Docker

Deploy a tomcat application using docker-compose

Posted Nidhi Gupta

In this blog, we will learn what is docker-compose and how we can deploy a tomcat application which uses mysql database. We will learn how we can setup a development environment using docker-compose in a single command

If you want to see the video for this article, click here

Prerequisite:

  1. Docker and Docker-compose installed

INTRODUCTION

  • docker-compose is a tool which is used to deploy multi-container application. 
  • One single yaml file to deploy your application on the server.
  • Best suited for the developers to setup their workstation in a single command without installing any kind of dependencies for the application
  • docker-compose up to start your application 
  • docker-compose down to clean up all the docker containers

Let’s take an example here:

We have a project called user registration which uses mysql for storing the data . In terms of microservices, we can say that we have two services as shown below:

  • Web Service
  • Database Service

You can clone this git repo and try the below example

Explanation of docker-compose

  1. version : This is the version as per the docker engine you have installed on your machine 
  2. services: This is the main tag which is used to configure multiple services and under that we have details of all the services

 3. web: This is our service name -> using image, ports and volumes

4. volumes: To store the database files

Now we will create a docker-compose file which will together launch a tomcat, mysql and phpmyadmin container

Tomcat container — To run your application

Database container — To store the data

PhpMyAdmin — Access the database through GUI

So we will have three services

  1. db — we are using local path to store the data so that when you run docker-compose down all your data will retain. If you use the volume then all data will get lost if you run the docker-compose down

 Also, we are importing sql file so that our database is ready with the sample data. It is good so that each developer will always have the base or the actual data to run their application on the local machine

2. phpmyadmin — which is used to access the database through GUI and it depends on service db 

3. web — which is used to access your web application and it also depends on service db

version: '3.3'
services:
   db:
     image: mysql:5.7
     volumes:
       - /opt/test:/var/lib/mysql
       - ./mysql-dump:/docker-entrypoint-initdb.d
     environment:
       MYSQL_ROOT_PASSWORD: root
       MYSQL_DATABASE: testdb1
       MYSQL_USER: testuser
       MYSQL_PASSWORD: root
     ports:
       - 3306:3306
phpmyadmin:
    depends_on:
      - db
    image: phpmyadmin/phpmyadmin
    ports:
      - '8081:80'
    environment:
      PMA_HOST: db
      MYSQL_ROOT_PASSWORD: root
web:
    depends_on:
      - db
    image: tomcat
    volumes:
      - ./target/LoginWebApp-1.war:/usr/local/tomcat/webapps/LoginWebApp-1.war
    ports:
      - '8082:8080'
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: testdb1
      MYSQL_USER: testuser
      MYSQL_PASSWORD: root

Run the command

docker-compose up -d

All the environment variables which we are passing like mysql database details for the tomcat container can be used in the code.

You can now browse the url

http://yourip:8082/LoginWebApp-1/

Click on register and fill the below details and then check the database it has inserted all the values in USER table. This shows that tomcat application is able to make a database connection.

Create a tomcat container using docker-compose

version: '3'
services:
  web:
    image: tomcat
    ports:
      - "8081:8080"
    volumes:
      - ./index.html:/usr/local/tomcat/webapps/test/index.html

Now you can run this compose file in detached mode and can see the output “Server startup” at the end:

docker-compose -f docker-compose_tomcat.yml up -d

Now if you try to access it using http://yourip:8081, you will see the below error. You are getting this error because webapps folder is empty . There is no sample example folder is present.

But as we have put the index.html we can try to access that

http://yourip:8081/test

You should be able to see the content of your index.html.

This shows that we have successfully launched tomcat inside a docker container using docker-compose.

Clean the docker container

docker-compose -f docker-compose_tomcat.yml down

Install Mysql

  1. Now we will use the mysql image and launch a container
  2. This will create a volume on your docker machine and all data will be removed if you delete the container .
  3. You need to declare db_data1 in volume section at the bottom. 
version: '3.3'
services:
   db:
     image: mysql:5.7
     volumes:
       - db_data1:/var/lib/mysql
     environment:
       MYSQL_ROOT_PASSWORD: root
       MYSQL_DATABASE: testdb1
       MYSQL_USER: testuser
       MYSQL_PASSWORD: root
     ports:
       - 3306:3306
volumes:
    db_data1:
           name: db_data1

Now run this

docker-compose -f docker-compose_mysql.yml up -d

As you can see all mysql db details are created inside a container if you use the volume approach

How to connect using command prompt

mysql -utestuser -proot1 -h 127.0.0.1

Tear down container and volumes

# To Tear Down$ 
docker-compose down --volumes

Install Mysql with phpadmin so that we can access the database through GUI

  • We are using the local path for the database so that data will retain even if container get deleted
  • We are creating a new user testuser for our database. If you want to use same root user then you do not need to provide the user parameter ,only password parameter is required to set the password
version: '3.3'
services:
   db:
     image: mysql:5.7
     volumes:
       - /opt/test:/var/lib/mysql
     environment:
       MYSQL_ROOT_PASSWORD: root
       MYSQL_DATABASE: testdb1
       MYSQL_USER: testuser
       MYSQL_PASSWORD: root
     ports:
       - 3306:3306
phpmyadmin:
    depends_on:
      - db
    image: phpmyadmin/phpmyadmin
    ports:
      - '8081:80'
    environment:
      PMA_HOST: db
      MYSQL_ROOT_PASSWORD: root

Run the docker-compose

docker-compose -f docker-compose_mysql_phpMyAdmin.yml up -d

Logged on phpmyadmin and create some table to test if it persist or not

http://yourip:8081/

Now clean your container 

docker-compose -f docker-compose_mysql_phpMyAdmin.yml down

Rerun the container 

docker-compose -f docker-compose_mysql_phpMyAdmin.yml up -d

You should be able to see the table which you have created 

How to import .sql file in docker-compose file

This is required if you need to import the existing sql file so that every developer who runs the container can have all the database tables and some sample data created 

mysql-dump must be a directory. All the .sql’s in the directory will be imported.

version: '3.3'
services:
   db:
     image: mysql:5.7
     volumes:
       - /opt/test:/var/lib/mysql
       - ./mysql-dump:/docker-entrypoint-initdb.d
     environment:
       MYSQL_ROOT_PASSWORD: root
       MYSQL_DATABASE: testdb1
       #MYSQL_USER: testuser
       MYSQL_PASSWORD: root
     ports:
       - 3306:3306
phpmyadmin:
    depends_on:
      - db
    image: phpmyadmin/phpmyadmin
    ports:
      - '8081:80'
    environment:
      PMA_HOST: db
      MYSQL_ROOT_PASSWORD: root

Congratulations, you have successfully installed the docker-compose and ran the tomcat application with mysql database using docker-compose.

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