Phase 5Intermediate6 of 11 in Docker

Docker Compose

Stop typing 15-flag docker run commands by hand — describe your whole multi-container app in one file.

Real applications are rarely one container. A Spring Boot app, a Postgres database, a Redis cache, maybe a message broker — Compose lets you define, network, and run all of them together with one command.

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3 topics ~40 min 8 code blocks & diagrams

Start with the first topic

5.1

Why Compose & Your First compose.yaml

Compose turns a page of docker run commands you'd have to remember and retype into one readable, version-controlled YAML file that anyone on your team can run identically.

14 min 2 code practice

5.2

Startup Order, Dependencies & Healthchecks

depends_on alone only controls START ORDER, not READINESS — a subtle distinction that causes a huge number of 'my app crashes on startup because the database wasn't ready yet' bugs.

13 min 1 diagram 1 code practice

5.3

Environment Variables, .env & Multiple Compose Files

Keeping secrets and per-environment differences OUT of your committed compose.yaml, and layering multiple Compose files for dev vs production variations of the same base stack.

13 min 4 code practice

Command Palette

Why Compose & Your First compose.yaml

Startup Order, Dependencies & Healthchecks

Environment Variables, .env & Multiple Compose Files