endpoint sequences: Server-Timing header only reports last requests/proxies

[johakoch]

With endpoint sequences, server_timing_header = true only reports the "last" requests/proxies, not the dependencies.

server {
  hosts = ["*:8080"]

  endpoint "/**" {
    request "r" {
      url = "/req"
      backend = "be"
    }
    proxy { # has dependency "r"
      backend = "be"
      add_request_headers = {
        st = backend_responses.r.status
      }
    }
  }
}

definitions {
  backend "be" {
    origin = "http://localhost:8081"
  }
}

settings {
  server_timing_header = true
}

server {
  hosts = ["*:8081"]
  endpoint "/**" {
    response {
      status = 204
    }
  }
}

$ curl -si http://localhost:8080/foo
HTTP/1.1 204 No Content
...
Server-Timing: be_total;dur=0.709, be_ttfb;dur=0.452

Log (upstream):

INFO[0026]                                               backend=be build=dev custom="map[]" method=GET request="map[headers:map[] host:localhost method:GET name:r origin:localhost:8081 path:/req port:8081 proto:http]" response="map[bytes:0 headers:map[] status:204]" status=204 timings="map[dns:0.146 tcp:0.255 total:15.075 ttfb:0.511]" type=couper_backend uid=cfcf8ibeg9sborh08h9g url="http://localhost:8081/req" version=0
INFO[0026]                                               backend=be build=dev custom="map[]" depends_on=r method=GET request="map[headers:map[accept:*/* user-agent:curl/7.67.0] host:localhost method:GET name:default origin:localhost:8081 path:/foo port:8081 proto:http]" response="map[bytes:0 headers:map[] status:204]" status=204 timings="map[total:0.709 ttfb:0.452]" type=couper_backend uid=cfcf8ibeg9sborh08h9g url="http://localhost:8081/foo" version=0

As there are two backend requests (proxy "default") and request "r"), there should also be timings for request "r".

[malud]

blocked by #675