Use application_url in API version document

This handles the possible vhost in Glance API path correctly
(like https://cloud.example.com/image) contrary to host_url.

Change-Id: If86d805ddc46944e3aa2785aa5d775fe15b8468c
Closes-Bug: #1823703

glance/api/versions.py

@@ -17,6 +17,7 @@ from oslo_config import cfg
 from oslo_log import log as logging
 from oslo_serialization import jsonutils
 from six.moves import http_client
+from six.moves import urllib
 import webob.dec
 
 from glance.common import wsgi
@@ -59,14 +60,17 @@ class Controller(object):
     def index(self, req, explicit=False):
         """Respond to a request for all OpenStack API versions."""
         def build_version_object(version, path, status):
-            url = CONF.public_endpoint or req.host_url
+            url = CONF.public_endpoint or req.application_url
+            # Always add '/' to url end for urljoin href url
+            url = url.rstrip('/') + '/'
+            href = urllib.parse.urljoin(url, path).rstrip('/') + '/'
             return {
                 'id': 'v%s' % version,
                 'status': status,
                 'links': [
                     {
                         'rel': 'self',
-                        'href': '%s/%s/' % (url, path),
+                        'href': '%s' % href,
                     },
                 ],
             }

glance/tests/unit/test_versions.py

@@ -135,6 +135,17 @@ class VersionsTest(base.IsolatedUnitTest):
         expected = self._get_versions_list(ssl_url)
         self.assertEqual(expected, results)
 
+    def test_get_version_list_for_external_app(self):
+        url = 'http://customhost:9292/app/api'
+        req = webob.Request.blank('/', base_url=url)
+        self.config(bind_host='127.0.0.1', bind_port=9292)
+        res = versions.Controller().index(req)
+        self.assertEqual(http.MULTIPLE_CHOICES, res.status_int)
+        self.assertEqual('application/json', res.content_type)
+        results = jsonutils.loads(res.body)['versions']
+        expected = self._get_versions_list(url)
+        self.assertEqual(expected, results)
+
 
 class VersionNegotiationTest(base.IsolatedUnitTest):