Include own headers in envoy logs.

[cw-sakamoto]

#1511 can export the envoy log in json format, but the corresponding items are hard-coated at https://github.com/projectcontour/contour/blob/master/internal/envoy/accesslog.go#L26-L49.

Isn't it possible to make JSONFields itself variable by writing config as shown below?

data:
  contour.yaml: |
    accesslog-format: json
    json-fields:
      "@timestamp":  "%START_TIME%",
      "ts":  "%START_TIME%",
      "authority":  "%REQ(:AUTHORITY)%",
      "bytes_received":  "%BYTES_RECEIVED%",
      "bytes_sent":   "%BYTES_SENT%",
      "downstream_local_address":  "%DOWNSTREAM_LOCAL_ADDRESS%",
      "downstream_remote_address": "%DOWNSTREAM_REMOTE_ADDRESS%",
      "duration":  "%DURATION%",
      "method":    "%REQ(:METHOD)%",
      "path":   "%REQ(X-ENVOY-ORIGINAL-PATH?:PATH)%",
      "protocol":  "%PROTOCOL%",
      "request_id":  "%REQ(X-REQUEST-ID)%",
      "requested_server_name":  "%REQUESTED_SERVER_NAME%",
      "response_code":   "%RESPONSE_CODE%",
      "response_flags":   "%RESPONSE_FLAGS%",
      "uber_trace_id":   "%REQ(UBER-TRACE-ID)%",
      "upstream_cluster":  "%UPSTREAM_CLUSTER%",
      "upstream_host": "%UPSTREAM_HOST%",
      "upstream_local_address":  "%UPSTREAM_LOCAL_ADDRESS%",
      "upstream_service_time":   "%RESP(X-ENVOY-UPSTREAM-SERVICE-TIME)%",
      "user_agent":  "%REQ(USER-AGENT)%",
      "x_forwarded_for":  "%REQ(X-FORWARDED-FOR)%",

[davecheney]

Isn't it possible to make JSONFields itself variable by writing config as shown below?

It is not possible, but if you can tell us the items you'd like to add to this map (or send a PR yourself), we're happy to add them.

https://github.com/projectcontour/contour/blob/master/internal/envoy/accesslog.go#L26

[cw-sakamoto]

@davecheney
Thank you for the immediate reply!
x-trace-id is used internally. We confirmed that it can be obtained by adding as follows.

diff --git a/internal/envoy/accesslog.go b/internal/envoy/accesslog.go
index fddaeef..dd4a98f 100644
--- a/internal/envoy/accesslog.go
+++ b/internal/envoy/accesslog.go
@@ -46,6 +46,7 @@ var JSONFields = map[string]string{
        "upstream_service_time":     "%RESP(X-ENVOY-UPSTREAM-SERVICE-TIME)%",
        "user_agent":                "%REQ(USER-AGENT)%",
        "x_forwarded_for":           "%REQ(X-FORWARDED-FOR)%",
+       "x_trace_id":                "%REQ(X-TRACE-ID)%",
 }