When you install this image, you pull the official CentOS build FROM DockerHub. Their image contains various Open Source licensed packages and their DockerHub home page ( https://hub.docker.com/_/centos ) provides licensing information. You can list the packages installed in the image by running 'rpm --query --all', and you can download the source code for the packages CentOS and DockerHub provide via the 'yumdownloader' command line tool.