Docker Cheat Sheet Series (2/5): Building + Running Your App

Short scenarios. Copy/paste commands. Minimal notes.

Build an image from a Dockerfile

Goal: Turn your app into a Docker image.

docker build -t myapp:local .
docker images | head

Notes

• -t sets name:tag. Use a clear local tag like myapp:local.

Run with port mapping

Goal: Expose a container service to your machine.

docker run --rm -p 8080:8080 myapp:local

Notes

• Format is HOST:CONTAINER.
• If your app listens on 3000 inside the container: -p 8080:3000.

Run with environment variables

Goal: Configure the app without rebuilding the image.

docker run --rm \
  -e NODE_ENV=production \
  -e APP_PORT=8080 \
  -p 8080:8080 \
  myapp:local

Notes

• For many vars, prefer an env file:
  • docker run --rm --env-file .env -p 8080:8080 myapp:local

Use bind mounts for local development

Goal: Edit code on your machine, run inside container.

docker run --rm -it \
  -p 8080:8080 \
  -v "$PWD":/app \
  -w /app \
  myapp:local sh

Notes

• -v "$PWD":/app mounts current folder into the container.
• -w /app sets working directory.
• For better DX you often run a dev command inside (e.g., npm run dev).

Tag + push image to a registry

Goal: Publish your image for deployment/CI.

# tag for registry
docker tag myapp:local registry.example.com/myapp:1.0.0

# login + push
docker login registry.example.com
docker push registry.example.com/myapp:1.0.0

Notes

• Use immutable version tags (1.0.0) rather than only latest.