docker-compose.yml structure - Mini Project: Build & Apply

Understanding docker-compose.yml Structure

📖 Scenario: You are setting up a simple web application using Docker Compose. This app has a web server and a database. You will create a docker-compose.yml file step-by-step to define these services.

🎯 Goal: Build a docker-compose.yml file that defines two services: web and db. The web service uses the nginx:latest image and the db service uses the mysql:5.7 image.

📋 What You'll Learn

Create a version key with value '3.8' in the YAML file

Define a services section with two services: web and db

Set the image for web to nginx:latest

Set the image for db to mysql:5.7

Add environment variables MYSQL_ROOT_PASSWORD: example to the db service

💡 Why This Matters

🌍 Real World

Docker Compose is used to run multi-container Docker applications easily on your local machine or servers.

💼 Career

Understanding <code>docker-compose.yml</code> files is essential for DevOps roles to manage containerized applications efficiently.

1

Create the YAML version key

Create a docker-compose.yml file and add the version key with the value '3.8' at the top.

Docker

# Add the version key with value '3.8'
# Your code here

Need a hint?

The version key tells Docker Compose which file format version you are using.

2

Add the services section with web and db

Add a services section below version. Inside services, define two services: web and db.

Docker

version: '3.8'
# Add services section with web and db
# Your code here

Need a hint?

The services section groups all your app's containers.

3

Set images for web and db services

Under the web service, add image: nginx:latest. Under the db service, add image: mysql:5.7.

Docker

version: '3.8'
services:
  web:
    # Add image nginx:latest
  db:
    # Add image mysql:5.7
# Your code here

Need a hint?

The image key tells Docker which container image to use for each service.

4

Add environment variable to db service

Add an environment section under the db service with MYSQL_ROOT_PASSWORD: example.

Docker

version: '3.8'
services:
  web:
    image: nginx:latest
  db:
    image: mysql:5.7
    # Add environment variable MYSQL_ROOT_PASSWORD: example
# Your code here

Need a hint?

Environment variables configure the container. Here, it sets the MySQL root password.