A Docker image tag gives an image a readable reference for build, push, and run commands. Build with `docker build -t video-streaming --file Dockerfile .`; the final period selects the current directory. Without a specified version, the tag is `latest`. Use `docker image list` to check the repository, tag, and image ID. section 3.8.2
To publish the image, give it a tag containing your registry URL: `docker tag <existing-image> <registry-url>/<image-name>:<version>`. This adds a reference to the existing image; it does not build another image. Check `docker image list`: both tags should show the same image ID. Then push the registry-qualified tag with `docker push <registry-url>/<image-name>:<version>`. section 3.9.2
Tag and publish a version
`docker tag video-streaming bmdk1.azurecr.io/video-streaming:1` followed by `docker push bmdk1.azurecr.io/video-streaming:1` publishes version `1` to the example registry. Substitute your own registry URL, and use the intended version when referencing the image later. section 3.9.2 section 3.9.3
Multiple tags can point to one image ID. When cleaning up locally, `docker rmi <your-image-id> --force` removes an image even when multiple tags reference it. A registry-qualified tag can also be passed to `docker run` to boot the published image. section 3.9.3
