Edge Routing Nearest Lambda Function URL

[huntharo]

Overview

Function URLs would not have API Gateway to proxy requests to specific application versions. Specific application versions can have unique Function URLs though.

Using Lambda @ Edge to rewrite the origin URL would allow sending version-specific requests to a specific version of an app without having to proxy the request/response and without having to pay for that proxying lambda to site around waiting for the response.

Function URLs appear to remove up to 10 ms of latency compared to API Gateway (should document that in another ticket) and have lower/no cost compared to API Gateway, so they will be desirable to some MicroApps users.

Steps

• Download list of apps / versions on startup of edge to origin lambda
  • Include region-specific URLs for origins of that app/version
  • regions between apps/versions do not need to be consistent - app1/0.0.0 may be in us-east-1 and us-east-2, but app1/0.0.1 may only be in us-east-2
• On request to specific app / version, check in-memory table for function URL or nearest API Gateway URL for that app
• If in-memory table does not have that app or app / version combo, hit DynamoDB (eventually nearest-region replica) to see if it exists and has a URL
  • Save that URL in the in-memory table if it exists
• Change the origin URL to the specific target URL