[mashkovd]

Found during the synthetic span proof after #1764 (2026-10-10).

The live otel-collector (0.160) exposes the Tempo exporter's telemetry as exporter="otlp_grpc/eval-tempo", the resolved type, not the config ID otlp/eval-tempo:

otelcol_exporter_sent_spans{exporter="debug"}                 72
otelcol_exporter_sent_spans{exporter="otlp_grpc/eval-tempo"}  72

TempoEvalCollectorExportFailures and TempoEvalCollectorDroppedSpans selected exporter="otlp/eval-tempo", so they had no series to evaluate and could never fire. The unit tests fed the same wrong label, so they passed anyway.

Changes:

• Both rules now select exporter=~"otlp(_grpc)?/eval-tempo", so a collector upgrade that changes the alias cannot silently blind them.
• The tests feed the real label otlp_grpc/eval-tempo. The "other exporter stays quiet" cases are unchanged.
• The runbook's verification queries use the real label, with a note.

Verified both ways with scripts/check-vm-rules.sh (promtool): green with this change, and export failures to Tempo fire goes red when the old exact selector is restored against the real label.

Refs #1280

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https://claude.ai/code/session_013zqBqP9sSbVTd1kXRLA6AU

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[claude]

Claude finished @mashkovd's task in 1m 9s —— View job

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Review: tempo eval collector exporter label fix

• Gather context (diff 403f0771...9a04c699, runbook, VMRule, and test file)
• Verify the regex selector matches the real collector label without widening to other exporters
• Check runbook/test consistency with the new label
• Post findings and submit verdict

Analysis

The fix is sound. otlp(_grpc)?/eval-tempo is a correctly anchored regex matcher (VM/Prometheus =~ is full-string match), so it catches both the config ID (otlp/eval-tempo) and the collector's resolved-type label (otlp_grpc/eval-tempo) without matching unrelated exporters — confirmed the "different exporter stays quiet" test still uses otlp/backend, which the new pattern doesn't touch.

Tests in tempo-eval-alerts_test.yaml now feed the real otlp_grpc/eval-tempo label for both TempoEvalCollectorExportFailures and TempoEvalCollectorDroppedSpans, matching the annotation text update. Runbook verification queries and the scoring table were updated to the same real label.

One pre-existing line not touched by this diff (tempo-eval-alerts.yaml:7, file-level header comment: "...the otlp/eval-tempo exporter") is now slightly stale since the selector matches two labels — not part of this diff's hunks so no inline comment was possible, purely optional follow-up.

No P1/P2 findings. 0 P3 (the header-comment note above is informational, not a blocking nit).

[github-actions]

Antigravity (agy) review — informational

Model: gemini-3.8-flash-medium · commit 9a04c69.

No significant issues found.

[claude]

No P1/P2 findings (0 P3). Regex selector correctly matches both the config-ID and collector-resolved exporter labels without widening to other exporters; tests and runbook updated to the real label. Good to merge.