Feature servers

Feast users can choose to retrieve features from a feature server, as opposed to through the Python SDK.

Python feature serverhttps://github.com/feast-dev/feast/blob/v0.22-branch/docs/reference/feature-servers/go-feature-server.mdhttps://github.com/feast-dev/feast/blob/v0.22-branch/docs/reference/feature-servers/alpha-aws-lambda-feature-server.md