Option to ignore specific keys

[timstoop]

Currently, there's an option to ignore entire resources, but I believe it's not possible to ignore specific keys instead. I'd love to be able to ignore things like .metadata.labels.helm.sh/chart and the like, as those are usually the most common and least interesting. Having the option to ignore a preset list of those key by default would make life a lot easier.

[gfdsa]

Helmfile user here. We had this this idea of tracking the helmfile runs using a label injected using kustomize into every freshly deployed resource. But being an updated value it triggers helmfile every time for every release event if there was no meaningful update. Helmfile bases its decision on helm-diff, so a way to ignore a label change would allow us to do exactly what we want.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[yxxhero]

#475

[gfdsa]

#475 is not exactly what I meant unfortunately.

Since --suppress-output-line-regex applied only to the output of an diff, the behavior of --detailed-exit-code is not touch. If there are differences which are suppressed, the exit code remains still 2.

What I need is to change the logic and not to report the changes at all if the only changed labels should be excluded.

[TheMeier]

Also if the resulting diff is empty it is quite confusing that a header is printed like

foo, foo-configmap, ConfigMap (v1) has changed:

followed by nothing

[TheMeier]

Related #768