multitenant: skip tenants where all migrations are applied (#29522)

hobo/multitenant/management/commands/migrate_schemas.py

@@ -1,7 +1,9 @@
 import django
 from optparse import NO_DEFAULT
 
+from django.apps import apps
 from django.core.management.commands.migrate import Command as MigrateCommand
+from django.db.migrations.loader import MigrationLoader
 from django.db.migrations.recorder import MigrationRecorder
 from django.db import connection
 from django.conf import settings
@@ -45,9 +47,39 @@ class MigrateSchemasCommand(SyncCommon):
                 else:
                     self.run_migrations(self.schema_name, settings.TENANT_APPS)
             else:
+                app_labels = []
+                for app in apps.get_app_configs():
+                    if app.name in settings.TENANT_APPS:
+                        app_labels.append(app.label)
+                loader = MigrationLoader(connection)
+                loader.load_disk()
+                recorder = MigrationRecorder(connection)
+                applied_public_migrations = set(
+                        [(app, migration) for app, migration
+                         in recorder.applied_migrations()
+                         if app in app_labels and
+                            (app, migration) in loader.disk_migrations])
                 for tenant in TenantMiddleware.get_tenants():
+                    connection.set_schema(tenant.schema_name, include_public=False)
+                    applied_migrations = self.get_applied_migrations(app_labels)
+                    if options.get('fake'):
+                        # disregard applied migrations if --fake is given.
+                        applied_migrations = []
+                    if all([x in applied_migrations for x in applied_public_migrations]):
+                        if int(self.options.get('verbosity', 1)) >= 1:
+                            self._notice("=== Skipping migrations of schema %s" % tenant.schema_name)
+                        continue
                     self.run_migrations(tenant.schema_name, settings.TENANT_APPS)
 
+    def get_applied_migrations(self, app_labels):
+        applied_migrations = []
+        with connection.cursor() as cursor:
+            cursor.execute('SELECT app, name FROM django_migrations')
+            for row in cursor.fetchall():
+                applied_migrations.append(row)
+        applied_migrations = [x for x in applied_migrations if x[0] in app_labels]
+        return applied_migrations
+
     def run_migrations(self, schema_name, included_apps):
         if int(self.options.get('verbosity', 1)) >= 1:
             self._notice("=== Running migrate for schema %s" % schema_name)