5 Sharing images with Docker Hub and other registries
You’ve spent the last few chapters getting a good understanding of the build and run parts of the Docker workflow—now it’s time for share. Sharing is all about taking the images you’ve built on your local machine and making them available for other people to use. I think this is the most important part of the Docker equation. Packaging your software along with all its dependencies means anyone can use it easily, on any machine—there are no gaps between environments, so there are no more days wasted setting up software or tracking down bugs that are actually deployment problems.
5.1 Working with registries, repositories, and image tags
Software distribution is built into the Docker platform. You’ve already seen that you can run a container from an image, and if you don’t have that image locally, Docker will download it. The server that stores images centrally is called a Docker registry. Docker Hub is the most popular image registry, hosting millions of images, which are downloaded billions of times every month. It’s also the default registry for the Docker Engine, which means it’s the first place Docker looks for images that aren’t available locally.