What's the purpose of “docker build --pull”?

Question

When building a docker image you normally use docker build ..

But i\'ve found that you can specify --pull, so the whole command would look like

Answer 1

Docker allows passing the --pull flag to docker build, e.g. docker build . --pull -t myimage. This is the recommended way to ensure that the build always uses the latest container image despite the version available locally. However one additional point worth mentioning:

To ensure that your build is completely rebuilt, including checking the base image for updates, use the following options when building:

--no-cache - This will force rebuilding of layers already available.

The full command will therefore look like this:

docker build . --pull --no-cache --tag myimage:version

The same options are available for docker-compose:

docker-compose build --no-cache --pull