Add OTelMetricsExporter step for OTLP metrics export by davesh0812 · Pull Request #641 · mlrun/storey

davesh0812 · 2026-05-05T18:11:24Z

Summary

Adds OTelMetricsExporter, a pass-through pipeline step that exports user-defined domain metrics via OTLP gRPC as a side-effect, forwarding events downstream unchanged
Supports all 4 OTel synchronous instrument types: gauge, counter, updown_counter, histogram; both periodic and immediate flush modes; single and multi-metric events; configurable field mapping
Install with pip install storey[otel]

Design notes

Not a target — pass-through only.
OTelMetricsExporter is a mid-pipeline step, not a terminal target. Every event is forwarded downstream unchanged after the metric is recorded. This allows metrics export to be composed with any downstream step (e.g. ParquetTarget, Map, etc.).

No ACK / delivery guarantee — by design.
Export is best-effort, matching the standard OTel contract. The OTel SDK handles batching, retries, and delivery to the collector internally. A failed export cycle does not block, error, or retry the event in the Storey pipeline. This is consistent with how every other OTel SDK integration works — the pipeline should not be coupled to metrics delivery.

Test plan

Unit tests: pytest tests/test_otel_metrics_exporter.py (39 tests, mock OTLP exporter)
Integration tests: pytest integration/test_otel_metrics_exporter.py (15 tests, embedded in-process gRPC receiver, no Docker required)
All 4 instrument types × both flush modes covered
Mixed-type multi-metric events covered

🤖 Generated with Claude Code

Introduces OTelMetricsExporter, a pass-through Storey step that records OpenTelemetry metrics from event body fields as a side-effect and forwards each event downstream unchanged. - Supports all 4 synchronous OTel instrument types: gauge (set), counter (add), updown_counter (add), histogram (record) - Both flush modes: periodic (background timer) and immediate (force_flush after every event via run_in_executor) - Single and multi-metric events; per-metric instrument type override via event body field - Configurable field mapping: metric_name_field, value_field, attribute_fields, metrics_field, instrument_type_field - Lazy MeterProvider init on first event; force_flush + shutdown on termination - install: pip install storey[otel] 54 tests: 39 unit (mock exporter) + 15 integration (in-process gRPC receiver, no Docker required), covering all 4 types x both flush modes. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Copilot

Pull request overview

Adds an OpenTelemetry metrics exporting step to Storey pipelines (OTelMetricsExporter) that records metrics as a side effect while forwarding events downstream unchanged, plus unit/integration tests and an optional storey[otel] dependency group.

Changes:

Introduces OTelMetricsExporter with support for gauge/counter/updown_counter/histogram and immediate vs periodic flush modes.
Exposes the step via storey.__init__ and adds otel extras for OpenTelemetry SDK + OTLP gRPC exporter.
Adds comprehensive unit tests (mock exporter) and integration tests (embedded in-process OTLP gRPC receiver).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
`storey/otel_metrics_exporter.py`	New Flow step that records metrics and exports via OTLP gRPC (side-effect), then passes events through.
`storey/__init__.py`	Exposes `OTelMetricsExporter` from the package top-level.
`setup.py`	Adds `storey[otel]` optional dependencies for OpenTelemetry metrics + OTLP gRPC exporter.
`tests/test_otel_metrics_exporter.py`	Unit tests for instrument dispatch, validation, pass-through behavior, termination behavior, and field mapping.
`integration/test_otel_metrics_exporter.py`	End-to-end tests using an embedded OTLP gRPC receiver (no Docker).

