Registry is a service that stores, manages, and distributes images. Public services, such as Docker Hub (https://hub.docker.com) and Quay (https://quay.io), converge all kinds of pre-built images of popular tools, such as Ubuntu and Nginx, and custom images from other developers. The Alpine Linux we have used many times is actually pulled from Docker Hub (https://hub.docker.com/_/alpine). Absolutely, you can upload your tool onto such services and share with everyone as well.
If you need a private registry, but for some reason you don't want to subscribe to paid plans of registry service providers, you can always set up one on your own with registry (https://hub.docker.com/_/registry).
Before provisioning a container, ...
