add Icinga2 configuration

_toc.yml

@@ -33,6 +33,7 @@ chapters:
           - file: admin-guide/architecture/active-directory
       - file: admin-guide/configuration
         sections:
+          - file: admin-guide/configuration/icinga2
           - file: admin-guide/configuration/distribute_files
           - file: admin-guide/configuration/vgroot
           - file: admin-guide/configuration/xrdp

admin-guide/configuration.md

@@ -2,6 +2,9 @@
 
 Here starts a so far small collections of configuration guides for sysadmins of RHEL installations using Puppet and Hiera.
 
+## Monitoring
+- [Icinga2](configuration/icinga2)
+
 ## Basic Setup
 - [Distribute Files](configuration/distribute_files)
 - [RDP Remote Access with XRDP](configuration/xrdp)

admin-guide/configuration/icinga2.md

@@ -0,0 +1,19 @@
+# Icinga2
+
+**this is very much work in progress**
+
+The overview of your nodes in Icinga2 you get at [monitoring.psi.ch](https://monitoring.psi.ch) and there you can handle the alerts and create service windows, etc.
+
+But the configuration as such is not done therein, but in Hiera and automatically propagated.
+
+
+## Basic Configuration
+Enable monitoring with Icinga2 by
+
+```
+icinga2::enable: true
+```
+(which will be default at some point, e.g. for RHEL9).
+
+Users and groups in `aaa::admins` and `icinga2::web::users` will have access to these nodes on [monitoring.psi.ch](https://monitoring.psi.ch).
+