Add function to load YAML files

This commit starts to remove some code redundancy from the startup
scripts for easier maintenance.

startup_scripts/160_aggregates.py

@@ -1,46 +1,42 @@
 from ipam.models import Aggregate, RIR
-from ruamel.yaml import YAML
+
 from extras.models import CustomField, CustomFieldValue
 
 from netaddr import IPNetwork
-from pathlib import Path
+from startup_script_utils import load_yaml
 import sys
 
-file = Path('/opt/netbox/initializers/aggregates.yml')
-if not file.is_file():
+aggregates = load_yaml('/opt/netbox/initializers/aggregates.yml')
+
+if aggregates is None:
   sys.exit()
 
-with file.open('r') as stream:
-  yaml = YAML(typ='safe')
-  aggregates = yaml.load(stream)
+required_assocs = {
+  'rir': (RIR, 'name')
+}
 
-  required_assocs = {
-    'rir': (RIR, 'name')
-  }
+for params in aggregates:
+  custom_fields = params.pop('custom_fields', None)
+  params['prefix'] = IPNetwork(params['prefix'])
 
-  if aggregates is not None:
-    for params in aggregates:
-      custom_fields = params.pop('custom_fields', None)
-      params['prefix'] = IPNetwork(params['prefix'])
+  for assoc, details in required_assocs.items():
+    model, field = details
+    query = { field: params.pop(assoc) }
 
-      for assoc, details in required_assocs.items():
-        model, field = details
-        query = { field: params.pop(assoc) }
+    params[assoc] = model.objects.get(**query)
 
-        params[assoc] = model.objects.get(**query)
+  aggregate, created = Aggregate.objects.get_or_create(**params)
 
-      aggregate, created = Aggregate.objects.get_or_create(**params)
+  if created:
+    if custom_fields is not None:
+      for cf_name, cf_value in custom_fields.items():
+        custom_field = CustomField.objects.get(name=cf_name)
+        custom_field_value = CustomFieldValue.objects.create(
+          field=custom_field,
+          obj=aggregate,
+          value=cf_value
+        )
 
-      if created:
-        if custom_fields is not None:
-          for cf_name, cf_value in custom_fields.items():
-            custom_field = CustomField.objects.get(name=cf_name)
-            custom_field_value = CustomFieldValue.objects.create(
-              field=custom_field,
-              obj=aggregate,
-              value=cf_value
-            )
+        aggregate.custom_field_values.add(custom_field_value)
 
-            aggregate.custom_field_values.add(custom_field_value)
-
-        print("🗞️ Created Aggregate", aggregate.prefix)
+    print("🗞️ Created Aggregate", aggregate.prefix)