feat(telemetry)!: configure traces via universal OTel env vars (RFC 0038 slice 4 → green)

[jensholdgaard]

RFC 0038 slice 4 — traces via universal OTel env vars (RFC 0038 → green)

The last slice. It deletes the bespoke sampler-config coupling and leans traces entirely on the standard OpenTelemetry SDK env vars — the config contract operators already know.

Changes

• Sampler: drop TelemetryConfig.trace_sample_ratio and the forced .with_sampler() in init(). SdkTracerProvider::builder() seeds its config from an env-reading Config::default(), so not setting a sampler means the SDK resolves OTEL_TRACES_SAMPLER / OTEL_TRACES_SAMPLER_ARG (default parentbased_always_on). Invalid values are logged + ignored by the SDK per the env-var spec — no bespoke validation or file-vs-env precedence.
• Disable: the standard per-signal switch OTEL_TRACES_EXPORTER=none, mapped in the server (traces_enabled() helper) to traces_enabled=false — the one programmatic flag the library keeps. OTEL_SDK_DISABLED still turns off all three signals together.
• §3.4 amended to this universal-env-var approach (no telemetry.traces.* config-file section, no precedence, no hand-rolled validation).

Tests (RFC0038.4)

rfc0038_4_otel_traces_exporter_none_disables_traces (server unit): OTEL_TRACES_EXPORTER → install decision (none off; unset / otlp / other on). Sampler resolution is the SDK's universal, upstream-tested behaviour that Ourios no longer overrides — nothing Ourios-specific left to test there.

RFC 0038 is now green

All six §5 criteria pass — RFC0038.1 (#614/#615/#616/#617), .2 (#615), .3 (#617), .4 (this PR), .5/.6 (#614). Status flipped specified → green.

Follow-up

Metrics + logs carry the same coupling (export_interval vs OTEL_METRIC_EXPORT_INTERVAL; no OTEL_METRICS_EXPORTER/OTEL_LOGS_EXPORTER=none) — tracked in #618.

BREAKING CHANGE: TelemetryConfig.trace_sample_ratio removed; sampling is now the standard OTEL_TRACES_SAMPLER/_ARG env vars.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • Trace collection can now be disabled with OTEL_TRACES_EXPORTER=none, regardless of capitalization or surrounding whitespace.
  • Trace sampling now follows standard OpenTelemetry environment variables, including OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG.
  • Default and other supported exporter settings continue to enable tracing.

• Documentation

  • Updated self-tracing guidance and configuration examples to reflect environment-based setup and current behavior.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: ee4eae7b-3111-4249-8697-3ef8f2b32f43

📥 Commits

Reviewing files that changed from the base of the PR and between 752b301 and a0c1013.

📒 Files selected for processing (1)

• crates/ourios-server/src/main.rs

📝 Walkthrough

Walkthrough

Telemetry sampling is delegated to standard OTel environment variables. Server startup disables the traces pipeline only for OTEL_TRACES_EXPORTER=none, and RFC0038 documents the updated configuration contract and acceptance criteria.

Changes

OTel trace configuration

Layer / File(s)	Summary
Telemetry sampler contract crates/ourios-telemetry/src/lib.rs	Removes TelemetryConfig.trace_sample_ratio and custom sampler selection, allowing OTel environment variables to resolve sampling.
Server trace activation crates/ourios-server/src/main.rs	Maps OTEL_TRACES_EXPORTER to trace pipeline activation and tests case-insensitive, whitespace-trimmed none handling.
RFC0038 configuration contract docs/rfcs/0038-self-tracing.md	Marks the RFC green and replaces the file-based tracing configuration guidance with OTel environment-variable behavior.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• jensholdgaard/ourios#613: Introduced the earlier RFC0038 self-tracing configuration guidance updated by this PR.
• jensholdgaard/ourios#614: Introduced the tracing setup that this PR changes to use exporter-based activation and OTel sampler configuration.
• jensholdgaard/ourios#615: Also modifies shared telemetry initialization under the traces_enabled path.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main change: moving traces to standard OTel env vars and marking the RFC slice green.
Description check	✅ Passed	The description covers the summary, related context, tests, RFC status, and breaking change, so it is mostly complete despite missing the template checklist.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch rfc-0038-config

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[Copilot]

Pull request overview

This PR completes RFC 0038 slice 4 by removing the bespoke trace-sampler configuration surface and delegating trace sampling entirely to the OpenTelemetry SDK’s standard environment variables, while mapping the standard OTEL_TRACES_EXPORTER=none switch to disabling trace installation in Ourios. It also updates RFC 0038’s status to green and amends §3.4 accordingly.

Changes:

• Remove TelemetryConfig.trace_sample_ratio and stop forcing a sampler in ourios-telemetry so sampling is resolved via OTEL_TRACES_SAMPLER / OTEL_TRACES_SAMPLER_ARG.
• Add server-side mapping OTEL_TRACES_EXPORTER=none → TelemetryConfig.traces_enabled=false, with a unit test for the mapping behavior.
• Update RFC 0038 documentation to reflect the universal-env-var approach and mark the RFC as green.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/rfcs/0038-self-tracing.md	Marks RFC 0038 as green and updates §3.4 + RFC0038.4 scenario to use universal OTel env vars.
crates/ourios-telemetry/src/lib.rs	Drops the custom sampler knob and stops overriding sampler selection so the SDK can resolve it from env.
crates/ourios-server/src/main.rs	Adds OTEL_TRACES_EXPORTER=none → disable mapping (traces_enabled()), wires it into startup, and tests it.

Comments suppressed due to low confidence (1)

crates/ourios-server/src/main.rs:958

• This assertion message reads like otlp,console is a supported exporter configuration, but Ourios only uses this env var to detect the special none disable value. Consider rewording the message so it doesn’t imply other exporter selectors are honored.

        assert!(traces_enabled(Some("otlp")), "otlp → on");
        assert!(traces_enabled(Some("otlp,console")), "a real exporter → on");
        assert!(!traces_enabled(Some("none")), "none → off");

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/ourios-telemetry/src/lib.rs`:
- Around line 294-308: Add a crate-local unit test adjacent to init that sets
OTEL_TRACES_SAMPLER and OTEL_TRACES_SAMPLER_ARG in isolation, initializes
tracing, and verifies the resulting sampler follows those environment settings
rather than a hard-coded value. Use an in-memory exporter or isolated process
and restore environment state to keep the test independent.
- Around line 294-308: Update the shared SDK initialization in
crates/ourios-telemetry/src/lib.rs around the logger and tracer provider
construction to check OTEL_SDK_DISABLED=true first and route both signals
through a common no-op path without constructing exporters or providers; add
tests covering all-signals-disabled behavior. In
crates/ourios-server/src/main.rs lines 813-818, propagate the setting instead of
only mapping OTEL_TRACES_EXPORTER. Update docs/rfcs/0038-self-tracing.md lines
158-180 to preserve the documented all-signals no-op contract.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 14df65d4-8380-48de-9999-c69fdb876e8a

📥 Commits

Reviewing files that changed from the base of the PR and between 59f718c and 752b301.

📒 Files selected for processing (3)

• crates/ourios-server/src/main.rs
• crates/ourios-telemetry/src/lib.rs
• docs/rfcs/0038-self-tracing.md

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.