docker build

Relax. We'll talk through this in plain words — no textbook voice.

docker build reads your Dockerfile and builds a new image from it. This is the step where your own app gets turned into a reusable image.

dockerfile

# In the same directory as your Dockerfile
docker build -t my-custom-nginx:1.0 .

# Run the image as a container
docker run --name my-site -d -p 8080:80 my-custom-nginx:1.0

# Open http://localhost:8080 in your browser

-t my-custom-nginx:1.0 gives the image a name and tag. And at the very end, the . is the build context — it sends the Dockerfile and any needed files from the current folder into the Docker build process.

You should see

Once the build steps finish, you'll have a my-custom-nginx:1.0 image, and you'll be able to view the site in your browser.

Info

If your build context has a lot of unnecessary large files, the build can slow down. In a real project, .dockerignore should be added, and node_modules, logs, and cache files should be excluded.

Easy traps

Forget the trailing . and docker build won't know the context, so it'll throw an error. That little dot at the end of the command is tiny but important.