v1

server/metrics.py

@@ -0,0 +1,86 @@
+"""Metrics registry and helpers for Prometheus and JSON fallbacks."""
+from __future__ import annotations
+
+import logging
+import time
+from typing import Any, Dict, Tuple
+
+try:
+    from prometheus_client import CollectorRegistry, Counter, Histogram, generate_latest, CONTENT_TYPE_LATEST
+except Exception:
+    CollectorRegistry = None  # type: ignore
+    Counter = None  # type: ignore
+    Histogram = None  # type: ignore
+    generate_latest = None  # type: ignore
+    CONTENT_TYPE_LATEST = "text/plain; version=0.0.4; charset=utf-8"
+
+_start_time = time.time()
+_total_submissions = 0
+
+_prom_registry = CollectorRegistry() if CollectorRegistry is not None else None
+_prom_total_submissions = (
+    Counter("contact_total_submissions", "Total contact submissions", registry=_prom_registry)
+    if Counter is not None
+    else None
+)
+_prom_request_counter = None
+_prom_request_latency = None
+
+if Counter is not None and _prom_registry is not None:
+    try:
+        _prom_request_counter = Counter(
+            "http_requests_total",
+            "Total HTTP requests",
+            ["method", "endpoint"],
+            registry=_prom_registry,
+        )
+    except Exception:
+        _prom_request_counter = None
+
+if Histogram is not None and _prom_registry is not None:
+    try:
+        _prom_request_latency = Histogram(
+            "http_request_duration_seconds",
+            "Request duration",
+            ["method", "endpoint"],
+            registry=_prom_registry,
+        )
+    except Exception:
+        _prom_request_latency = None
+
+
+def record_submission() -> None:
+    """Register a completed contact submission."""
+    global _total_submissions
+    _total_submissions += 1
+    if _prom_total_submissions is not None:
+        try:
+            _prom_total_submissions.inc()
+        except Exception:
+            logging.debug("Failed to increment Prometheus submission counter", exc_info=True)
+
+
+def observe_request(method: str, endpoint: str, start_time: float | None, status: int | None = None) -> None:
+    """Update request counters and latency histograms."""
+    if _prom_request_counter is not None:
+        try:
+            _prom_request_counter.labels(method=method, endpoint=endpoint).inc()
+        except Exception:
+            logging.debug("Failed to increment request counter", exc_info=True)
+
+    if _prom_request_latency is not None and start_time:
+        try:
+            _prom_request_latency.labels(method=method, endpoint=endpoint).observe(time.time() - start_time)
+        except Exception:
+            logging.debug("Failed to observe request latency", exc_info=True)
+
+
+def export_metrics() -> Tuple[Any, int, Dict[str, str]]:
+    """Return a Flask-style response tuple for the metrics endpoint."""
+    uptime = int(time.time() - _start_time)
+    if generate_latest is not None and _prom_registry is not None:
+        payload = generate_latest(_prom_registry)
+        headers = {"Content-Type": CONTENT_TYPE_LATEST}
+        return payload, 200, headers
+    body = {"uptime_seconds": uptime, "total_submissions": _total_submissions}
+    return body, 200, {"Content-Type": "application/json"}