fix(alerts): expose alertmanager webhook request metrics

apps/api/src/api/v1/webhooks.py

@@ -25,6 +25,7 @@ Endpoints:
 import asyncio
 import hashlib
 import hmac
+import time
 import uuid
 from typing import Literal
 
@@ -34,7 +35,7 @@ from pydantic import BaseModel, Field
 from src.core.config import settings
 from src.core.constants import is_cicd_alertname, is_heartbeat_alertname
 from src.core.logging import get_logger
-from src.core.metrics import record_alert_chain_success
+from src.core.metrics import record_alert_chain_success, record_webhook_request
 from src.models.approval import (
     ApprovalRequestCreate,
     BlastRadius,
@@ -2606,6 +2607,27 @@ async def alertmanager_webhook(
     - 內網 IP (192.168.x.x, 10.x.x.x, 172.x.x.x): 免 HMAC
     - 外網 IP: 拒絕
     """
+    metric_started_at = time.monotonic()
+    metric_recorded = False
+
+    def _record_webhook_metric(metric_status: str) -> None:
+        nonlocal metric_recorded
+        if metric_recorded:
+            return
+        metric_recorded = True
+        try:
+            record_webhook_request(
+                "alertmanager",
+                metric_status,
+                time.monotonic() - metric_started_at,
+            )
+        except Exception as metric_err:
+            logger.warning(
+                "alertmanager_webhook_metric_record_failed",
+                status=metric_status,
+                error=str(metric_err),
+            )
+
     # 取得客戶端 IP
     client_ip = request.client.host if request.client else "unknown"
     forwarded_for = request.headers.get("X-Forwarded-For", "").split(",")[0].strip()
@@ -2618,6 +2640,7 @@ async def alertmanager_webhook(
             client_ip=actual_ip,
             reason="External IP must use /alerts with HMAC",
         )
+        _record_webhook_metric("error")
         raise HTTPException(
             status_code=status.HTTP_403_FORBIDDEN,
             detail="External sources must use /alerts endpoint with HMAC signature",
@@ -2633,6 +2656,7 @@ async def alertmanager_webhook(
     # 只處理第一個 firing 告警 (避免告警風暴)
     firing_alerts = [a for a in payload.alerts if a.status == "firing"]
     if not firing_alerts:
+        _record_webhook_metric("success")
         return AlertResponse(
             success=True,
             message="No firing alerts to process",
@@ -2712,6 +2736,7 @@ async def alertmanager_webhook(
             )
 
             record_alert_chain_success("alertmanager")
+            _record_webhook_metric("success")
             return AlertResponse(
                 success=True,
                 message=f"CI/CD alert processed (simple format): {alertname}",
@@ -2721,6 +2746,7 @@ async def alertmanager_webhook(
         except Exception as e:
             logger.error("cicd_telegram_failed", error=str(e), alertname=alertname)
             # CI/CD 通知失敗不阻擋流程
+            _record_webhook_metric("success")
             return AlertResponse(
                 success=True,
                 message=f"CI/CD alert logged (telegram failed): {alertname}",
@@ -2866,6 +2892,7 @@ async def alertmanager_webhook(
             parent_fingerprint=grouping_result.parent_fingerprint,
             fingerprint=fingerprint,
         )
+        _record_webhook_metric("success")
         return AlertResponse(
             success=True,
             message=(
@@ -2940,6 +2967,7 @@ async def alertmanager_webhook(
                     notification_type=notification_type,
                 )
 
+                _record_webhook_metric("success")
                 return AlertResponse(
                     success=True,
                     message=f"🛡️ 告警收斂 (x{updated_approval.hit_count}) - 已排程節流再通知",
@@ -3004,6 +3032,7 @@ async def alertmanager_webhook(
                 severity=severity,
             )
             record_alert_chain_success("alertmanager")
+            _record_webhook_metric("success")
             return AlertResponse(
                 success=True,
                 message="✅ TYPE-1 純資訊告警已通知 (no LLM)",
@@ -3050,6 +3079,7 @@ async def alertmanager_webhook(
                 notification_type=notification_type,
                 recurrence_stage="llm_inflight",
             )
+            _record_webhook_metric("success")
             return AlertResponse(
                 success=True,
                 message="🛡️ 告警已由同指紋背景 AI 分析處理中，已排程節流再通知",
@@ -3096,6 +3126,7 @@ async def alertmanager_webhook(
         )
 
         record_alert_chain_success("alertmanager")
+        _record_webhook_metric("success")
         return AlertResponse(
             success=True,
             message="✅ 告警已排入背景分析 (202 Accepted)",
@@ -3110,6 +3141,7 @@ async def alertmanager_webhook(
             fingerprint=fingerprint,
             error=str(e),
         )
+        _record_webhook_metric("error")
         return AlertResponse(
             success=False,
             message="⚠️ 告警已接收但處理降級，避免 Alertmanager retry storm；已交由背景治理/人工介入追蹤",