Updated alerting docs to give examples of some popular entity types

doc/Extensions/Alerting.md

@@ -1,17 +1,26 @@
 Table of Content:
+
 - [About](#about)
 - [Rules](#rules)
- - [Syntax](#rules-syntax)
- - [Examples](#rules-examples)
+    - [Syntax](#rules-syntax)
+    - [Examples](#rules-examples)
 - [Templates](#templates)
- - [Syntax](#templates-syntax)
- - [Examples](#templates-examples)
+    - [Syntax](#templates-syntax)
+    - [Examples](#templates-examples)
 - [Transports](#transports)
- - [E-Mail](#transports-email)
- - [API](#transports-api)
- - [Nagios-Compatible](#transports-nagios)
- - [IRC](#transports-irc)
- - [Slack](#transports-slack)
+    - [E-Mail](#transports-email)
+    - [API](#transports-api)
+    - [Nagios-Compatible](#transports-nagios)
+    - [IRC](#transports-irc)
+    - [Slack](#transports-slack)
+- [Entities](#entities)
+    - [Devices](#entity-devices)
+    - [BGP Peers](#entity-bgppeers)
+    - [IPSec Tunnels](#entity-ipsec)
+    - [Memory Pools](#entity-mempools)
+    - [Ports](#entity-ports)
+    - [Processors](#entity-processors)
+    - [Storage](#entity-storage)
 
 # <a name="about">About</a>
 
@@ -181,3 +190,83 @@ $config['alert']['transports']['slack'][] = array('url' => "https://hooks.slack.
 $config['alert']['transports']['slack'][] = array('url' => "https://hooks.slack.com/services/A12B34CDE/F56GH78JK/L901LmNopqrSTUVw2w3XYZAB4C", 'channel' => '@john', 'username' => 'LibreNMS', 'icon_emoji' => ':ghost:');
 
 ```
+
+# <a name="entities">Entities
+
+Entities as described earlier are based on the table and column names within the database, if you are ensure of what the entity is you want then have a browse around inside MySQL using `show tables` and `desc <tablename>`.
+
+## <a name="entity-devices">Devices</a>
+
+__devices.hostname__ = The devices hostname.
+
+__devices.location__ = The devices location.
+
+__devices.status__ = The status of the device, 1 = up, 0 = down.
+
+__devices.ignore__ = If the device is ignored this will be set to 1.
+
+__devices.disabled__ = If the device is disabled this will be set to 1.
+
+__devices.last_polled__ = The the last polled datetime (yyyy-mm-dd hh:mm:ss).
+
+__devices.type__ = The device type such as network, server, firewall, etc.
+
+## <a name="entity-bgppeers">BGP Peers</a>
+
+__bgpPeers.astext__ = This is the description of the BGP Peer.
+
+__bgpPeers.bgpPeerIdentifier__ = The IP address of the BGP Peer.
+
+__bgpPeers.bgpPeerRemoteAs__ = The AS number of the BGP Peer.
+
+__bgpPeers.bgpPeerState__ = The operational state of the BGP session.
+
+__bgpPeers.bgpPeerAdminStatus__ = The administrative state of the BGP session.
+
+__bgpPeers.bgpLocalAddr__ = The local address of the BGP session.
+
+## <a name="entity-ipsec">IPSec Tunnels</a>
+
+__ipsec_tunnels.peer_addr__ = The remote VPN peer address.
+
+__ipsec_tunnels.local_addr__ = The local VPN address.
+
+__ipsec_tunnels.tunnel_status__ = The VPN tunnels operational status.
+
+## <a name="entity-mempools">Memory pools</a>
+
+__mempools.mempool_type__ = The memory pool type such as hrstorage, cmp and cemp.
+
+__mempools.mempool_descr__ = The description of the pool such as Physical memory, Virtual memory and System memory.
+
+__mempools.mempool_perc__ = The used percentage of the memory pool.
+
+## <a name="entity-ports">Ports</a>
+
+__ports.ifDescr__ = The interface description.
+
+__ports.ifName__ = The interface name.
+
+__ports.ifSpeed__ = The port speed in bps.
+
+__ports.ifHighSpeed__ = The port speed in mbps.
+
+__ports.ifOperStatus__ = The operational status of the port (up or down).
+
+__ports.ifAdminStatus__ = The administrative status of the port (up or down).
+
+__ports.ifDuplex__ = Duplex setting of the port.
+
+__ports.ifMtu__ = The MTU setting of the port.
+
+## <a name="entity-processors">Processors</a>
+
+__processors.processor_usage__ = The usage of the processor as a percentage.
+
+__processors.processor_descr__ = The description of the processor.
+
+## <a name="entity-storage">Storage</a>
+
+__storage.storage_descr__ = The description of the storage.
+
+__storage.storage_perc__ = The usage of the storage as a percentage.