Fixed problem with SNMP version change and added log message when changing interface type.

README.md

@@ -21,7 +21,7 @@ A script to sync the Netbox device inventory to Zabbix.
 
 
 #### Logging
-Logs are generated under sync.log, set the script for debugging / info options etc.
+Logs are generated under sync.log, use -v for debugging.
 
 #### Hostgroups: manual mode
 
@@ -52,6 +52,63 @@ And this field for the Zabbix template
 * Default: null
 * Object: dcim > device_type
 
+#### Set interface parameters within Netbox
+When adding a new device, you can set the interface type with custom context.
+Due to Zabbix limitations of changing interface type with a linked template, changing the interface type from within Netbox is not supported and the script will generate an error.
+
+For example when changing a SNMP interface to an Agent interface:
+```
+Netbox-Zabbix-sync - WARNING - Device: Interface OUT of sync.
+Netbox-Zabbix-sync - ERROR - Device: changing interface type to 1 is not supported.
+```
+
+To configure the interface parameters you'll need to use custom context. Custom context was used to make this script as customizable as posible for each environment. For example, you could:
+ * Set the custom context directly on a device
+ * Set the custom context on a label, which you would add to a device (for instance, SNMPv3)
+ * Set the custom context on a device role
+ * Set the custom context on a site or region
+
+##### Agent interface configuration example
+```json
+{
+    "zabbix": {
+        "interface_port": 1500,
+        "interface_type": 1
+    }
+}
+```
+##### SNMPv2 interface configuration example
+```json
+{
+    "zabbix": {
+        "interface_port": 161,
+        "interface_type": 2,
+        "snmp": {
+            "bulk": 1,
+            "community": "SecretCommunity",
+            "version": 2
+        }
+    }
+}
+```
+##### SNMPv3 interface configuration example
+```json
+{
+    "zabbix": {
+        "interface_port": 1610,
+        "interface_type": 2,
+        "snmp": {
+            "authpassphrase": "SecretAuth",
+            "bulk": 1,
+            "securitylevel": 1,
+            "securityname": "MySecurityName",
+            "version": 3
+        }
+    }
+}
+```
+Note: Not all SNMP data is required for a working configuration. [The following parameters are allowed ](https://www.zabbix.com/documentation/current/manual/api/reference/hostinterface/object#details_tag "The following parameters are allowed ")but are not all required, depending on your environment.
+
 #### Permissions
 Make sure that the user has proper permissions for device read and modify (modify to set the Zabbix HostID custom field) operations.