Support passing force_ipv4 to the constructor

IPv6 support is detectable, so rather than having a user opt-in to it,
provide a flag that can be provided to tell it that detected IPv6
support is lying. This should have to be set for far fewer people and
should result in transparent opt-in to IPv6 where available.

Change-Id: Ib0c4c4e8b3b7b4bcee5fa3414719969274929b9a

6 files changed, 64 insertions, 26 deletions

diff --git a/README.rst b/README.rst
index 488dd24..21532eb 100644
--- a/README.rst
+++ b/README.rst
@@ -197,15 +197,18 @@ are connecting to OpenStack can share a cache should you desire.
 IPv6
 ----
 
-IPv6 may be a thing you would prefer to use not only if the cloud supports it,
-but also if your local machine support it. A simple boolean flag is settable
-either in an environment variable, `OS_PREFER_IPV6`, or in the client section
-of the clouds.yaml.
+IPv6 is the future, and you should always use if if your cloud supports it and
+if your local network supports it. Both of those are eaily detectable and all
+friendly software should do the right thing. However, sometimes you might
+exist in a location where you have an IPv6 stack, but something evil has
+caused it to not actually function. In that case, there is a config option
+you can set to unbreak you `force_ipv4`, or `OS_FORCE_IPV4` boolean
+environment variable.
 
 ::
 
   client:
-    prefer_ipv6: true
+    force_ipv4: true
   clouds:
     mordred:
       profile: hp
@@ -222,9 +225,8 @@ of the clouds.yaml.
         project_name: mordred@inaugust.com
       region_name: DFW
 
-The above snippet will tell client programs to prefer returning an IPv6
-address. This will result in calls to, for instance, `shade`'s `get_public_ip`
-to return an IPv4 address on HP, and an IPv6 address on Rackspace.
+The above snippet will tell client programs to prefer returning an IPv4
+address.
 
 Usage
 -----
diff --git a/os_client_config/cloud_config.py b/os_client_config/cloud_config.py
index 86b4f50..c8b5269 100644
--- a/os_client_config/cloud_config.py
+++ b/os_client_config/cloud_config.py
@@ -17,11 +17,11 @@ import warnings
 
 class CloudConfig(object):
     def __init__(self, name, region, config,
-                 prefer_ipv6=False, auth_plugin=None):
+                 force_ipv4=False, auth_plugin=None):
         self.name = name
         self.region = region
         self.config = config
-        self._prefer_ipv6 = prefer_ipv6
+        self._force_ipv4 = force_ipv4
         self._auth = auth_plugin
 
     def __getattr__(self, key):
@@ -107,7 +107,11 @@ class CloudConfig(object):
 
     @property
     def prefer_ipv6(self):
-        return self._prefer_ipv6
+        return not self._force_ipv4
+
+    @property
+    def force_ipv4(self):
+        return self._force_ipv4
 
     def get_auth(self):
         """Return a keystoneauth plugin from the auth credentials."""
diff --git a/os_client_config/config.py b/os_client_config/config.py
index 2cea7ee..f43fe74 100644
--- a/os_client_config/config.py
+++ b/os_client_config/config.py
@@ -113,7 +113,7 @@ def _auth_update(old_dict, new_dict):
 class OpenStackConfig(object):
 
     def __init__(self, config_files=None, vendor_files=None,
-                 override_defaults=None):
+                 override_defaults=None, force_ipv4=None):
         self._config_files = config_files or CONFIG_FILES
         self._vendor_files = vendor_files or VENDOR_FILES
 
@@ -135,11 +135,28 @@ class OpenStackConfig(object):
 
         # Grab ipv6 preference settings from env
         client_config = self.cloud_config.get('client', {})
-        self.prefer_ipv6 = get_boolean(
-            os.environ.pop(
-                'OS_PREFER_IPV6', client_config.get(
-                    'prefer_ipv6', client_config.get(
-                        'prefer-ipv6', False))))
+
+        if force_ipv4 is not None:
+            # If it's passed in to the constructor, honor it.
+            self.force_ipv4 = force_ipv4
+        else:
+            # Get the backwards compat value
+            prefer_ipv6 = get_boolean(
+                os.environ.pop(
+                    'OS_PREFER_IPV6', client_config.get(
+                        'prefer_ipv6', client_config.get(
+                            'prefer-ipv6', True))))
+            force_ipv4 = get_boolean(
+                os.environ.pop(
+                    'OS_FORCE_IPV4', client_config.get(
+                        'force_ipv4', client_config.get(
+                            'broken-ipv6', False))))
+
+            self.force_ipv4 = force_ipv4
+            if not prefer_ipv6:
+                # this will only be false if someone set it explicitly
+                # honor their wishes
+                self.force_ipv4 = True
 
