Kubernetes连接外部数据源

Kubernetes架构下比较核心的问题是数据如何persistance,虽然提供了Persistent volumn的方式，但是对于像数据库之类的产品在kubernetes集群环境中运行和管理还是很有难度的，Kubernetes提供了endpoints这种模式让外部的服务映射成内部的服务，这样比较好的解决了集群对外的连接问题，

如果我们去连接外部的一个oracle数据库，具体的步骤如下:

建立endpoints和service.

[root@k8s-master jdbcservice]# cat jdbc-endpoint.yaml 
apiVersion: v1
kind: Endpoints
metadata:
  name: jdbc
subsets:
  - addresses:
    - ip: 10.182.168.244
    ports:
    - port: 1521
      protocol: TCP

为了方便，我们固定了service的集群地址

[root@k8s-master jdbcservice]# cat jdbcservice.yaml 
apiVersion: v1
kind: Service
metadata:
  name: jdbc
spec:
  clusterIP: 10.254.150.201
  ports:
  - port: 1521
    targetPort: 1521
    protocol: TCP

需要注意的是，service和endpoints的名字要相同，另外如果delete了service.再重新建立的时候要再把endpoints建立一遍。

在这个service的表里，我们看到jdbc服务绑在了201这个地址上。

[root@k8s-master jdbcservice]# kubectl get services
NAME            CLUSTER-IP       EXTERNAL-IP   PORT(S)          AGE
helloworldsvc   10.254.43.122    <nodes>       7001:30001/TCP   12m
jdbc            10.254.150.201   <none>        1521/TCP         30m
kubernetes      10.254.0.1       <none>        443/TCP          121d
registry        10.254.174.54    <nodes>       5000:30002/TCP   20h

images的配置

然后对我们的weblogic images进行jdbc的配置。

点击Test Configuration,如果测试不过，weblogic不允许建立连接池成功.

在运行pod的节点上运行docker ps找到启动image的容器id.

[root@k8s-node-1 ~]# docker ps
CONTAINER ID        IMAGE                                                        COMMAND                  CREATED             STATUS              PORTS               NAMES
d2c1dc2a2cef        1213-helloworld:v1                                           "startWebLogic.sh"       7 minutes ago       Up 7 minutes                            k8s_weblogichelloworld.9efb3a79_helloworld-service-vfd10_default_6162d68a-9da9-11e7-b746-08002797edef_026d2cc4
85e04042041a        registry.access.redhat.com/rhel7/pod-infrastructure:latest   "/pod"                   7 minutes ago       Up 7 minutes                            k8s_POD.15c40ba1_helloworld-service-vfd10_default_6162d68a-9da9-11e7-b746-08002797edef_b59984a7
96acfd65eb3a        registry                                                     "/entrypoint.sh /etc/"   23 minutes ago      Up 23 minutes                           k8s_registry.71ab5625_registry-7nj8q_default_19ab0b7f-9cff-11e7-bf9d-08002797edef_fb5ae620
63652932256c        registry.access.redhat.com/rhel7/pod-infrastructure:latest   "/pod"                   23 minutes ago      Up 23 minutes                           k8s_POD.100f0b9e_registry-7nj8q_default_19ab0b7f-9cff-11e7-bf9d-08002797edef_98dd7f3f
1ed61c53625f        gcr.io/google_containers/etcd-amd64:2.2.1                    "/usr/local/bin/etcd "   47 minutes ago      Up 47 minutes                           k8s_etcd.bb974d90_kube-dns-v11-x0vr3_kube-system_5dd26461-3ef1-11e7-acf2-08002797edef_7316989c
fb8545a4aba4        gcr.io/google_containers/exechealthz:1.0                     "/exechealthz '-cmd=n"   47 minutes ago      Up 47 minutes                           k8s_healthz.525e4aad_kube-dns-v11-x0vr3_kube-system_5dd26461-3ef1-11e7-acf2-08002797edef_cec4d740
aa6c4caf3fa7        gcr.io/google_containers/skydns:2015-10-13-8c72f8c           "/skydns -machines=ht"   47 minutes ago      Up 47 minutes                           k8s_skydns.96837166_kube-dns-v11-x0vr3_kube-system_5dd26461-3ef1-11e7-acf2-08002797edef_5da89b81
5930dae5b843        registry.access.redhat.com/rhel7/pod-infrastructure:latest   "/pod"                   47 minutes ago      Up 47 minutes                           k8s_POD.4efc54ff_kube-dns-v11-x0vr3_kube-system_5dd26461-3ef1-11e7-acf2-08002797edef_3e3af088

生成新的images

[root@k8s-node-1 ~]# docker commit -m "jdbc" -a "ericnie" d2c1dc2a2cef 1213-helloworld-jdbc:v1
sha256:953e124483d2bcc03b3f46c8e6d935e3746634d78942cc477e31888c8d569171