Have an extractVersion like config for changelog version matching only

[viceice]

What would you like Renovate to be able to do?

I would like to have a feature like the extractVersion but that should only used for changelog retrieval.
With that way we can extract the version from eg 1.2.3-alpine to 1.2.3 to match against versions in changelogs, so renovate would be able to fetch the corresponding changes for an update like node:12.8.1-alpine to node:12.10.0-alpine.

Did you already have any implementation ideas?
not yet

Are there any workarounds or alternative ideas you've tried to avoid needing this feature?

not known to me.

Is this a feature you'd be interested in implementing yourself?

sure

[viceice]

example:

https://github.com/GoogleContainerTools/kaniko

They have a chgangelog and releases.

Maybe there is a bug and renovate should already handle this.

[viceice]

heres a sample pr: viceice-tests/renovate-changelog-kaniko#2