Merge "Specify the config file with environment variable"

README.rst

@@ -43,6 +43,10 @@ locations:
 
 The first file found wins.
 
+You can also set the environment variable `OS_CLIENT_CONFIG_FILE` to an
+absolute path of a file to look for and that location will be inserted at the
+front of the file search list.
+
 The keys are all of the keys you'd expect from `OS_*` - except lower case
 and without the OS prefix. So, region name is set with `region_name`.
 

os_client_config/config.py

@@ -106,6 +106,10 @@ class OpenStackConfig(object):
         self._config_files = config_files or CONFIG_FILES
         self._vendor_files = vendor_files or VENDOR_FILES
 
+        config_file_override = os.environ.pop('OS_CLIENT_CONFIG_FILE', None)
+        if config_file_override:
+            self._config_files.insert(0, config_file_override)
+
         self.defaults = defaults.get_defaults()
         if override_defaults:
             self.defaults.update(override_defaults)

os_client_config/tests/test_environ.py

@@ -84,3 +84,12 @@ class TestEnviron(base.TestCase):
         self._assert_cloud_details(cc)
         cc = c.get_one_cloud('_test_cloud_no_vendor')
         self._assert_cloud_details(cc)
+
+    def test_config_file_override(self):
+        self.useFixture(
+            fixtures.EnvironmentVariable(
+                'OS_CLIENT_CONFIG_FILE', self.cloud_yaml))
+        c = config.OpenStackConfig(config_files=[],
+                                   vendor_files=[self.vendor_yaml])
+        cc = c.get_one_cloud('_test-cloud_')
+        self._assert_cloud_details(cc)