We are currently using a function called get_http_client_session in various isvcs as attempt to reuse the same connection pools when connecting to endpoints. For example, we have calls like:

get_http_client_session("mwapi")
get_http_client_session("restgateway")
etc..

Our current network model on Lift Wing relies on the following:

• http (plaintext) request to the endpoint, that ends up being redirected to the localhost Envoy proxy.
• the Envoy proxy (Istio) makes then a TLS connection (so using a separate TCP conn pool) to the endpoint (behind the scenes).

This rewrite is needed to allow the Envoy proxy to publish L7/HTTP metrics for our dashboards. We use the Istio Destination Rule config to tune the TCP/TLS connection pool, so we should be ok in simply using a context manager with a new aiohttp session every time in the Python isvc code.

This task should investigate pros/cons of the current approach, and refactor/simplify the code in case a simpler approach is better. With better I mean several things:

• More maintainable, since there will be no issues related to session re-use by mistake (say if we use the same parameter in get_http_client_session() for two different endpoints).
• Easier to read and modify.
• Easier to debug/reason-about when a connection fails for some reason (since with a simple context manager + new session every time it will be less likely to be a problem).