This is all based on how the RunTime API worked already (pre-dates this launch by 2 years or so). We wanted to not change too many bits. Since function code ha

This is all based on how the RunTime API worked already (pre-dates this launch by 2 years or so). We wanted to not change too many bits. Since function code has no listening socket/port as it were you need something (like the bootstrap script in a custom RunTime) to pull the local interface for the runtime API. That runs on the underlying worker and communicates with the API for Lambda.