feat: add Nagios monitoring provider

docs/mint.json

@@ -212,6 +212,7 @@
             "providers/documentation/monday-provider",
             "providers/documentation/mongodb-provider",
             "providers/documentation/mysql-provider",
+            "providers/documentation/nagios-provider",
             "providers/documentation/netbox-provider",
             "providers/documentation/netdata-provider",
             "providers/documentation/new-relic-provider",

docs/providers/documentation/nagios-provider.mdx

@@ -0,0 +1,34 @@
+---
+title: "Nagios"
+sidebarTitle: "Nagios Provider"
+description: "Nagios provider allows you to get alerts from Nagios into Keep by pulling host and service status, or receiving webhook notifications."
+---
+import AutoGeneratedSnippet from '/snippets/providers/nagios-snippet-autogenerated.mdx';
+
+<AutoGeneratedSnippet />
+
+## Connecting with the Provider
+
+### Option 1: Pull-based (Nagios XI API)
+
+1. You need a Nagios XI instance with API access enabled.
+2. Go to **Admin > Manage API Keys** and create a new API key.
+3. Use the Nagios XI URL and the API key to configure the provider.
+
+### Option 2: Push-based (Webhook)
+
+1. Configure a notification command in Nagios that sends HTTP POST requests to Keep.
+2. Assign the command to a contact and configure notification rules.
+3. See the webhook setup instructions in the provider configuration for details.
+
+## Useful Links
+
+- [Nagios](https://www.nagios.org/)
+- [Nagios XI REST API](https://www.nagios.org/documentation/)
+- [Nagios Core Plugin API](https://assets.nagios.com/downloads/nagioscore/docs/nagioscore/4/en/pluginapi.html)
+
+## Notes
+
+- The provider supports both Nagios XI (with REST API) for pulling alerts, and webhook-based notifications for push-based alerting.
+- Host states: UP (0), DOWN (1), UNREACHABLE (2)
+- Service states: OK (0), WARNING (1), CRITICAL (2), UNKNOWN (3)

keep/providers/nagios_provider/alerts_mock.py

@@ -0,0 +1,11 @@
+ALERTS = {
+    "host_name": "webserver01",
+    "host_state": "DOWN",
+    "host_address": "192.168.1.100",
+    "service_desc": "HTTP",
+    "service_state": "CRITICAL",
+    "service_output": "CRITICAL - Socket timeout after 10 seconds",
+    "long_service_output": "Connection to 192.168.1.100:80 timed out",
+    "notification_type": "PROBLEM",
+    "timestamp": "1706000000",
+}