Files
familienarchiv/ocr-service/metrics.py
Marcel f3e3545d06 feat(ocr): add metrics.py factory with test-scoped CollectorRegistry support
Encapsulates every custom OCR metric in an OcrMetrics frozen dataclass and
exposes a `build_metrics(registry)` factory. Production main.py binds against
the default REGISTRY; tests construct a fresh CollectorRegistry per case and
monkeypatch main.metrics, so counter values stay isolated between tests
(decision #3 on issue #652, Option A).

Refs #652

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-05-21 16:02:20 +02:00

93 lines
3.2 KiB
Python

"""Prometheus metric definitions for the OCR service.
`build_metrics(registry)` returns a fresh `OcrMetrics` instance bound to the
given `CollectorRegistry`. Production code calls it once at module load with
the default `REGISTRY`; tests pass a per-test `CollectorRegistry()` to keep
counter values isolated between cases (decision #3 on issue #652).
"""
from __future__ import annotations
from dataclasses import dataclass
from prometheus_client import CollectorRegistry, Counter, Gauge, Histogram
@dataclass(frozen=True)
class OcrMetrics:
"""Container for every custom OCR metric.
Counters and gauges are immutable references to `prometheus_client`
instances. Mutating them (`.inc()`, `.observe()`, `.set()`) is safe;
rebinding the field on the dataclass is not — use `build_metrics` to get
a new container.
"""
ocr_jobs_total: Counter
ocr_pages_total: Counter
ocr_skipped_pages_total: Counter
ocr_words_total: Counter
ocr_illegible_words_total: Counter
ocr_processing_seconds: Histogram
ocr_training_runs_total: Counter
ocr_model_accuracy: Gauge
ocr_models_ready: Gauge
def build_metrics(registry: CollectorRegistry) -> OcrMetrics:
"""Create one OcrMetrics instance bound to `registry`."""
return OcrMetrics(
ocr_jobs_total=Counter(
"ocr_jobs_total",
"Number of OCR jobs processed, labelled by engine and script type.",
["engine", "script_type"],
registry=registry,
),
ocr_pages_total=Counter(
"ocr_pages_total",
"Number of pages successfully OCR'd, labelled by engine.",
["engine"],
registry=registry,
),
ocr_skipped_pages_total=Counter(
"ocr_skipped_pages_total",
"Number of pages skipped because the OCR engine raised.",
registry=registry,
),
ocr_words_total=Counter(
"ocr_words_total",
"Number of words recognized across all OCR blocks.",
registry=registry,
),
ocr_illegible_words_total=Counter(
"ocr_illegible_words_total",
"Number of words below the confidence threshold "
"(replaced with [unleserlich]).",
registry=registry,
),
ocr_processing_seconds=Histogram(
"ocr_processing_seconds",
"OCR processing time per page (streaming) or per document (non-streaming).",
["engine"],
registry=registry,
),
ocr_training_runs_total=Counter(
"ocr_training_runs_total",
"Number of training runs, labelled by kind (recognition|segmentation) "
"and outcome (success|error).",
["kind", "outcome"],
registry=registry,
),
ocr_model_accuracy=Gauge(
"ocr_model_accuracy",
"Latest model accuracy reported by a successful training run.",
["kind"],
registry=registry,
),
ocr_models_ready=Gauge(
"ocr_models_ready",
"1 once the lifespan startup has finished loading models, 0 before.",
registry=registry,
),
)