Reverse Lookup for Identity to Pod/Deployment Mapping

[zip-chanko]

We're using server authorizations with client identities in Linkerd to manage which workloads can communicate with each other. However, there's no easy way to do a reverse lookup to see which pod or deployment an identity belongs to. It would be super helpful for a couple of reasons:

• ACL Review: Scraping all the server authorizations across the cluster to see who can talk to whom and make sure everything's locked down as intended.
• Identity Cleanup: When an app gets decommissioned, its identity might still be hanging around in the ACL, and without knowing where it was used, it could sit there as a stale entry. Cleaning these up regularly, especially for audits, would be great.

A reverse lookup command (like linkerd identity <pod>, but the other way around) could make this process a lot easier.

There is a workaround with kubectl get pods -A -o yaml and grep, but it'd be nice to have a more straightforward approach.