Multi-Container Apps with Docker Compose
Use Docker Compose to define and run multi-service applications (app, database, cache) together with a single declarative file.
Multi-Container Apps with Docker Compose is a free AI Powered SaaS: Stripe + Auth + Billing + Deploy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the AI Powered SaaS: Stripe + Auth + Billing + Deploy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Why Docker Compose?
Real apps rarely run in one container. You often need a web app, a database, and a cache. Docker Compose lets you define all of them in one YAML file and start them with a single command.
The compose.yaml File
Compose reads a file named compose.yaml (or docker-compose.yml). Each entry under services describes one container.
services:
web:
build: .
ports:
- "3000:3000"
db:
image: postgres:16Defining a Service
A service can be built from a local Dockerfile or pulled as an existing image. You also set ports, environment variables, and dependencies here.
Environment Variables
Pass configuration with environment or load from an .env file. Never hardcode secrets directly in the YAML committed to git.
services:
db:
image: postgres:16
environment:
POSTGRES_PASSWORD: ${DB_PASSWORD}Service Networking
Compose puts all services on a shared network. A service reaches another by its service name as the hostname. The web app connects to the database at db:5432.
Persisting Data with Volumes
Containers are ephemeral. Use a named volume so database data survives restarts and rebuilds.
services:
db:
image: postgres:16
volumes:
- dbdata:/var/lib/postgresql/data
volumes:
dbdata:Startup Order with depends_on
depends_on controls start order, but it does not wait for a service to be ready. Combine it with a healthcheck so the web app waits until the database accepts connections.
Bringing It Up and Down
Start everything in the background with up -d and stop with down. Add --build to rebuild images after code changes.
docker compose up -d --build
docker compose downViewing Logs
Aggregate logs from all services or follow one. This is essential for debugging how containers interact.
docker compose logs -f webScaling a Service
Run multiple copies of a stateless service to handle more load. Put a load balancer or reverse proxy in front to distribute traffic.
docker compose up -d --scale web=3Compose for Dev vs Production
Use a base compose.yaml plus an override file for each environment. Development might mount source code for hot reload; production uses prebuilt images and stricter restart policies.
Quick Check
Check your Docker Compose knowledge.
Recap
You learned to orchestrate multi-container apps with Docker Compose:
- Define services in
compose.yaml - Connect them via service-name networking
- Persist data with volumes and control order with depends_on/healthcheck
- Use
up,down, logs, and scaling
Compose makes local and production multi-service setups reproducible.
Frequently asked questions
Is the “Multi-Container Apps with Docker Compose” lesson free?
Yes — the full text of “Multi-Container Apps with Docker Compose” is free to read here on the web, and the AI Powered SaaS: Stripe + Auth + Billing + Deploy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the AI Powered SaaS: Stripe + Auth + Billing + Deploy course, upgrade to CoddyKit PRO.
What will I learn in “Multi-Container Apps with Docker Compose”?
Use Docker Compose to define and run multi-service applications (app, database, cache) together with a single declarative file. You practise AI Powered SaaS: Stripe + Auth + Billing + Deploy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start AI Powered SaaS: Stripe + Auth + Billing + Deploy?
No prior experience is required. AI Powered SaaS: Stripe + Auth + Billing + Deploy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Multi-Container Apps with Docker Compose” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this AI Powered SaaS: Stripe + Auth + Billing + Deploy lesson?
Yes. Every AI Powered SaaS: Stripe + Auth + Billing + Deploy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Dockerizing Your Application
- Introduction to Cloud Providers
- Deploying to a Cloud VM
- Multi-Container Apps with Docker Compose