Allow passing of version header

Add keyword option to get_version_data() to allow passing
of the version header so that we can get the microversions.
Specifically, this is so that we can re-use this function
in barbican, which recently implemented microversions, but
doesn't return them by default, for backward compatibility
with old clients.

Change-Id: I909750381a559f9dc61650c9f98c88d4481012b7

keystoneauth1/discover.py

@@ -58,7 +58,7 @@ def _int_or_latest(val):
     return LATEST if val == 'latest' or val == LATEST else int(val)
 
 
-def get_version_data(session, url, authenticated=None):
+def get_version_data(session, url, authenticated=None, version_header=None):
     """Retrieve raw version data from a url.
 
     The return is a list of dicts of the form::
@@ -93,10 +93,15 @@ def get_version_data(session, url, authenticated=None):
     :param string url: Endpoint or discovery URL from which to retrieve data.
     :param bool authenticated: Include a token in the discovery call.
                                (optional) Defaults to None.
+    :param string version_header: provide the OpenStack-API-Version header
+        for services which don't return version information without it, for
+        backward compatibility.
     :return: A list of dicts containing version information.
     :rtype: list(dict)
     """
     headers = {'Accept': 'application/json'}
+    if version_header:
+        headers['OpenStack-API-Version'] = version_header
 
     try:
         resp = session.get(url, headers=headers, authenticated=authenticated)

keystoneauth1/tests/unit/test_discovery.py

@@ -1321,7 +1321,8 @@ class EndpointDataTests(utils.TestCase):
 
     def test_run_discovery_auth(self):
         url = 'https://example.com'
-        headers = {'Accept': 'application/json'}
+        headers = {'Accept': 'application/json',
+                   'OpenStack-API-Version': 'version header test'}
 
         session = mock.Mock()
         session.get.side_effect = [
@@ -1332,7 +1333,8 @@ class EndpointDataTests(utils.TestCase):
         ]
 
         try:
-            discover.get_version_data(session, url)
+            discover.get_version_data(
+                session, url, version_header='version header test')
         except exceptions.BadRequest:
             pass
         # Only one call with 'url'