Why Docker Compose simplifies multi-container apps - See It in Action

Why Docker Compose simplifies multi-container apps

📖 Scenario: You want to run a simple web app that needs two parts: a web server and a database. Managing each part separately is hard and slow.Docker Compose helps you start both parts together with one command.

🎯 Goal: Build a Docker Compose setup that runs a web server and a database together easily.

📋 What You'll Learn

Create a docker-compose.yml file with two services: web and db

Set the web service to use the nginx:latest image

Set the db service to use the mysql:5.7 image with environment variables

Use Docker Compose commands to start and show running containers

💡 Why This Matters

🌍 Real World

Many apps need multiple parts like a web server and database. Docker Compose helps run them together easily.

💼 Career

DevOps engineers use Docker Compose to manage multi-container apps during development and testing.

1

Create the initial Docker Compose file

Create a file named docker-compose.yml with a version set to '3.8' and an empty services section.

Docker

# Create docker-compose.yml with version '3.8' and empty services
version: '3.8'
services:
  # Your code here

Need a hint?

The version key defines the Compose file format version. The services section will hold your app parts.

2

Add the web and db services

Add two services under services: web using image nginx:latest and db using image mysql:5.7.

Docker

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

Need a hint?

Indent the services properly under services. Use image to specify the container image.

3

Configure environment variables for the db service

Under the db service, add an environment section with MYSQL_ROOT_PASSWORD set to 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 are set as key-value pairs under environment.

4

Start the app and check running containers

Run docker-compose up -d to start the services in the background, then run docker-compose ps to list running containers.

Docker

# Run docker-compose up -d
# Run docker-compose ps
# Your code here

Need a hint?

Use docker-compose up -d to start containers quietly in the background. Use docker-compose ps to see their status.