Closes #84: Introduce the max_active_branches parameter

docs/configuration.md

@@ -1,10 +1,18 @@
 # Configuration Parameters
 
+## `max_active_branches`
+
+Default: None
+
+The maximum number of _active_ branches that can exist simultaneously. This count excludes branches which have been merged or archived.
+
+---
+
 ## `max_branches`
 
 Default: None
 
-The maximum number of branches that can exist simultaneously, including merged branches that have not been deleted. It may be desirable to limit the total number of provisioned branches to safeguard against excessive database size.
+The maximum total number of branches that can exist simultaneously, including merged branches that have not been deleted. It may be desirable to limit the total number of provisioned branches to safeguard against excessive database size.
 
 ---
 

netbox_branching/__init__.py

@@ -16,6 +16,9 @@ class AppConfig(PluginConfig):
         'netbox_branching.middleware.BranchMiddleware'
     ]
     default_settings = {
+        # The maximum number of active branches (excludes merged & archived branches)
+        'max_active_branches': None,
+
         # The maximum number of branches which can be provisioned simultaneously
         'max_branches': None,
 

netbox_branching/choices.py

@@ -28,7 +28,13 @@ class BranchStatusChoices(ChoiceSet):
         PROVISIONING,
         SYNCING,
         MERGING,
-        REVERTING
+        REVERTING,
+    )
+
+    ACTIVE_STATUSES = (
+        NEW,
+        READY,
+        *TRANSITIONAL,
     )
 
 

netbox_branching/models/branches.py

@@ -127,17 +127,28 @@ def synced_time(self):
 
     def clean(self):
 
-        # Check whether we're exceeding the maximum number of Branches
+        # Enforce the maximum number of total branches
         if not self.pk and (max_branches := get_plugin_config('netbox_branching', 'max_branches')):
-            branch_count = Branch.objects.count()
-            if branch_count >= max_branches:
+            total_branch_count = Branch.objects.count()
+            if total_branch_count >= max_branches:
                 raise ValidationError(
                     _(
                         "The configured maximum number of branches ({max}) cannot be exceeded. One or more existing "
                         "branches must be deleted before a new branch may be created."
                     ).format(max=max_branches)
                 )
 
+        # Enforce the maximum number of active branches
+        if not self.pk and (max_active_branches := get_plugin_config('netbox_branching', 'max_active_branches')):
+            active_branch_count = Branch.objects.filter(status__in=BranchStatusChoices.ACTIVE_STATUSES).count()
+            if active_branch_count >= max_active_branches:
+                raise ValidationError(
+                    _(
+                        "The configured maximum number of active branches ({max}) cannot be exceeded. One or more "
+                        "active branches must be archived or deleted before a new branch may be created."
+                    ).format(max=max_active_branches)
+                )
+
     def save(self, provision=True, *args, **kwargs):
         """
         Args:

netbox_branching/tests/test_branches.py

@@ -4,6 +4,7 @@
 from django.db import connection
 from django.test import TransactionTestCase, override_settings
 
+from netbox_branching.choices import BranchStatusChoices
 from netbox_branching.constants import MAIN_SCHEMA
 from netbox_branching.models import Branch
 from netbox_branching.utilities import get_tables_to_replicate
@@ -77,6 +78,30 @@ def test_branch_schema_id(self):
         branch.refresh_from_db()
         self.assertEqual(branch.schema_id, schema_id, msg="Schema ID was changed during save()")
 
+    @override_settings(PLUGINS_CONFIG={
+        'netbox_branching': {
+            'max_active_branches': 2,
+        }
+    })
+    def test_max_active_branches(self):
+        """
+        Verify that the max_active_branches config parameter is enforced.
+        """
+        Branch.objects.bulk_create((
+            Branch(name='Branch 1', status=BranchStatusChoices.MERGED),
+            Branch(name='Branch 2', status=BranchStatusChoices.READY),
+        ))
+
+        # Second active branch should be permitted (merged branches don't count)
+        branch = Branch(name='Branch 3')
+        branch.full_clean()
+        branch.save()
+
+        # Attempting to create a third active branch should fail
+        branch = Branch(name='Branch 4')
+        with self.assertRaises(ValidationError):
+            branch.full_clean()
+
     @override_settings(PLUGINS_CONFIG={
         'netbox_branching': {
             'max_branches': 2,