I’m in a situation where I need to use a specific patch version of Ubuntu (20.04.03) but the lastest official ubuntu:20.04 image is on 20.04.05. I’ve heard that one can use the older image if you can get the digest for it but is there a way to search for the digest of older images on dockerhub?
In general, no. There is no history like that built into Docker Hub. A tag is just a pointer to a specific image that you can change any time. On the other hand, the version tag is often just an alias of a more specific tag. For example v2.3 could be an alias of v2.3.2. In case of Ubuntu, you can search for the codename and a hyphen on Docker Hub like this:
It will be followed by dates. If you know the date of a release, you can use a specific release.