Add support for traces in Cloud Foundry receiver

[jriguera]

Component(s)

receiver/cloudfoundry

Is your feature request related to a problem? Please describe.

Applications running in Cloud Foundry can sent traces directly to an OTLP endpoint, but the trace ID for the root span is generated (if not present) in the Gorouters (the reverse proxy on top of the applications HTTP routes). When an user query Spans or Traces in the backed (Grafana Tempo in our case) they get a message <root span not yet received> because there is no way to ingest those in the backend as root spans.

Following the PR #33044 we would like to continue adding support for traces in Cloud Foundry.

Describe the solution you'd like

Implement parsing of CF Gorouter access logs (source_id RTR) to convert them to Spans if possible.

The Gorouter access log is text based format separated by spaces, optionally extra headers are present with the format key:"value"

www.example.com - [2024-05-21T15:40:13.892179798Z] "GET /articles/ssdfws HTTP/1.1" 200 0 110563 "-" "python-requests/2.26.0" "20.191.2.244:52238" "10.88.195.81:61222" x_forwarded_for:"18.21.57.150, 10.28.45.29, 35.16.25.46, 20.191.2.244" x_forwarded_proto:"https" vcap_request_id:"766afb19-1779-4bb9-65d4-f01306f9f912" response_time:0.191835 gorouter_time:0.000139 app_id:"e3267823-0938-43ce-85ff-003e3e3a5a23" app_index:"4" instance_id:"918dd283-a0ed-48be-7f0c-253b" x_cf_routererror:"-" x_forwarded_host:"www.example.com" x_b3_traceid:"766afb1917794bb965d4f01306f9f912" x_b3_spanid:"65d4f01306f9f912" x_b3_parentspanid:"-" b3:"766afb1917794bb965d4f01306f9f912-65d4f01306f9f912" traceparent:"00-766afb1917794bb965d4f01306f9f912-65d4f01306f9f912-01" tracestate:"gorouter=65d4f01306f9f912"

The idea is parse each logline, look for W3C standard tracing headers and if not present try Zipkin headers and convert all information to a Span.

Moreover, logs can get the traceID and SpanID fiels filled with the same implementation.

Describe alternatives you've considered

Currently there is no alternative to get CF root spans in OTEL

Additional context

Enabling tracing in CF: https://docs.cloudfoundry.org/adminguide/w3c_tracing.html

CF loggregator architecture: https://docs.cloudfoundry.org/loggregator/architecture.html

[github-actions]

Pinging code owners:

• receiver/cloudfoundry: @crobert-1

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[github-actions]

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Pinging code owners:

• receiver/cloudfoundry: @crobert-1

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[jriguera]

Still working on it