Prevent HTML from appearing in API error messages

Currently if the request does not have an Accept header, all pecan
errors end up being HTML, which then gets wrapped into our standard
error format. This change prevents it.

Change-Id: I1968ab20fdeced852744fac5e0e795e997ae6e34
Story: #1662228
Task: #24869

ironic/api/middleware/parsable_error.py

@@ -64,6 +64,11 @@ class ParsableErrorMiddleware(object):
                 state['headers'] = headers
                 return start_response(status, headers, exc_info)
 
+        # The default for ironic is application/json. However, Pecan will try
+        # to output HTML errors if no Accept header is provided.
+        if 'HTTP_ACCEPT' not in environ or environ['HTTP_ACCEPT'] == '*/*':
+            environ['HTTP_ACCEPT'] = 'application/json'
+
         app_iter = self.app(environ, replacement_start_response)
         if (state['status_code'] // 100) not in (2, 3):
             req = webob.Request(environ)

ironic/tests/unit/api/controllers/v1/test_portgroup.py

@@ -400,8 +400,7 @@ class TestListPortgroups(test_api_base.BaseApiTest):
                                  expect_errors=True,
                                  headers={api_base.Version.string: '1.23'})
         self.assertEqual(http_client.NOT_FOUND, response.status_int)
-        self.assertIn('The resource could not be found.',
-                      response.json['error_message'])
+        self.assertIn('Not Found', response.json['error_message'])
 
     def test_ports_subresource_portgroup_not_found(self):
         non_existent_uuid = 'eeeeeeee-cccc-aaaa-bbbb-cccccccccccc'

ironic/tests/unit/api/test_root.py

@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from six.moves import http_client
+
 from ironic.api.controllers.v1 import versions
 from ironic.tests.unit.api import base
 
@@ -35,6 +37,18 @@ class TestRoot(base.BaseApiTest):
                          version1['min_version'])
         self.assertEqual(versions.max_version_string(), version1['version'])
 
+    def test_no_html_errors(self):
+        response = self.get_json('/foo', expect_errors=True)
+        self.assertEqual(http_client.NOT_FOUND, response.status_int)
+        self.assertIn('Not Found', response.json['error_message'])
+        self.assertNotIn('<html', response.json['error_message'])
+
+    def test_no_html_errors2(self):
+        response = self.delete('/v1', expect_errors=True)
+        self.assertEqual(http_client.METHOD_NOT_ALLOWED, response.status_int)
+        self.assertIn('Not Allowed', response.json['error_message'])
+        self.assertNotIn('<html', response.json['error_message'])
+
 
 class TestV1Root(base.BaseApiTest):
 

releasenotes/notes/html-errors-27579342e7e8183b.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    The bare metal API no longer returns HTML as part of the ``error_message``
+    field in error responses when no ``Accept`` header is provided.