:80)
12 myns.html            100%
13 ~ #
14 ~ # cat myns.html
15 Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>
16
17### 如下说明通过Service externalname类型，实现了Pod跨namespace名称空间与Service访问
18 ~ # ping myapp-clusterip1-externalname
19 PING myapp-clusterip1-externalname (10.100.201.103): 56 data bytes
2064 bytes from 10.100.201.103: seq=0 ttl=64time=0.050 ms
2164 bytes from 10.100.201.103: seq=1 ttl=64time=0.311 ms
22………………
23 ~ #
24 ~ # wget myapp-clusterip1-externalname -O mytest.html
25 Connecting to myapp-clusterip1-externalname (10.100.201.103:80)
26 mytest.html          100%
27 ~ #
28 ~ # cat mytest.html
29 Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

 

mytest 名称空间的Pod，访问 myns 名称空间的Service：myapp-clusterip1

 1 [root@k8s-master cross_ns]# kubectl exec -it -n mytest myapp-deploy2-dc8f96497-w47dt sh
 2 / # cd /root/
 3### 如下说明在同一名称空间下，通信无问题
 4 ~ # ping myapp-clusterip2
 5 PING myapp-clusterip2 (10.100.201.103): 56 data bytes
 664 bytes from 10.100.201.103: seq=0 ttl=64time=0.087 ms
 764 bytes from 10.100.201.103: seq=1 ttl=64time=0.073 ms
 8………………
 9 ~ #
10 ~ # wget myapp-clusterip2 -O mytest.html
11 Connecting to myapp-clusterip2 (10.100.201.103:80)
12 mytest.html          100%
13 ~ #
14 ~ # cat mytest.html
15 Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
16
17### 如下说明通过Service externalname类型，实现了Pod跨namespace名称空间与Service访问
18 ~ # ping myapp-clusterip2-externalname
19 PING myapp-clusterip2-externalname (10.100.61.11): 56 data bytes
2064 bytes from 10.100.61.11: seq=0 ttl=64time=0.089 ms
2164 bytes from 10.100.61.11: seq=1 ttl=64time=0.071 ms
22………………
23 ~ #
24 ~ # wget myapp-clusterip2-externalname -O myns.html
25 Connecting to myapp-clusterip2-externalname (10.100.61.11:80)
26 myns.html            100%
27 ~ #
28 ~ # cat myns.html
29 Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>

由上可见，实现了Pod跨namespace名称空间与Service访问。

 

完毕！

 

 

 

———END———
如果觉得不错就关注下呗 (-^O^-) ！

 

以上是 Kubernetes m6S之Pod跨namespace名称空间访问Service服务 的全部内容， 来源链接： utcz.com/a/48398.html

回到顶部