Allow overriding envvars as the name of the cloud

For environment variables created cloud objects, it's possible someone
may not want it to be called envvars. I mean, let's be honest, I cannot
imagine why this would be important ... but people get emotional about
things. Let them name their cloud "bunnyrabbit" because that makes
people happy.

Change-Id: I0c232de7d93080ea632fb66a82b9e6d3e925c901

4 files changed, 40 insertions, 17 deletions

diff --git a/README.rst b/README.rst
index 18bf81d..34a1b02 100644
--- a/README.rst
+++ b/README.rst
@@ -18,7 +18,8 @@ provide backwards compatibility to service-specific variables such as
 
 If you have OpenStack environment variables seet and no config files,
 os-client-config will produce a cloud config object named "envvars" containing
-your values from the environment.
+your values from the environment. If you don't like the name "envvars", that's
+ok, you can override it by setting `OS_CLOUD_NAME`.
 
 Service specific settings, like the nova service type, are set with the
 default service type as a prefix. For instance, to set a special service_type
diff --git a/os_client_config/config.py b/os_client_config/config.py
index 70326cf..a0e7672 100644
--- a/os_client_config/config.py
+++ b/os_client_config/config.py
@@ -90,13 +90,24 @@ class OpenStackConfig(object):
             self.cloud_config = dict(
                 clouds=dict(openstack=dict(self.defaults)))
 
+        self.envvar_key = os.environ.pop('OS_CLOUD_NAME', None)
+        if self.envvar_key:
+            if self.envvar_key in self.cloud_config['clouds']:
+                raise exceptions.OpenStackConfigException(
+                    'clouds.yaml defines a cloud named "{0}", but'
+                    ' OS_CLOUD_NAME is also set to "{0}". Please rename'
+                    ' either your environment based cloud, or one of your'
+                    ' file-based clouds.'.format(self.envvar_key))
+        else:
+            self.envvar_key = 'envvars'
+
         envvars = _get_os_environ()
         if envvars:
-            if 'envvars' in self.cloud_config['clouds']:
+            if self.envvar_key in self.cloud_config['clouds']:
                 raise exceptions.OpenStackConfigException(
-                    'clouds.yaml defines a cloud named envvars, and OS_'
+                    'clouds.yaml defines a cloud named {0}, and OS_*'
                     ' env vars are set')
-            self.cloud_config['clouds']['envvars'] = envvars
+            self.cloud_config['clouds'][self.envvar_key] = envvars
 
         self._cache_max_age = None
         self._cache_path = CACHE_PATH
@@ -333,8 +344,8 @@ class OpenStackConfig(object):
         :param kwargs: Additional configuration options
         """
 
-        if cloud is None and 'envvars' in self._get_cloud_sections():
-            cloud = 'envvars'
+        if cloud is None and self.envvar_key in self._get_cloud_sections():
+            cloud = self.envvar_key
 
         args = self._fix_args(kwargs, argparse=argparse)
 
diff --git a/os_client_config/tests/test_config.py b/os_client_config/tests/test_config.py
index 9decf3e..c537842 100644
--- a/os_client_config/tests/test_config.py
+++ b/os_client_config/tests/test_config.py
@@ -14,6 +14,7 @@
 
 from os_client_config import cloud_config
 from os_client_config import config
+from os_client_config import exceptions
 from os_client_config.tests import base
 
 
@@ -36,3 +37,9 @@ class TestConfig(base.TestCase):
         self._assert_cloud_details(cc)
         cc = c.get_one_cloud('_test_cloud_no_vendor')
         self._assert_cloud_details(cc)
+
+    def test_no_environ(self):
+        c = config.OpenStackConfig(config_files=[self.cloud_yaml],
+                                   vendor_files=[self.vendor_yaml])
+        self.assertRaises(
+            exceptions.OpenStackConfigException, c.get_one_cloud, 'envvars')
diff --git a/os_client_config/tests/test_environ.py b/os_client_config/tests/test_environ.py
index 473c417..363cff1 100644
--- a/os_client_config/tests/test_environ.py
+++ b/os_client_config/tests/test_environ.py
@@ -15,32 +15,36 @@
 
 from os_client_config import cloud_config
 from os_client_config import config
-from os_client_config import exceptions
 from os_client_config.tests import base
 
 import fixtures
 
 
-class TestConfig(base.TestCase):
+class TestEnviron(base.TestCase):
+
+    def setUp(self):
+        super(TestEnviron, self).setUp()
+        self.useFixture(
+            fixtures.EnvironmentVariable('OS_AUTH_URL', 'https://example.com'))
+        self.useFixture(
+            fixtures.EnvironmentVariable('OS_USERNAME', 'testuser'))
+        self.useFixture(
+            fixtures.EnvironmentVariable('OS_PROJECT_NAME', 'testproject'))
 
     def test_get_one_cloud(self):
         c = config.OpenStackConfig(config_files=[self.cloud_yaml],
                                    vendor_files=[self.vendor_yaml])
         self.assertIsInstance(c.get_one_cloud(), cloud_config.CloudConfig)
 
-    def test_no_environ(self):
+    def test_envvar_name_override(self):
+        self.useFixture(
+            fixtures.EnvironmentVariable('OS_CLOUD_NAME', 'openstack'))
         c = config.OpenStackConfig(config_files=[self.cloud_yaml],
                                    vendor_files=[self.vendor_yaml])
-        self.assertRaises(
-            exceptions.OpenStackConfigException, c.get_one_cloud, 'envvars')
+        cc = c.get_one_cloud('openstack')
+        self._assert_cloud_details(cc)
 
     def test_environ_exists(self):
-        self.useFixture(
-            fixtures.EnvironmentVariable('OS_AUTH_URL', 'https://example.com'))
-        self.useFixture(
-            fixtures.EnvironmentVariable('OS_USERNAME', 'testuser'))
-        self.useFixture(
-            fixtures.EnvironmentVariable('OS_PROJECT_NAME', 'testproject'))
         c = config.OpenStackConfig(config_files=[self.cloud_yaml],
                                    vendor_files=[self.vendor_yaml])
         cc = c.get_one_cloud('envvars')