envoy: improper 408 http status code

Envoy is returning 408 on lots of timeout cases. However, the 408 status code implies that the client did not produce a request within the time that the server was prepared to wait.

However, even the client does deliver the full request to envoy, envoy still returns status 408.

Example: when the backend of port 9080 is httpbin on 8080 docker run -p 8080:80 kennethreitz/httpbin envoy.yaml

curl -v --http2-prior-knowledge localhost:9080/delay/100
curl -v localhost:9080/delay/100

lambdai@lambdai:~$ curl -v localhost:9080/delay/80
*   Trying 127.0.0.1:9080...
* Connected to localhost (127.0.0.1) port 9080 (#0)
> GET /delay/80 HTTP/1.1
> Host: localhost:9080
> User-Agent: curl/7.80.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 408 Request Timeout
< content-length: 36
< content-type: text/plain
< date: Thu, 27 Jan 2022 22:39:43 GMT
< server: envoy