Docker-compose is a command line tool to define and configure multi-container docker applications. In other words we can say docker compose is used to link multiple containers and deploy application from a single command. Let’s assume we want to deploy WordPress site inside a container, so to deploy this i would be requiring one Web Server container (Apache/ nginx) and one database container (mysql / mariadb).
With Docker Compose we can easily include multiple containers inside our docker-compose file and can also define all other configuration required for my application. Docker-compose tool can be used in development, testing and staging environment, apart from these it can be easily used in CI (Continues Integration) workflow
In this article we will discuss how to install Docker Compose on existing Docker host and then we will learn how to deploy containers from docker-compose command. In our previous article we have already discuss the following topics.
I am assuming here that we have existing docker host up and running. Now let’s jump into the installation steps of docker compose tool.
Installation steps of Docker Compose
Login to your docker host and run the beneath commands one after the another
[root@docker-host ~]# yum install epel-release -y [root@docker-host ~]# yum install python-pip -y [root@docker-host ~]# pip install docker-compose
Note: pip version 6.0 or higher is recommended for docker-compose to work smoothly. In case pip version is below 6.0 then run the below command to upgrade it
[root@docker-host ~]# pip install --upgrade pip
Verify the Docker version using below command
[root@docker-host ~]# docker-compose --version docker-compose version 1.15.0, build e12f3b9 [root@docker-host ~]#
Deploy Containers with Docker Compose tool
To deploy docker containers with docker-compose command , first create a directory under that directory create a compose file with name ‘docker-compose.yml‘ or ‘docker-compose.yaml‘. In the compose file we will define the services for our applications and container images.
Before start creating compose file, let’s first pull WordPress and MySQL container images
[root@docker-host ~]# docker pull wordpress [root@docker-host ~]# docker pull mysql [root@docker-host ~]# docker image ls REPOSITORY TAG IMAGE ID CREATED SIZE mysql latest c73c7527c03a 2 days ago 412MB wordpress latest f28808014819 7 days ago 406MB
Create a directory with name “wordpress-site”
[root@docker-host ~]# mkdir wordpress-site [root@docker-host ~]# cd wordpress-site/ [root@docker-host wordpress-site]#
Create docker-compose.yml file with the following content
version: '3.0' services: webserver: image: wordpress container_name: wp_web ports: - 8080:80 links: - dbserver:mysql environment: WORDPRESS_DB_PASSWORD: 6zcznAEjLWp79P dbserver: image: mysql:latest container_name: wp_db environment: MYSQL_ROOT_PASSWORD: 6zcznAEjLWp79P
In the above compose file we have define two services with the name “webserver” and “dbserver”, for these services I have also specified container image . Apart from this I have specify environments by mentioning the mysql root password and wordpress db password.
Let’s deploy our application i.e WordPress site by running the below command,
[root@docker-host wordpress-site]# docker-compose up
Note: Run ‘docker-compose up’ command from the directory where docker-compose file exists.
Above Command will deploy two containers with name “wp_web” and “wp_db”. Try access your WordPress site using URL :
http://{docker-host-ip}:8080
Complete the screen instructions to finish WordPress Installation. This confirms that we have successfully deployed WordPress site inside the containers using docker-compose tool.
Let’s have a look on options of ‘docker-compose’ command
List the Containers which are deployed for our application
[root@docker-host wordpress-site]# docker-compose ps Name Command State Ports ---------------------------------------------------------------------- wp_db docker-entrypoint.sh mysqld Up 3306/tcp wp_web docker-entrypoint.sh apach ... Up 0.0.0.0:8080->80/tcp [root@docker-host wordpress-site]#
Stop and start the Containers & Its Services
Either press Ctrl+C on the command or run below command
[root@docker-host wordpress-site]# docker-compose stop Stopping wp_web ... done Stopping wp_db ... done [root@docker-host wordpress-site]#
Run ‘docker-compose start’ to start containers and its services
[root@docker-host wordpress-site]# docker-compose start Starting dbserver ... done Starting webserver ... done [root@docker-host wordpress-site]#
View the Containers Logs
Run ‘docker-compose logs’ command to view logs of containers and to view the logs of a specific container use the command ‘docker-compose logs {service-name}’
[root@docker-host wordpress-site]# docker-compose logs [root@docker-host wordpress-site]# docker-compose logs dbserver
Stop & Remove Containers along with its network
With help of ‘docker-compose down’ command we can stop and remove containers from a single command
[root@docker-host wordpress-site]# docker-compose down Stopping wp_web ... done Stopping wp_db ... done Removing wp_web ... done Removing wp_db ... done Removing network wordpresssite_default [root@docker-host wordpress-site]#
That’s all from this tutorial, For more options please refer “docker-compose –help“
