Unable to Connect MySQL container to Tomcat Container in docker

The Plan

I want my tomcat server to be able to connect to my MySQL server both in separate containers.

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  • The Problem

    Tomcat cannot connect to MySQL

    I used some of the details from the wordpress tutorial about setting up a link with the mysql container and created the link to the MySQL.

    Although the tomcat and mysql spin up just fine I can’t seem to get tomcat to be able to connect to MySQL, the settings work on my local machine perfectly fine.

    I’ve attempted to use --net: "host" as well although that does not work with Tomcat as it throws a severe error.

    Previous answers

    I noticed on this post a load of possible fixes for the error although I don’t believe any of these would translate to my problem as I believe this is a docker problem not a host one.

    docker-compose.yml

    web:
      image: tomcat:7.0
      container_name: tomcat-container
      ports:
       - "80:8080"
      hostname: docker-tomcat
      volumes:
       - /home/webapps:/usr/local/tomcat/webapps
      links:
       - db
    db:
      image: mysql
      container_name: mysql-container
      environment:
       MYSQL_ROOT_PASSWORD: Mysqlpassword1
       MYSQL_DATABASE: tracker
      volumes:
       - /home/mysqlDB:/var/lib/mysql
    

    This is my Context.xml from tomcat.

    <Context>
        <Resource
            name="jdbc/tracker" type="javax.sql.DataSource"
            maxActive="100" maxIdle="30" maxWait="10000" 
            url="jdbc:mysql://localhost:3306/tracker?useSSL=false"
            driverClassName="com.mysql.jdbc.Driver"
            username="root" password="mysqladmin1"
        />
        <Resource
            name="jdbc/jenkins" type="javax.sql.DataSource"
            maxActive="100" maxIdle="30" maxWait="10000" 
            url="jdbc:mysql://localhost:3306/jenkins?useSSL=false"
            driverClassName="com.mysql.jdbc.Driver"
            username="root" password="mysqladmin1"
        />
    </Context>
    

    The error code.

    The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:1549)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1388)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
    at databaseConnections.SQLDatabaseConnection.tableExists(SQLDatabaseConnection.java:131)
    at databaseConnections.JiraSQLDatabaseConnection.<init>(JiraSQLDatabaseConnection.java:50)
    

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  • One Solution collect form web for “Unable to Connect MySQL container to Tomcat Container in docker”

    As you’re linking db as “db”, you cannot use localhost to join you database. you should “db”

    jdbc:mysql://db:3306/tracker?useSSL=false
    

    In your container, localhost design your tomcat container, not your host. MySQL container has his own network.

    Futhermore, if you don’t like “db” name, you can name link it with different name

    For exemple:

     links:
       - db:container-mysql
    

    In this case, inside you tomcat container, you could use

    jdbc:mysql://container-mysql:3306/tracker?useSSL=false
    
    Docker will be the best open platform for developers and sysadmins to build, ship, and run distributed applications.