feat: email and webhook notification dispatch

fablednetmon/core/notifications.py

@@ -0,0 +1,100 @@
+from __future__ import annotations
+import asyncio
+import json
+import logging
+import smtplib
+import ssl
+import types
+from email.message import EmailMessage
+
+import httpx
+from jinja2 import Template
+
+logger = logging.getLogger(__name__)
+
+
+async def dispatch_notifications(
+    smtp_cfg: dict,
+    webhook_cfg: dict,
+    alert_data: dict,
+) -> dict:
+    """Dispatch all configured notification channels. Returns results dict."""
+    results = {}
+
+    if smtp_cfg.get("host") and smtp_cfg.get("recipients"):
+        results["email"] = await _send_email(smtp_cfg, alert_data)
+
+    if webhook_cfg.get("url"):
+        results["webhook"] = await _send_webhook(webhook_cfg, alert_data)
+
+    return results
+
+
+async def _send_email(cfg: dict, alert: dict) -> dict:
+    try:
+        msg = EmailMessage()
+        msg["Subject"] = f"[FabledNetMon] {alert['state']} — {alert['rule_name']}"
+        msg["From"] = cfg.get("username", "fablednetmon@localhost")
+        msg["To"] = ", ".join(cfg["recipients"])
+        msg.set_content(
+            f"Alert: {alert['state']}\n"
+            f"Rule: {alert['rule_name']}\n"
+            f"Resource: {alert['resource']}\n"
+            f"Metric: {alert['metric']} = {alert['value']}\n"
+            f"Threshold: {alert['threshold']}\n"
+            f"Time: {alert['timestamp']}\n"
+        )
+        loop = asyncio.get_running_loop()
+        await loop.run_in_executor(None, _smtp_send_sync, cfg, msg)
+        return {"sent": True, "error": None}
+    except Exception as exc:
+        logger.error(f"Email notification failed: {exc}")
+        return {"sent": False, "error": str(exc)}
+
+
+def _smtp_send_sync(cfg: dict, msg: EmailMessage) -> None:
+    ctx = ssl.create_default_context() if cfg.get("tls", True) else None
+    with smtplib.SMTP(cfg["host"], cfg.get("port", 587)) as smtp:
+        if ctx:
+            smtp.starttls(context=ctx)
+        if cfg.get("username"):
+            smtp.login(cfg["username"], cfg.get("password", ""))
+        smtp.send_message(msg)
+
+
+async def _send_webhook(cfg: dict, alert: dict) -> dict:
+    template_str = cfg.get(
+        "template",
+        '{"content": "{{ alert.state }} — {{ alert.rule_name }}"}',
+    )
+
+    # Render Jinja2 template with alert as a namespace object (attribute access)
+    try:
+        alert_ns = types.SimpleNamespace(**alert)
+        rendered = Template(template_str).render(alert=alert_ns)
+    except Exception as exc:
+        error = f"Template render failed: {exc}"
+        logger.error(error)
+        return {"sent": False, "error": error}
+
+    # Validate JSON before sending
+    try:
+        json.loads(rendered)
+    except json.JSONDecodeError as exc:
+        error = f"Rendered webhook template is not valid JSON: {exc}"
+        logger.error(error)
+        return {"sent": False, "error": error}
+
+    try:
+        async with httpx.AsyncClient(timeout=10) as client:
+            response = await client.post(
+                cfg["url"],
+                content=rendered,
+                headers={"Content-Type": "application/json"},
+            )
+            response.raise_for_status()
+        return {"sent": True, "error": None}
+    except Exception as exc:
+        error = str(exc)
+        logger.error(f"Webhook notification failed: {error}")
+        return {"sent": False, "error": error}

pyproject.toml

@@ -16,13 +16,13 @@ dependencies = [
     "pyyaml>=6.0",
     "packaging>=24.0",
     "click>=8.0",
+    "httpx>=0.27",
 ]
 
 [project.optional-dependencies]
 dev = [
     "pytest>=8.0",
     "pytest-asyncio>=0.23",
-    "httpx>=0.27",
 ]
 
 [project.scripts]