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Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

…erver teardown - Validate per-event instrument type in _register_instrument before creating instrument - Replace math.inf with sys.maxsize for export_interval_millis in immediate mode - Bind integration test gRPC server to port 0 (dynamic) to avoid port conflicts - Call .wait() on server.stop() to ensure full teardown before next test Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Copilot

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

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- Wrap force_flush/shutdown in try/except so termination never raises - Validate export_interval_millis and max_instruments are positive in __init__

This reverts commit bee3a66.

royischoss

hey small comments

royischoss · 2026-05-10T09:30:51Z

+            return
+        if OTLPMetricExporter is None:
+            raise ImportError("Install with: pip install storey[otel]")
+        interval = sys.maxsize if self._flush_mode == "immediate" else self._export_interval_millis


sys.maxsize as interval for immediate mode — using an astronomically large interval to suppress periodic exports is a hack. The OTel SDK provides ManualReader precisely for this case and makes the intent explicit

from opentelemetry.sdk.metrics.export import ManualMetricReader

if self._flush_mode == "immediate":
reader = ManualMetricReader(exporter)
else:
reader = PeriodicExportingMetricReader(exporter, export_interval_millis=self._export_interval_millis)

immediate mode: force_flush per event is expensive — calling force_flush(timeout_millis=5_000) on every single event will be a throughput killer. The docstring should warn that immediate mode is intended for low-volume /
debugging scenarios, and periodic is the recommended default for production.

Missing required field raises KeyError, not ValueError — if metric_name_field or value_field is absent from the event body, the user gets a raw KeyError. A ValueError with a clear message about which field is missing would be
more helpful.

There is no ManualMetricReader I used math.inf like they metntion on :

OpenTelemetry Python SDK metrics.export docs (https://opentelemetry-python.readthedocs.io/en/latest/sdk/metrics.export.html)

opentelemetry-python v1.41.1 source (https://github.com/open-telemetry/opentelemetry-python/blob/v1.41.1/opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/export/__init__.py)

…g fields - Replace sys.maxsize hack with math.inf to disable periodic collection (officially documented PeriodicExportingMetricReader behavior). - Log shutdown failures via self.logger (fall back to print) instead of silently swallowing exceptions. - Raise ValueError naming the missing field instead of bare KeyError when metric_name_field or value_field is absent from the event body. - Document that flush_mode="immediate" is intended for low-volume or debugging use only. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

royischoss

LGTM 🔥

davesh0812 requested a review from Copilot May 5, 2026 18:12

Copilot started reviewing on behalf of davesh0812 May 5, 2026 18:12 View session

Fix flake8 lint errors in OTelMetricsExporter files

cf7f9c6

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Copilot AI reviewed May 5, 2026

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Comment thread storey/otel_metrics_exporter.py

Comment thread storey/otel_metrics_exporter.py

Comment thread integration/test_otel_metrics_exporter.py Outdated

Comment thread integration/test_otel_metrics_exporter.py Outdated

David Schneider and others added 4 commits May 5, 2026 21:20

Apply black formatting to OTelMetricsExporter files

7610466

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Fix isort import ordering in OTelMetricsExporter files

02216aa

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Fix isort ordering for OTelMetricsExporter in __init__.py

bd7f8aa

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

davesh0812 requested a review from Copilot May 5, 2026 18:37

Copilot started reviewing on behalf of davesh0812 May 5, 2026 18:38 View session

davesh0812 changed the title ~~Add OTelMetricsExporter pass-through step for OTLP metrics export~~ Add OTelMetricsExporter step for OTLP metrics export May 5, 2026

Copilot AI reviewed May 5, 2026

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Comment thread storey/otel_metrics_exporter.py Outdated

Comment thread storey/otel_metrics_exporter.py Outdated

Comment thread storey/otel_metrics_exporter.py

Comment thread storey/otel_metrics_exporter.py

Comment thread integration/test_otel_metrics_exporter.py

David Schneider and others added 3 commits May 6, 2026 10:02

Address Copilot review: best-effort teardown and input validation

e14552d

- Wrap force_flush/shutdown in try/except so termination never raises - Validate export_interval_millis and max_instruments are positive in __init__

dummy commit to test user

bee3a66

Revert "dummy commit to test user"

6b692fa

This reverts commit bee3a66.

royischoss reviewed May 10, 2026

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davesh0812 and others added 2 commits May 10, 2026 13:08

Apply black formatting

ca2f4ec

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

royischoss approved these changes May 10, 2026

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davesh0812 merged commit 24e0040 into mlrun:development May 10, 2026
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davesh0812 commented May 5, 2026 •

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