         # Next, process environment variables and add them to the mix
         self.envvar_key = os.environ.pop('OS_CLOUD_NAME', 'envvars')
@@ -586,7 +603,10 @@ class OpenStackConfig(object):
             if hasattr(value, 'format'):
                 config[key] = value.format(**config)
 
-        prefer_ipv6 = config.pop('prefer_ipv6', self.prefer_ipv6)
+        force_ipv4 = config.pop('force_ipv4', self.force_ipv4)
+        prefer_ipv6 = config.pop('prefer_ipv6', True)
+        if not prefer_ipv6:
+            force_ipv4 = True
 
         if cloud is None:
             cloud_name = ''
@@ -595,7 +615,7 @@ class OpenStackConfig(object):
         return cloud_config.CloudConfig(
             name=cloud_name, region=config['region_name'],
             config=self._normalize_keys(config),
-            prefer_ipv6=prefer_ipv6,
+            force_ipv4=force_ipv4,
             auth_plugin=auth_plugin)
 
     @staticmethod
diff --git a/os_client_config/tests/base.py b/os_client_config/tests/base.py
index cbf58da..36c3bfb 100644
--- a/os_client_config/tests/base.py
+++ b/os_client_config/tests/base.py
@@ -40,7 +40,7 @@ VENDOR_CONF = {
 }
 USER_CONF = {
     'client': {
-        'prefer_ipv6': True,
+        'force_ipv4': True,
     },
     'clouds': {
         '_test-cloud_': {
diff --git a/os_client_config/tests/test_cloud_config.py b/os_client_config/tests/test_cloud_config.py
index 4f5260f..c9317ad 100644
--- a/os_client_config/tests/test_cloud_config.py
+++ b/os_client_config/tests/test_cloud_config.py
@@ -50,7 +50,7 @@ class TestCloudConfig(base.TestCase):
         self.assertIsNone(cc.x)
 
         # Test default ipv6
-        self.assertFalse(cc.prefer_ipv6)
+        self.assertFalse(cc.force_ipv4)
 
     def test_iteration(self):
         cc = cloud_config.CloudConfig("test1", "region-al", fake_config_dict)
@@ -116,8 +116,8 @@ class TestCloudConfig(base.TestCase):
 
     def test_ipv6(self):
         cc = cloud_config.CloudConfig(
-            "test1", "region-al", fake_config_dict, prefer_ipv6=True)
-        self.assertTrue(cc.prefer_ipv6)
+            "test1", "region-al", fake_config_dict, force_ipv4=True)
+        self.assertTrue(cc.force_ipv4)
 
     def test_getters(self):
         cc = cloud_config.CloudConfig("test1", "region-al", fake_services_dict)
diff --git a/os_client_config/tests/test_config.py b/os_client_config/tests/test_config.py
index 3331b33..271c40b 100644
--- a/os_client_config/tests/test_config.py
+++ b/os_client_config/tests/test_config.py
@@ -136,16 +136,28 @@ class TestConfig(base.TestCase):
         c.get_one_cloud(cloud='defaults', validate=False)
 
     def test_prefer_ipv6_true(self):
+        c = config.OpenStackConfig(config_files=[self.no_yaml],
+                                   vendor_files=[self.no_yaml])
+        cc = c.get_one_cloud(cloud='defaults', validate=False)
+        self.assertTrue(cc.prefer_ipv6)
+
+    def test_prefer_ipv6_false(self):
         c = config.OpenStackConfig(config_files=[self.cloud_yaml],
                                    vendor_files=[self.vendor_yaml])
         cc = c.get_one_cloud(cloud='_test-cloud_')
-        self.assertTrue(cc.prefer_ipv6)
+        self.assertFalse(cc.prefer_ipv6)
 
-    def test_prefer_ipv6_false(self):
+    def test_force_ipv4_true(self):
+        c = config.OpenStackConfig(config_files=[self.cloud_yaml],
+                                   vendor_files=[self.vendor_yaml])
+        cc = c.get_one_cloud(cloud='_test-cloud_')
+        self.assertTrue(cc.force_ipv4)
+
+    def test_force_ipv4_false(self):
         c = config.OpenStackConfig(config_files=[self.no_yaml],
                                    vendor_files=[self.no_yaml])
         cc = c.get_one_cloud(cloud='defaults', validate=False)
-        self.assertFalse(cc.prefer_ipv6)
+        self.assertFalse(cc.force_ipv4)
 
     def test_get_one_cloud_auth_merge(self):
         c = config.OpenStackConfig(config_files=[self.cloud_yaml])