Step1:finish installing etcd and kubernetes with YUM in CentOS7 and shutdown firewall

Step2:modify related configuration item in /etc/sysconfig/docker

OPTIONS='--selinux-enabled=false --insecure-registry gcr.io'

Step3:modify related configuration item in /etc/kubernetes/apiserver

remove

ServiceAccount

in KUBE_ADMISSION_CONTROL configuration item

Step4:start all the related services of etcd and kubernetes

Step5:start ReplicationController for mysql db

kubectl create -f mysql-rc.yaml

apiVersion: v1
kind: ReplicationController  
metadata:
  name: mysql
spec:
  replicas: 1 
  selector:
    app: mysql
  template:
    metadata:
      labels:
        app: mysql
    spec:
      containers:
      - name: mysql
        image: hub.c.163.com/library/mysql
        ports:
        - containerPort: 3306
        env:
        - name: MYSQL_ROOT_PASSWORD
          value: "123456"

Step6:start related mysql db service

kubectl create -f mysql-svc.yaml

kind: Service   
metadata: 
  name: mysql 
spec:
  ports:
    - port: 3306
  selector:     
    app: mysql

Step7:start ReplicationController for myweb

kubectl create -f myweb-rc.yaml

apiVersion: v1
kind: ReplicationController
metadata:
  name: myweb
spec:
  replicas: 3  
  selector:
    app: myweb
  template:
    metadata:
      labels:
        app: myweb
    spec:
      containers:
      - name: myweb
        image: docker.io/kubeguide/tomcat-app:v1
        ports: 
        - containerPort: 8080
        env:
        - name: MYSQL_SERVICE_HOST
          value: "mysql"
        - name: MYSQL_SERVICE_PORT
          value: "3306"

Step8:start related tomcat service

kubectl create -f myweb-svc.yaml

apiVersion: v1
kind: Service
metadata: 
  name: myweb
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 30001
  selector:
    app: myweb

When I visit from browser with nodeport(30001),I get the following Exception:

Error:com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

kubectl get ep

NAME         ENDPOINTS                                         AGE

kubernetes   192.168.57.129:6443                               1d

mysql        172.17.0.2:3306                                   1d

myweb        172.17.0.3:8080,172.17.0.4:8080,172.17.0.5:8080   1d

kubectl get svc

NAME         CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE

kubernetes   10.254.0.1     <none>        443/TCP          1d

mysql        10.254.0.5     <none>        3306/TCP         1d

myweb        10.254.220.2   <nodes>       8080:30001/TCP   1d

From the interior of any tomcat container I can see the mysql env and the related mysql link code in JSP is as below:

Class.forName("com.mysql.jdbc.Driver");
String ip=System.getenv("MYSQL_SERVICE_HOST");
String port=System.getenv("MYSQL_SERVICE_PORT");
ip=(ip==null)?"localhost":ip;
port=(port==null)?"3306":port;  
System.out.println("Connecting to database...");

conn = java.sql.DriverManager.getConnection("jdbc:mysql://"+ip+":"+port+"?useUnicode=true&characterEncoding=UTF-8", "root","123456");

[root@promote ~]# docker exec -it 1470cfaa1b1c /bin/bash

root@myweb-xswfb:/usr/local/tomcat# env |grep MYSQL_SERVICE

MYSQL_SERVICE_PORT=3306

MYSQL_SERVICE_HOST=mysql

root@myweb-xswfb:/usr/local/tomcat# ping mysql

ping: unknown host

Can someone tell me why I could not ping mysqldb hostname from inner tomcat server?Or how to locate the problem further?