A part of the 60-day ReadList series – Simplifying Docker & Kubernetes, one post at a time!

1. What is Docker Compose?

Docker Compose is a tool for defining and running multi-container Docker applications.
Instead of running multiple docker run commands, you can define your application stack in a single YAML file.

Why Use Docker Compose?

Simplifies multi-container management
Provides a single command to start, stop, and rebuild services
Better organization of Docker infrastructure

Docker Compose File Structure (docker-compose.yml)

version: '3.8'
services:
  web:
    image: nginx:latest
    ports:
      - "80:80"
    volumes:
      - ./html:/usr/share/nginx/html
  db:
    image: mysql:8.0
    environment:
      MYSQL_ROOT_PASSWORD: example
    volumes:
      - db_data:/var/lib/mysql

volumes:
  db_data:

Explanation:

services: Defines different containers (e.g., web, db).
image: Image to use for each service.
ports: Mapping between host and container ports.
volumes: Persistent storage (explained below).
environment: Environment variables (useful for DB credentials, etc.).

2. Docker Volumes

Docker Volumes are used for persisting data generated or used by Docker containers.

Why Use Volumes?

Data is retained even if the container is deleted.
Can be shared between containers.
Improves performance compared to bind mounts.

Types of Volumes:

Type	Description	Example Usage
Anonymous Volumes	Temporary storage, removed when container is deleted.	`docker run -v /data nginx`
Named Volumes	Persistent storage, managed by Docker.	`docker volume create myvolume`
Bind Mounts	Directly mount host directories into containers.	`-v /host_path:/container_path`

Creating & Using Volumes in Docker Compose

Defining Volumes in docker-compose.yml

version: '3.8'
services:
  app:
    image: myapp
    volumes:
      - app_data:/app/data
volumes:
  app_data:

This will create a persistent volume named app_data managed by Docker.

Inspecting Volumes

docker volume ls

Removing a Volume

docker volume rm app_data

3. Docker Compose Commands

Task	Command
Start services	`docker-compose up`
Start in detached mode	`docker-compose up -d`
Stop services	`docker-compose down`
List running containers	`docker-compose ps`
View logs	`docker-compose logs`

4. Summary

Docker Compose makes managing multi-container apps easy and efficient.
Volumes ensure your data is persistent and accessible across containers.
Simplifies deployment by defining services in a single .yml file.

Stay tuned for upcoming posts about Kubernetes folks. Share your support through
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ReadList #4 - Docker Compose & Docker Volumes: