Building a Simple Database Server in a Container

Using MariaDB, you can set up a basic database in a container that can be accessed by other applications. The procedure in this document does the following:

• Builds a MariaDB database server inside a docker formatted container
• Exposes the service on port 3306 of the host
• Starts up the database service to share a few pieces of information
• Allows a script from Web server to query the database (needs additional Web server container from here)
• Offers tips on how to use and extend this container

Creating and running the MariaDB Database Server Container

1. Install system: Install a Red Hat Enterprise Linux 7 or Red Hat Enterprise Linux Atomic Host system that includes the docker package and start the docker service. See Get Started with Docker Containers for details.

2. Pull image: Pull the rhel7 image by typing the following:

   # docker pull rhel7:latest
   

3. Get tarball with supporting files: Download the tarball file attached to this article (mariadb_cont*.tgz), download it to a new mydbcontainer directory, and untar it as follows:

   # mkdir ~/mydbcontainer
   # cp mariadb_cont*.tgz ~/mydbcontainer
   # cd ~/mydbcontainer
   # tar xvf mariadb_cont*.tgz
   gss_db.sql
   Dockerfile
   

4. Check the Dockerfile: Modify the Dockerfile file in the ~/mydbcontainer directory as needed (perhaps only modify Maintainer_Name to add your name). Here are the contents of that file:

   # Database container with simple data for a Web application
   # Using RHEL 7 base image and MariahDB database
   # Version 1
   
   # Pull the rhel image from the local repository
   FROM rhel7:latest
   USER root
   
   MAINTAINER Maintainer_Name
   
   # Update image
   RUN yum update -y
   
   # Add Mariahdb software
   RUN yum -y install mariadb-server
   
   # Set up Mariahdb database
   ADD gss_db.sql /tmp/gss_db.sql
   RUN /usr/libexec/mariadb-prepare-db-dir
   RUN /usr/bin/mysqld_safe --basedir=/usr & \
       sleep 10s && \
    /usr/bin/mysqladmin -u root password 'redhat' && \
       mysql --user=root --password=redhat < /tmp/gss_db.sql && \
       mysqladmin shutdown --password=redhat
   
   # Expose Mysql port 3306
   EXPOSE 3306
   
   # Start the service
   CMD ["--basedir=/usr"]
   ENTRYPOINT ["/usr/bin/mysqld_safe"]
   

5. Build database server container: From the directory containing the Dockerfile file and other content, type the following:

   # docker build -t dbforweb .
   Sending build context to Docker daemon 528.4 kB
   Sending build context to Docker daemon
   Step 0 : FROM rhel7:latest
    ---> bef54b8f8a2f
   Step 1 : USER root
   ...
   

6. Start the database server container: To start the container image, run the following command:

   # docker run -d -p 3306:3306 --name=mydbforweb dbforweb
   

7. Test the database server container: Assuming the docker0 interface on the host is 172.17.42.1 (yours may be different), check that the database container is operational by running the nc command (in RHEL 7, type yum install nc to get it) as shown here:

   # nc -v 172.17.42.1 3306
   Ncat: Version 6.40 ( http://nmap.org/ncat )
   Ncat: Connected to 172.17.42.1:3306.
   R
   5.5.40-MariaDB?acL3YF31?X?FWbiiTIO2Kd6mysql_native_password Ctrl-C
   

Tips for this container

Here are some tips to help you use the Web Server container:

• Adding your own database: You can include your own MariaDB content by copying your database file to the build directory and changing the name of the database file from gss_db.sql to the name of your database (in several places in the Dockerfile file).

• Orchestrate containers: A better way to manage this container with other containers is to use Kubernetes to orchestrate them into pods. See Get Started Orchestrating Docker Containers with Kubernetes for a description of how to get started using Kubernetes.