Request/Response body size metric per operation name

[grzn]

The metric 'apollo_router_http_request_duration_seconds' is great, exposing the duration for each Gql operation.
It would even better to have a metric for the request/response body sizes per opeation.

From what I gather this is not doable with a custom router metric (does not have the operation name selector/attribute) and not with a super graph selector/attribute (does not have the request/body size)

[bnjjj]

@grzn It's actually already possible using custom router metric but not really obvious neither well documented. To get the operation name you can have it using response_context selector and use the operation_name entry. That would result in something like this:

telemetry:
  instrumentation:
    instruments:
      router:
        http.server.request.body.size:
          attributes:
            graphql.operation.name:
              response_context: operation_name
        http.server.response.body.size:
          attributes:
            graphql.operation.name:
              response_context: operation_name

[grzn]

@bnjjj thanks, it works well for request body size, but not for response body size; after adding this, the metrics lo longer shows on he metrics response.

$ curl http://localhost:9091/metrics | grep http_server_res
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 69332  100 69332    0     0  53.4M      0 --:--:-- --:--:-- --:--:-- 66.1M

[bnjjj]

Thanks @grzn I'll try to reproduce. Could you tell me which version of the router are you using ?

[bnjjj]

I was able to reproduce @grzn. It's not related to the configuration but the implementation of the response body size metric itself. It's based on the value of content-length header but that header is not populated. I need to dig more in order to fix that issue I'll create a follow up issue and close this one.

[bnjjj]

#5319

[grzn]

cool, thanks @bnjjj