pkg/trace/api/otlp: support APM peer.service in OTLP

[songy23]

What does this PR do?

Implement OTLP support for APM peer.service in trace agent:

• Apply the peer.service defaults in cases where peer.service is missing.
  • Set the peer.service provenance tag _dd.peer.service.source={source_attribute}
• Stop the current behavior where the service={peer.service} if peer.service is non-empty
• Ensure span.kind is set correctly as the agent relies on this attribute to decide whether or not to calculate stats.

Motivation

To be compliant with the APM peer.service RFC and implementation (#16103).

Additional Notes

Possible Drawbacks / Trade-offs

This will be a breaking change to users who depend on overriding Service with span attribute peer.service.

Describe how to test/QA your changes

1. Send an OTLP span with attribute peer.service to Agent, then verify the DD span meta tag _dd.peer.service.source is set and DD Service isn't overridden with peer.service.
2. Send an OTLP span with attribute net.peer.name or any other default key to Agent, then verify the DD span meta tag
   peer.service and _dd.peer.service.source are set.
3. In any of the spans above, verify meta tag span.kind is set.

Reviewer's Checklist

• If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• Use the major_change label if your change either has a major impact on the code base, is impacting multiple teams or is changing important well-established internals of the Agent. This label will be use during QA to make sure each team pay extra attention to the changed behavior. For any customer facing change use a releasenote.
• A release note has been added or the changelog/no-changelog label has been applied.
• Changed code has automated tests for its functionality.
• Adequate QA/testing plan information is provided if the qa/skip-qa label is not applied.
• At least one team/.. label has been applied, indicating the team(s) that should QA this change.
• If applicable, docs team has been notified or an issue has been opened on the documentation repo.
• If applicable, the need-change/operator and need-change/helm labels have been applied.
• If applicable, the k8s/<min-version> label, indicating the lowest Kubernetes version compatible with this feature.
• If applicable, the config template has been updated.

[songy23]

@jdgumz Just noticed that the RFC proposed to set _dd.peer.service.source while #16103 sets peer.service. Could you confirm what is the expected behavior?

[pr-commenter]

Bloop Bleep... Dogbot Here

Regression Detector Results

Run ID: 3c2d7410-68d2-44dd-aa2c-429638ec4d87
Baseline: b9b2212
Comparison: 7d4dc82
Total datadog-agent CPUs: 7

Explanation

A regression test is an integrated performance test for datadog- agent in a repeatable rig, with varying configuration for datadog- agent. What follows is a statistical summary of a brief datadog- agent run for each configuration across SHAs given above. The goal of these tests are to determine quickly if datadog-agent performance is changed and to what degree by a pull request.

The table below, if present, lists those experiments that have experienced a statistically significant change in mean optimization goal performance between baseline and comparison SHAs with 90.00% confidence OR have been detected as newly erratic. Negative values mean that baseline is faster, positive comparison. Results that do not exhibit more than a ±5.00% change in their mean optimization goal are discarded. An experiment is erratic if its coefficient of variation is greater than 0.1. The abbreviated table will be omitted if no interesting change is observed.

No interesting changes in experiment optimization goals with confidence ≥ 90.00% and |Δ mean %| ≥ 5.00%.

Fine details of change detection per experiment.

experiment	goal	Δ mean	Δ mean %	confidence	baseline mean	baseline stdev	baseline stderr	baseline outlier %	baseline CoV	comparison mean	comparison stdev	comparison stderr	comparison outlier %	comparison CoV	erratic	declared erratic
otel_to_otel_logs	ingress throughput	14.1MiB/CPU-s	1.85	100.00%	761.7MiB/CPU-s	44.26MiB/CPU-s	584.71KiB/CPU-s	0.0	0.058102	775.8MiB/CPU-s	34.8MiB/CPU-s	459.78KiB/CPU-s	0.0	0.044857	False	False
uds_dogstatsd_to_api	ingress throughput	1.12KiB/CPU-s	1.47	92.65%	76.07KiB/CPU-s	34.28KiB/CPU-s	450.39B/CPU-s	0.0	0.450682	77.18KiB/CPU-s	34.42KiB/CPU-s	452.08B/CPU-s	0.0	0.445868	True	False
tcp_syslog_to_blackhole	ingress throughput	-3.55KiB/CPU-s	-0.05	44.17%	7.07MiB/CPU-s	306.33KiB/CPU-s	3.95KiB/CPU-s	0.0	0.042329	7.06MiB/CPU-s	357.17KiB/CPU-s	4.61KiB/CPU-s	0.0	0.049378	False	False
file_to_blackhole	egress throughput	-2.94B/CPU-s	-0.29	47.79%	1.0KiB/CPU-s	85.35B/CPU-s	2.93B/CPU-s	0.0	0.083124	1023.22B/CPU-s	102.59B/CPU-s	3.52B/CPU-s	0.0	0.100205	True	False
tcp_dd_logs_filter_exclude	ingress throughput	-1.62MiB/CPU-s	-1.02	100.00%	158.8MiB/CPU-s	8.71MiB/CPU-s	114.23KiB/CPU-s	0.0	0.054818	157.18MiB/CPU-s	11.33MiB/CPU-s	148.66KiB/CPU-s	0.0	0.072073	False	False

[songy23]

Finally was able to build a local agent (thanks to @dineshg13 !). Tested in staging that non top level OTLP spans also get trace metrics:

{
  "org_id":47678,
  "trace_id":"7817017947528822850",
  "span_id":"10739693701756824938",
  "parent_id":"15283232591715693939",
  "start":1682538833.124398,
  "end":1682538833.124401,
  "duration":0.000003291,
  "type":"http",
  "service":"java-test-app",
  "name":"TestSpan2",
  "resource":"TestSpan2",
  "resource_hash":"46bd36d900e12da6",
  "host_id":3013233129,
  "hostname":"COMP-YN6VVDJCY6",
  "env":"yang-otlp-test",
  "host_groups":[
    "env:yang-otlp-test"
  ],
  "meta":{
    "_dd.filter.type":"spans-sampling-processor",
    "_dd.agent_version":"7.45.0-rc.1+git.12.7d4dc82",
    "otel.status_code":"Unset",
    "env":"yang-otlp-test",
    "_dd.agent_rare_sampler.enabled":"false",
    "_dd.agent_hostname":"COMP-YN6VVDJCY6",
    "_dd.peer.service.source":"peer.service",
    "_dd.ingestion_reason":"otel",
    "_dd.p.dm":"-9",
    "span.kind":"client",
    "_dd.tracer_version":"otlp-",
    "_dd.filter.id":"w2wqZjVmSx22li16Kl5LDA",
    "otel.library.name":"io.opentelemetry.javaagent.spring",
    "peer.service":"peer-svc",
    "otel.library.version":"1.0.0",
    "_dd.hostname":"COMP-YN6VVDJCY6",
    "otel.trace_id":"ee5953f4ed09b50f6c7ba0682d4f0042",
    "deployment.environment":"yang-otlp-test"
  },
  "metrics":{
    "_dd.filter.kept":1,
    "_sampling_priority_v1":1,
    "_dd1.sr.esusr":1,
    "_dd.agent_errors_sampler.target_tps":10,
    "_top_level":1,
    "_dd.otlp_sr":1,
    "_dd.agent_priority_sampler.target_tps":10
  },
  "ingestion_reason":"otel",
  "children_ids":[
    
  ]
}