feat: implement persistent audit logging for import/export operations with Prometheus metrics

monitoring/__init__.py

@@ -0,0 +1,13 @@
+from __future__ import annotations
+
+from fastapi import APIRouter, Response
+from prometheus_client import CONTENT_TYPE_LATEST, generate_latest
+
+
+router = APIRouter(prefix="/metrics", tags=["monitoring"])
+
+
+@router.get("", summary="Prometheus metrics endpoint", include_in_schema=False)
+async def metrics_endpoint() -> Response:
+    payload = generate_latest()
+    return Response(content=payload, media_type=CONTENT_TYPE_LATEST)

monitoring/metrics.py

@@ -0,0 +1,42 @@
+from __future__ import annotations
+
+from typing import Iterable
+
+from prometheus_client import Counter, Histogram
+
+IMPORT_DURATION = Histogram(
+    "calminer_import_duration_seconds",
+    "Duration of import preview and commit operations",
+    labelnames=("dataset", "action", "status"),
+)
+
+IMPORT_TOTAL = Counter(
+    "calminer_import_total",
+    "Count of import operations",
+    labelnames=("dataset", "action", "status"),
+)
+
+EXPORT_DURATION = Histogram(
+    "calminer_export_duration_seconds",
+    "Duration of export operations",
+    labelnames=("dataset", "status", "format"),
+)
+
+EXPORT_TOTAL = Counter(
+    "calminer_export_total",
+    "Count of export operations",
+    labelnames=("dataset", "status", "format"),
+)
+
+
+def observe_import(action: str, dataset: str, status: str, seconds: float) -> None:
+    IMPORT_TOTAL.labels(dataset=dataset, action=action, status=status).inc()
+    IMPORT_DURATION.labels(dataset=dataset, action=action,
+                           status=status).observe(seconds)
+
+
+def observe_export(dataset: str, status: str, export_format: str, seconds: float) -> None:
+    EXPORT_TOTAL.labels(dataset=dataset, status=status,
+                        format=export_format).inc()
+    EXPORT_DURATION.labels(dataset=dataset, status=status,
+                           format=export_format).observe(seconds)