Reduce API response times by caching migration flag

awx/main/apps.py

@@ -1,8 +1,17 @@
 from django.apps import AppConfig
+from django.db.models.signals import pre_migrate
 from django.utils.translation import ugettext_lazy as _
 
 
+def raise_migration_flag(**kwargs):
+    from awx.main.tasks import set_migration_flag
+    set_migration_flag.delay()
+
+
 class MainConfig(AppConfig):
 
     name = 'awx.main'
     verbose_name = _('Main')
+
+    def ready(self):
+        pre_migrate.connect(raise_migration_flag, sender=self)

awx/main/middleware.py

@@ -18,6 +18,7 @@ from django.db import IntegrityError, connection
 from django.utils.functional import curry
 from django.shortcuts import get_object_or_404, redirect
 from django.apps import apps
+from django.core.cache import cache
 from django.utils.deprecation import MiddlewareMixin
 from django.utils.translation import ugettext_lazy as _
 from django.urls import reverse, resolve
@@ -213,8 +214,11 @@ class URLModificationMiddleware(MiddlewareMixin):
 class MigrationRanCheckMiddleware(MiddlewareMixin):
 
     def process_request(self, request):
-        executor = MigrationExecutor(connection)
-        plan = executor.migration_plan(executor.loader.graph.leaf_nodes())
-        if bool(plan) and \
-                getattr(resolve(request.path), 'url_name', '') != 'migrations_notran':
-            return redirect(reverse("ui:migrations_notran"))
+        if cache.get('migration_in_progress', False):
+            executor = MigrationExecutor(connection)
+            plan = executor.migration_plan(executor.loader.graph.leaf_nodes())
+            if not bool(plan):
+                logger.info('Detected that migration finished, migration page taken down.')
+                cache.delete('migration_in_progress')
+            elif getattr(resolve(request.path), 'url_name', '') != 'migrations_notran':
+                return redirect(reverse("ui:migrations_notran"))

awx/main/tasks.py

@@ -263,6 +263,12 @@ def apply_cluster_membership_policies():
         logger.debug('Cluster policy computation finished in {} seconds'.format(time.time() - started_compute))
 
 
+@task(queue='tower_broadcast_all', exchange_type='fanout')
+def set_migration_flag():
+    logger.debug('Received migration-in-progress signal, will serve redirect.')
+    cache.set('migration_in_progress', True)
+
+
 @task(queue='tower_broadcast_all', exchange_type='fanout')
 def handle_setting_changes(setting_keys):
     orig_len = len(setting_keys)