### What?
I added a small change to the `with-docker-compose` example to show how to make the provided `.env` file usable.
### Why?
I struggled to understand why I could not get environment variables to work as intended and thought this small change might help someone else new to docker in the future.
### How?
Added a few comments to the `docker-compose.dev.yml` file, along with showing how to utilize a `.env` file with docker-compose
Co-authored-by: JJ Kasper <22380829+ijjk@users.noreply.github.com>
`with-docker-compose` contains everything needed to get Next.js up and running with Docker Compose.
This example aims to provide an easy-to-use, Next.js app development and production environment, **all without Node.js being installed** on the host machine. This ensures a consistent development environment across Windows, MacOS, and Linux teams.
I was inspired to create this, because the existing [with-docker](https://github.com/vercel/next.js/tree/canary/examples/with-docker) example only uses Docker to build the final production artifacts, not provide a development environment. Docker Compose easily syncs changes with containers for Hot Reloading, parallel builds, and networking, making it a powerful and consistent development tool.
Developers can **easily extend this example** by modifying the YAML files to include Nginx, Postgres, and other Docker images.
This example takes advantage of Docker multistage builds combined with the Next 12.1 [Output Standalone](https://nextjs.org/docs/advanced-features/output-file-tracing#automatically-copying-traced-files-experimental) feature, to create up to **80% smaller apps** (Approximately 110 MB compared to 1 GB with create-next-app). I also included an example without multistage builds, for developers who don't want to get into the weeds.
I have been tweaking this Docker Compose setup over 3 years of real world use, but please let me know if anything can be improved.
