This is a simple API that serves cupcake data from a database. The goal is to:
- Demonstrate how to make two Docker containers work together.
- Use Docker Compose to make the process more manageable.
By design, Docker containers are isolated from each other. In order for two containers to "talk" to each other, they need to be on the same network. And because containers are isolated from the host, their data won't be persisted unless we mount a volume.
docker network create cupcakesdocker volume create pgdata
There's a Dockerfile for the Postgres database in the db directory. We need to build the image and run a container. We'll put the container on the cupcakes network and give it a network alias that the other container can use instead of an IP address. We'll also mount the the pgdata volume to the /var/lib/postgresql/data directory in the container (where Postgres stores its data).
docker build ./db -t cupcakes-dbdocker run -d --network cupcakes --network-alias postgres -v pgdata:/var/lib/postgresql/data cupcakes-db
There's a Dockerfile for the Node app in the root directory. We need to build the image and run a container. We'll put the container on the cupcakes network.
docker build . -t cupcakes-appdocker run -dp 3000:3000 --network cupcakes cupcakes-app
This works, but it's difficult to remember all these commands and flags! Using Docker Compose, we can configure all of our services in a single compose.yaml file and spin them up with a single command. And even better, Docker Compose automatically adds the services to the same network.
To build both images, we can run docker compose build. Then to spin everything up, we can run docker compose up. To tear everything down, we can run docker compose down.
docker compose builddocker compose updocker compose down