[APIImpact] Correct API response code for DELETE cache APIs

DELETE /v2/cache/{image_id} and /v2/cache returns HTTP 200 response
code to user but as per proposal it should be HTTP 204. This change
returns HTTP 204 response to user.

Closes-Bug: #1980049
Change-Id: I9d1c25638584fe346e3937d0536413d548d46e8e

glance/api/v2/cached_images.py

@@ -240,6 +240,12 @@ class CachedImageSerializer(wsgi.JSONResponseSerializer):
     def queue_image_from_api(self, response, result):
         response.status_int = 202
 
+    def clear_cache(self, response, result):
+        response.status_int = 204
+
+    def delete_cache_entry(self, response, result):
+        response.status_int = 204
+
 
 def create_resource():
     """Cached Images resource factory method"""

glance/tests/functional/v2/test_cache_api.py

@@ -85,12 +85,12 @@ class TestImageCache(functional.SynchronousAPIBase):
         response = self.api_put(path)
         self.assertEqual(expected_code, response.status_code)
 
-    def cache_delete(self, image_id, expected_code=200):
+    def cache_delete(self, image_id, expected_code=204):
         path = '/v2/cache/%s' % image_id
         response = self.api_delete(path)
         self.assertEqual(expected_code, response.status_code)
 
-    def cache_clear(self, target='', expected_code=200):
+    def cache_clear(self, target='', expected_code=204):
         path = '/v2/cache'
         headers = {}
         if target:

releasenotes/notes/bug-1980049-623d2eb0fa074136.yaml

@@ -0,0 +1,14 @@
+---
+upgrade:
+  - |
+    The Image service API call ``DELETE /v2/cache/{image_id}`` and
+    ``DELETE /v2/cache`` now returns a 204 (No Content) response code
+    to indicate success. In glance 24.0.0 (the initial Yoga release),
+    it had mistakenly returned a 200.
+
+fixes:
+  - |
+    Bug `1980049 <https://bugs.launchpad.net/glance/+bug/1980049>`_:
+    Fixed the success response code of the REST API call
+    ``DELETE /v2/cache/{image_id}`` and ``DELETE /v2/cache`` to be
+    204 (No Content), following the original design of the feature.