05 Configure with environment variables

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Goal

Get a postgres:17 container called db running in the background, with the superuser password secret.

Images are configured at run time with environment variables, passed with -e NAME=value. The same image becomes a dev database or a production one depending on what you pass.

When a container exits unexpectedly, docker logs <name> is the first thing to read. A container's logs are whatever its main process printed — and they survive after it stops.

Try it

Run postgres without configuring it first. See it exit, read the logs, and fix it.

Real passwords don't belong on the command line — they end up in your shell history. Use an env file or your platform's secret store.

Go to the terminal

Hint

It exits straight away without a password — docker logs db says why. Remove it, then docker run -d --name db -e POSTGRES_PASSWORD=secret postgres:17.

Show a solution

docker run -d --name db postgres:17
docker ps -a
docker logs db
docker rm db
docker run -d --name db -e POSTGRES_PASSWORD=secret postgres:17

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