Docker-Compose
Docker Compose is a tool for running multi-container applications on Docker defined using the Compose file format. A Compose file is used to define how one or more containers that make up your application are configured. Docker Compose file is written in YAML format. Once you have a Compose file, you can create and start your application with a single command: docker compose up.
What is YAML?
YAML is a human-readable data serialization language that is often used for writing configuration files. YAML stands for yet another markup language. YAML is a popular programming language because it is designed to be easy to read and understand. YAML files use a .yml or .yaml extension, and follow specific syntax rules.
Creating Your First Docker-Compose File
vi docker-compose.yml
Let’s take a close look at the various details of this file −
The database and web keyword are used to define two separate services. One will be running our mysql database and the other will be our nginx web server.
The image keyword is used to specify the image from dockerhub for our mysql and nginx containers
For the database, we are using the ports keyword to mention the ports that need to be exposed for mysql and nginx.
And then, we also specify the environment variables for mysql which are required to run mysql.
Now let’s run our Docker Compose file using the following command −
docker-compose up -d
This command will take the docker-compose.yml file in your local directory and start building the containers. Once executed, all the images will start downloading and the containers will start automatically.
And when you do a docker ps, you can see that the containers are indeed up and running.
