Bug: renovate is unable to track image updates (unsupported/unversioned value) about image-tools

[Artyop]

Since a unique repository is used to managed multiple different images, using the identifier (sha1) of a commit will force the update of every image every time one (or more) images need a tag bump.
That is why the first solution (used before renovate) was actually using the tree hash of the image's directory(sha256).

Renovate doesn't know how to sort SHA as stated in this github discussion renovatebot/renovate#23459
More informations on the way renovate reads SHA tags were found here : renovatebot/renovate#25849

Multiple approach have been tested so far :
Using latest tag in order to bypass the need for renovate to sort any SHA tag.
Unfortunately, and contrary to what discussion 23459 states, Renovate doesn't seem to be able to read latest tags (tested locally, message was the same as the SHAs error message but with latest).

Setup a proper semver mechanic would take a long time and add more maintenance to ensure the proper bumping of versions.

Fetching the last commit per directory using git log, and extract its timestamp could be the right way to go :

• The git log command, when given a specific directory in parameter, retrieve the last commit were changes were made in said directory.
  This means that we can ensure different image versions same as used to be with git-tree.
• Renovate easily sort versions from left to right, which means using a timestamp as a tag value would allow renovate to retrieve the latest version deployed with ease. (Tested locally and it worked fine)
• Few code would be needed to perform this action and would need the same amount of maintenance as the old solution.

[Artyop]

Had issue with auto-update of runtime and builder images in cilium/cilium, finally managed to fix those by changing the already existing workflows to update those in this PR : cilium/cilium#34372

[auriaave]

I think this issue can be closed? Thank you for the fix!