contrib/http/net: adding integration-level option to configure error codes

[rachelyangdog]

What does this PR do?

Closes #2882
Users want a way to configure error codes for http server spans generated from the net/http integration. If configured, these codes are the only codes that should be considered errors on relevant spans.

Motivation

Reviewer's Checklist

• Changed code has unit tests for its functionality at or near 100% coverage.
• System-Tests covering this feature have been added and enabled with the va.b.c-dev version tag.
• There is a benchmark for any new code, or changes to existing code.
• If this interacts with the agent in a new way, a system test has been added.
• Add an appropriate team label so this PR gets put in the right place for the release notes.
• Non-trivial go.mod changes, e.g. adding new modules, are reviewed by @DataDog/dd-trace-go-guild.
• For internal contributors, a matching PR should be created to the v2-dev branch and reviewed by @DataDog/apm-go.

Unsure? Have a question? Request a review!

[pr-commenter]

Benchmarks

Benchmark execution time: 2025-01-08 15:46:21

Comparing candidate commit 031dbfc in PR branch rachel.yang/http-net-error-codes with baseline commit 4f57a47 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 59 metrics, 0 unstable metrics.

[datadog-datadog-prod-us1]

Datadog Report

Branch report: rachel.yang/http-net-error-codes
Commit report: f3f533d
Test service: dd-trace-go

✅ 0 Failed, 5124 Passed, 70 Skipped, 2m 35.95s Total Time

[mtoffl01]

System test is failing because, with your changes, DD_TRACE_HTTP_SERVER_ERROR_STATUSES no longer applies to net/http.

When set, DD_TRACE_HTTP_SERVER_ERROR_STATUSES should impact all http integrations — this is kind of best effort, but for the purposes of this integration, let's say DD_TRACE_HTTP_SERVER_ERROR_STATUSES should impact all integrations that use contrib/internal/httptrace to start/finish spans.

However, if both DD_TRACE_HTTP_SERVER_ERROR_STATUSES and integration-level config WithStatusCheck are set, the former loses its effect and only the latter applies.

Make sure the system test passes by making sure DD_TRACE_HTTP_SERVER_ERROR_STATUSES applies to the net/http integration when WithStatusCheck has not been called. Take a look at contrib/go-chi for hints.

[mtoffl01]

LGTM, but make sure the PR title conforms to Go standards: https://github.com/DataDog/dd-trace-go/blob/main/CONTRIBUTING.md#contributing

[darccio]

LGTM

[mtoffl01]

Tiny nit, but really good work, good to merge!