alpine: support non-VM hosts in interfaces template

Ignore OOB management interface, allow configuring loopback interface
with NetBox data, and setting MTU.

filter_plugins/util.py

@@ -0,0 +1,21 @@
+#!/usr/bin/python
+
+class FilterModule(object):
+    '''Helper filters to make Ansible less unpleasant'''
+    def filters(self):
+        return {
+            'defaultattr': self.defaultattr,
+            'list2dict': self.list2dict,
+        }
+
+    def defaultattr(self, objects, attr, val=None):
+        '''
+        Set a default value if the given attribute is not defined for an object.
+        '''
+        yield from (obj | { attr: obj.get(attr, val) } for obj in objects)
+
+    def list2dict(self, items, key):
+        '''
+        Like items2dict but keep entire dictionaries as values.
+        '''
+        return {item[key]: item for item in items}