Bug: WebSocket upgrade requests fail on HTTP/2 listeners

[benmurden]

Summary
We have an App Mesh setup with a Virtual Gateway. When using HTTP/2 listeners on the VGW, WebSocket upgrade requests return 503 UC from the VGW.

Steps to Reproduce

• Setup a simple WebSocket service with Envoy sidecar and HTTP/2 listeners.
• Add Virtual Gateway service with HTTP/2 listeners.
• Attempt WebSocket upgrade.

Are you currently working around this issue?
Using HTTP/1.1 listeners allows WebSocket upgrades to work correctly.

Additional context
There is a configuration option in Envoy to allow connection upgrades tunneled through HTTP/2.
https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/http/upgrades#websocket-over-http-2-or-http-3-hops

Attachments
Log sample for WebSocket upgrade attempt.

HTTP/1.1" 503 UC 0 95 1003