Docker Compose for Microservices with Scaling and Health Checks

A microservices architecture breaks a single application into many small, independent services that talk to each other over the network. This makes a system easier to scale and more resilient - each service can be run, updated, and recovered on its own - but it also raises new questions: how do services find each other, how do you know a service is truly ready to serve traffic (not just started), and how does the system recover when a container dies? Docker Compose answers all three for local and team-scale setups: a single docker-compose.yml describes the whole stack, Compose's built-in DNS lets services reach each other by name and load-balances across replicas, and health checks let the runtime tell "running" apart from "healthy."

Real-world stacks stay online because of three things: replicas, so the system survives a container dying; health checks, so the platform knows which replicas are ready; and restart policies, so failures heal themselves without waking anyone up. In this lab, you will work with a four-service stack — an Nginx API gateway, two backend services, and a RabbitMQ message queue — running inside a Docker IDE. You will bring the stack up and explore how it is wired, scale a backend to multiple replicas and watch Compose's DNS spread traffic across them, add health checks so Docker can report real readiness, apply a restart policy to the key services, and finally prove it all works by crashing a replica and watching the stack heal itself while still serving every request.

Objectives

Upon completion of this intermediate level lab, you will be able to:

• Understand how a multi-service docker-compose.yml connects an API gateway, two backend services, and a RabbitMQ message queue over a shared bridge network.
• Scale a backend service to multiple replicas with docker compose up --scale and verify DNS round-robin service discovery from inside the gateway container.
• Add a HEALTHCHECK directive to a service Dockerfile and configure a Compose-level healthcheck block on the RabbitMQ service.
• Apply restart: unless-stopped to critical services and demonstrate self-healing by killing a replica and observing automatic recovery.
• Inspect container health status, restart policies, and replica counts using docker compose ps, docker inspect, and Compose CLI commands.

Who is this lab for?

This lab is designed for:

• Developers and platform engineers who have written basic Dockerfiles and run single containers, now wanting to compose multi-service applications.
• DevOps practitioners moving from single-container thinking to multi-service stacks with service discovery, health probes, and restart-driven self-healing.