Docker Env Setup & Debugging

My containerised application refuses to pick up its application config variables when I run it with Docker on my local machine. Inside the codebase I rely on dotenv, yet without a proper .env file the values never reach the app. I need practical guidance to:

• craft the initial .env file (names, sample values, and correct permissions),
• adjust the Dockerfile or docker-compose so that dotenv finds those variables every time I build and run, and
• confirm the container starts locally with all expected configuration present.

Once that baseline works, we will polish the image so it can be pushed to AWS ECR and launched on ECS without surprises—same environment variables, same behaviour.

Please be comfortable with Docker CLI, docker-compose, dotenv conventions, and the AWS ECR/ECS workflow. When we finish, I expect a running local container, the finished Dockerfile/compose files, the sample .env, and a concise set of commands I can reuse for the ECR push and ECS task definition.