Comment by sebazzz
6 years ago
Companies might base their image based on another image in the docker registry. That image might be good now, might be good in two years, but what if I want to pull a, say .NET Core 1.1 docker image in four years?
Now, .NET Core 1.1 might not be the best example, but I'm sure you can think of some example.
If you anticipate needing that image around in 4 years for a critical business case, you can either pull it once every 6 months from here on out, download the image and store it somewhere yourself, or make a fully reproducible Dockerfile for it so the image can be re-created later if it disappears from the registry.