Example SNMP Trap handler class (#10311)

* Update SNMP-Traps.md

* Update SNMP-Traps.md

doc/Developing/SNMP-Traps.md

@@ -3,13 +3,77 @@ path: blob/master/doc/
 
 # Creating snmp trap handlers
 
-Create a new class in LibreNMS\Snmptrap\Handlers that implements the
-LibreNMS\Interfaces\SnmptrapHandler interface. 
+You must to have working snmptrapd. See [SNMP TRAP HANDLER](../Extensions/SNMP-Trap-Handler.md) 
 
-Register the mapping in the config/snmptraps.php file. Make sure to use the full trap oid.
+Make sure the MIB is loaded fro the trap you are adding. Edit `/etc/systemd/system/snmptrapd.service.d/mibs.conf` to add it then restart snmprtrapd.
+
+`MIBDIRS` option is not recursive, so you need to specify each directory individually.
+
+Create a new class in `LibreNMS\Snmptrap\Handlers` that implements the
+`LibreNMS\Interfaces\SnmptrapHandler` interface. For example:
 
 ```php
-'IF-MIB::linkUp' => \LibreNMS\Snmptrap\Handlers\LinkUp::class
+<?php
+/**
+ * ColdBoot.php
+ *
+ * Handles the SNMPv2-MIB::coldStart trap
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @package    LibreNMS
+ * @link       http://librenms.org
+ */
+
+namespace LibreNMS\Snmptrap\Handlers;
+
+use App\Models\Device;
+use LibreNMS\Interfaces\SnmptrapHandler;
+use LibreNMS\Snmptrap\Trap;
+use Log;
+
+class ColdBoot implements SnmptrapHandler
+{
+    /**
+     * Handle snmptrap.
+     * Data is pre-parsed and delivered as a Trap.
+     *
+     * @param Device $device
+     * @param Trap $trap
+     * @return void
+     */
+    public function handle(Device $device, Trap $trap)
+    {
+        Log::event('SNMP Trap: Device ' . $device->displayName() . ' cold booted', $device->device_id, 'reboot', 4);
+    }
+}
+
+```
+
+where number on the end of the row `Log::event` means color of the eventlog:
+```
+1 green
+2 cyan
+3 blue
+4 yellow
+5 red 
+```
+
+Register the mapping in the `config/snmptraps.php` file. Make sure to use the full trap oid and correct class.
+
+```php
+'SNMPv2-MIB::coldStart' => \LibreNMS\Snmptrap\Handlers\ColdBoot::class,
 ```
 
 The handle function inside your new class will receive a LibreNMS/Snmptrap/Trap