Building an Image

Build from the current folder

The final argument is the build context (usually .). Docker sends that context to the daemon and runs the Dockerfile.

docker build -t my-hello:1.0 .

Run your image

Use the tag you chose. Publish port 8000 so you can hit the app from the host.

docker run --rm -d --name my-hello -p 8000:8000 my-hello:1.0
curl http://localhost:8000

Rebuild after edits

Change app.py, rebuild with the same tag, then recreate the container. Old containers keep running the old image until you replace them.

docker stop my-hello
docker build -t my-hello:1.0 .
docker run --rm -d --name my-hello -p 8000:8000 my-hello:1.0

Watch layer caching

Docker reuses unchanged layers. Put rarely changing steps (install dependencies) before frequently changing ones (copy source) to speed rebuilds as projects grow.