UNIX domain socket paths are limited to 104-108 characters, depending on
the OS. This limit was quite easy to exceed when testing the feature on
Kubernetes, due to how proxy IDs encode the Pod ID eg:
metrics-collector-59467bcb9b-fkkzl-hcp-metrics-collector-sidecar-proxy
To ensure we stay under that character limit this commit makes a
couple changes:
- Use a b64 encoded SHA1 hash of the namespace + proxy ID to create a
short and deterministic socket file name.
- Add validation to proxy registrations and proxy-defaults to enforce a
limit on the socket directory length.
7c3e9cd862