What's wrong with latest tag?

[tigerinus]

Hello, fellow CasaOS App contributors and users!

Thanks for all your support to grow this AppStore.

You might have noticed that the image of each app in this AppStore does not use latest tag. Instead it uses a specific tag which most likely looks like a version string.

So why not use latest tag all the time?

There are 2 problems from our perspective:

1. In the past we did pull the entire image down to compare the hash with local image, but that makes Check and update super time consuming for users without great internet access speed.

   Yes, Docker Hub does provide API to pull the digest without pulling the entire image, e.g. "sha256:5b54f3fc806150bd122f6e7feb992e307464c12c41e8eb99a72e8ad6d9677e7f", so we can compare it instead of the tag.

   However it is not a standard for many other container registries. There are images hosted on somewhere else.

2. In addition to that, when there is a major version change in some app (0.1.2 -> 2.0.0), say completely redesigned the setting schema for example. Most likely they will continue with latest tag for the new version 2.0.0.

   However manifest file from AppStore most likely stay as is, and thus become incompatible with the major change, and sometime cause app to stop working or behave weirdly.

Because of these reasons, we are keeping the tags specific.

See What's Wrong With The Docker :latest Tag? for more information about this subject.