Kubernetes----ExternalName类型的Service

Kubernetes----ExternalName类型的Service

一、ExternalName类型Service简介

externalName Service是k8s中一个特殊的service类型，它不需要指定selector去选择哪些pods实例提供服务，而是使用DNS CNAME机制把自己CNAME到你指定的另外一个域名上，你可以提供集群内的名字，比如mysql.db.svc这样的建立在db命名空间内的mysql服务，也可以指定v1kind: Namespacemetadata: name: dev---apiVersion: v1kind: Servicemetadata: name: search namespace: devspec: type: ExternalName externalName:

使用如下命令创建资源

[root@master service]# kubectl apply -f external_name.yamlnamespace/dev createdservice/search created[root@master service]#

查看资源如下：

[root@master service]# kubectl get service -n devNAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGEsearch ExternalName baidu.com 11s[root@master service]#

此时，在集群内部的pod中就可以通过 search.dev.svc.cluster.local 访问baidu.com了 下面验证一下，首先登录一个pod查看 /etc/resolve.conf

[root@master service]# kubectl exec -it pod/pc-deployment-5ffc5bf56c-9bg6w -n dev /bin/bashkubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead.root@pc-deployment-5ffc5bf56c-9bg6w:/#root@pc-deployment-5ffc5bf56c-9bg6w:/# cat /etc/resolv.confnameserver 10.96.0.10search dev.svc.cluster.local svc.cluster.local cluster.localoptions ndots:5root@pc-deployment-5ffc5bf56c-9bg6w:/#

然后使用dig命令验证

[root@master service]# dig @10.96.0.10 search.dev.svc.cluster.local; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.9 <<>> @10.96.0.10 search.dev.svc.cluster.local; (1 server found);; global options: +cmd;; Got answer:;; WARNING: .local is reserved for Multicast DNS;; You are currently testing what happens when an mDNS query is leaked to DNS;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62861;; flags: qr aa rd; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1;; WARNING: recursion requested but not available;; OPT PSEUDOSECTION:; EDNS: version: 0, flags:; udp: 4096;; QUESTION SECTION:;search.dev.svc.cluster.local. IN A;; ANSWER SECTION:search.dev.svc.cluster.local. 30 IN CNAME baidu.com.baidu.com. 30 IN CNAME a.shifen.com.a.shifen.com. 30 IN A 110.242.68.3a.shifen.com. 30 IN A 110.242.68.4;; Query time: 5 msec;; SERVER: 10.96.0.10#53(10.96.0.10);; WHEN: Wed Apr 06 23:48:14 CST 2022;; MSG SIZE rcvd: 219[root@master service]#

三、删除资源

使用如下命令删除即可

[root@master service]# kubectl delete -f external_name.yamlnamespace "dev" deletedservice "search" deleted[root@master service]#

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