Add a /healthcheck middleware

By default, cinder-api isn't providing a /healthcheck URL, which is
super useful for setting-up monitoring and HAProxy. This patch adds
it by default.

Change-Id: I03a93bf14a5ba159b68bfba15a7f4f26c8200e36

cinder/tests/functional/test_middleware.py

@@ -0,0 +1,33 @@
+# Copyright 2020 Thomas Goirand <zigo@debian.org>
+# Copyright 2020 Infomaniak Networks.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+from oslo_serialization import jsonutils
+import requests
+
+from cinder.tests.functional import functional_helpers
+
+
+class TestHealthCheckMiddleware(functional_helpers._FunctionalTestBase):
+
+    def test_healthcheck(self):
+        # We verify that we return a HTTP200 when calling api_get
+        url = 'http://%s:%s/healthcheck' % (self.osapi.host, self.osapi.port)
+        response = requests.request(
+            'GET',
+            url,
+            headers={'Accept': 'application/json'})
+        output = jsonutils.loads(response.content)
+        self.assertEqual(['OK'], output['reasons'])

etc/cinder/api-paste.ini

@@ -5,6 +5,7 @@
 [composite:osapi_volume]
 use = call:cinder.api:root_app_factory
 /: apiversions
+/healthcheck: healthcheck
 /v2: openstack_volume_api_v2
 /v3: openstack_volume_api_v3
 
@@ -63,3 +64,8 @@ paste.filter_factory = cinder.api.middleware.auth:CinderKeystoneContext.factory
 
 [filter:authtoken]
 paste.filter_factory = keystonemiddleware.auth_token:filter_factory
+
+[app:healthcheck]
+paste.app_factory = oslo_middleware:Healthcheck.app_factory
+backends = disable_by_file
+disable_by_file_path = /etc/cinder/healthcheck_disable

releasenotes/notes/healthcheck-449ed4292e6bfa22.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    The oslo.middleware /healthcheck is now activated by default in the Cinder
+    api-paste.ini. Operators can use it to configure HAproxy or the monitoring
+    of Cinder APIs. Edit the ``api-paste.ini`` file and remove any healthcheck
+    entries to disable this functionality.