Add tests for startup log behavior in tracer libraries

[bm1549]

Motivation

Add comprehensive tests for tracer startup log behavior across supported languages. These tests verify that tracers correctly emit startup configuration logs when DD_TRACE_STARTUP_LOGS=true and suppress them when DD_TRACE_STARTUP_LOGS=false, ensuring proper observability and configuration visibility.

Changes

Adds tests/parametric/test_startup_logs.py with three test cases:

1. test_startup_logs_enabled: Verifies that startup logs are emitted when DD_TRACE_STARTUP_LOGS=true

   • For Node.js: Triggers a trace to ensure startup logs are emitted (they appear when the tracer sends its first trace)
   • For .NET: Reads from the log file /dotnet-tracer-managed-ApmTestApi-1.log (startup logs are written to a file instead of stdout/stderr)
   • For other languages: Captures logs from container stdout/stderr
   • Validates presence of startup log pattern: DATADOG (TRACER )?CONFIGURATION( - (CORE|TRACING|PROFILING|.*))?
   • Marked as incomplete for php, cpp, and rust (need to figure out how to test these)

2. test_startup_logs_disabled: Verifies that startup logs are suppressed when DD_TRACE_STARTUP_LOGS=false

   • Uses the same checking behavior as the enabled test to ensure consistency
   • For Node.js: Triggers a trace to verify logs would be emitted if enabled
   • For .NET: Checks that the log file is empty or doesn't contain startup logs
   • For other languages: Verifies startup log pattern is not present in container logs
   • Marked as incomplete for php, cpp, and rust

3. test_startup_logs_diagnostic_agent_unreachable: Verifies diagnostic messages appear when the agent is unreachable

   • Tests that tracers output appropriate diagnostic messages when unable to connect to the agent
   • Searches for various diagnostic patterns (connection refused, DNS failures, etc.)
   • Marked as missing feature for cpp, rust, and dotnet (some tracers may not output diagnostic messages in startup logs)

The tests handle language-specific differences:

• Node.js requires trace triggering to emit startup logs
• .NET writes to a file instead of stdout/stderr
• Other languages output to stdout/stderr

Workflow

1. ⚠️ Create your PR as draft ⚠️
2. Work on you PR until the CI passes
3. Mark it as ready for review
   • Test logic is modified? -> Get a review from RFC owner.
   • Framework is modified, or non obvious usage of it -> get a review from R&P team

🚀 Once your PR is reviewed and the CI green, you can merge it!

🛟 #apm-shared-testing 🛟

Reviewer checklist

• Anything but tests/ or manifests/ is modified ? I have the approval from R&P team
• A docker base image is modified?
  • the relevant build-XXX-image label is present
• A scenario is added, removed or renamed?
  • Get a review from R&P team

[github-actions]

CODEOWNERS have been resolved as:

tests/parametric/test_startup_logs.py                                   @DataDog/system-tests-core @DataDog/apm-sdk-capabilities

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: f77dcff | Docs | Datadog PR Page | Was this helpful? Give us feedback!}