Validate local_interface exists

In order to improve the user experiance, we should validate that the
provided local_interface actually exists prior to trying to configure
the undercloud with it. If net_config_override is not used and the
local_interface does not exist, an error will be returned to the
user early on in the installation process. Additionally if the user
does not have an undercloud.conf, a warning is printed to show that
the defaults will be used.

Change-Id: Ia2a7e7fc916f6d2b62e212cb42641494b88d6d17
Closes-Bug: #1709177

instack_undercloud/tests/test_validator.py

@@ -12,6 +12,8 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import mock
+
 from oslo_config import fixture as config_fixture
 from oslotest import base
 
@@ -25,7 +27,9 @@ class TestValidator(base.BaseTestCase):
         self.conf = config_fixture.Config()
         self.useFixture(self.conf)
 
-    def test_validation_passes(self):
+    @mock.patch('netifaces.interfaces')
+    def test_validation_passes(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth1']
         undercloud._validate_network()
 
     def test_fail_on_local_ip(self):
@@ -122,7 +126,9 @@ class TestValidator(base.BaseTestCase):
         validator.validate_config(params, lambda x: None)
         self.assertEqual(save_params, params)
 
-    def test_valid_undercloud_nameserver_passes(self):
+    @mock.patch('netifaces.interfaces')
+    def test_valid_undercloud_nameserver_passes(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth1']
         self.conf.config(undercloud_nameservers=['192.168.24.4',
                                                  '192.168.24.5'])
         undercloud._validate_network()
@@ -144,19 +150,44 @@ class TestValidator(base.BaseTestCase):
         self.assertRaises(validator.FailedValidation,
                           undercloud._validate_network)
 
-    def test_ssl_hosts_allowed(self):
+    @mock.patch('netifaces.interfaces')
+    def test_ssl_hosts_allowed(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth1']
         self.conf.config(undercloud_public_host='public.domain',
                          undercloud_admin_host='admin.domain',
                          undercloud_service_certificate='foo.pem',
                          enable_ui=False)
         undercloud._validate_network()
 
-    def test_allow_all_with_ui(self):
+    @mock.patch('netifaces.interfaces')
+    def test_allow_all_with_ui(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth1']
         self.conf.config(undercloud_admin_host='10.0.0.10',
                          generate_service_certificate=True,
                          enable_ui=True)
 
-    def test_fail_on_invalid_ip(self):
+    @mock.patch('netifaces.interfaces')
+    def test_fail_on_invalid_ip(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth1']
         self.conf.config(dhcp_start='foo.bar')
         self.assertRaises(validator.FailedValidation,
                           undercloud._validate_network)
+
+    @mock.patch('netifaces.interfaces')
+    def test_validate_interface_exists(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth0', 'eth1']
+        self.conf.config(local_interface='eth0')
+        undercloud._validate_network()
+
+    @mock.patch('netifaces.interfaces')
+    def test_fail_validate_interface_missing(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth0', 'eth1']
+        self.conf.config(local_interface='em1')
+        self.assertRaises(validator.FailedValidation,
+                          undercloud._validate_network)
+
+    @mock.patch('netifaces.interfaces')
+    def test_validate_interface_with_net_config_override(self, ifaces_mock):
+        ifaces_mock.return_value = ['eth0', 'eth1']
+        self.conf.config(local_interface='em2', net_config_override='foo')
+        undercloud._validate_network()

instack_undercloud/undercloud.py

@@ -550,6 +550,8 @@ def _load_config():
         conf_params += ['--config-file', PATHS.PASSWORD_PATH]
     if os.path.isfile(PATHS.CONF_PATH):
         conf_params += ['--config-file', PATHS.CONF_PATH]
+    else:
+        LOG.warning('%s does not exist. Using defaults.' % PATHS.CONF_PATH)
     CONF(conf_params)
 
 

instack_undercloud/validator.py

@@ -13,6 +13,7 @@
 # under the License.
 
 import netaddr
+import netifaces
 
 
 class FailedValidation(Exception):
@@ -35,6 +36,7 @@ def validate_config(params, error_callback):
     _validate_inspection_range(local_params, error_callback)
     _validate_no_overlap(local_params, error_callback)
     _validate_ips(local_params, error_callback)
+    _validate_interface_exists(local_params, error_callback)
 
 
 def _validate_ips(params, error_callback):
@@ -143,3 +145,13 @@ def _validate_no_overlap(params, error_callback):
                    (params['inspection_start'], params['inspection_end'],
                     params['dhcp_start'], params['dhcp_end']))
         error_callback(message)
+
+
+def _validate_interface_exists(params, error_callback):
+    """Validate the provided local interface exists"""
+    local_interface = params['local_interface']
+    net_override = params['net_config_override']
+    if not net_override and local_interface not in netifaces.interfaces():
+        message = ('Invalid local_interface specified. %s is not available.' %
+                   local_interface)
+        error_callback(message)

releasenotes/notes/validate-local-interface-faec300f80fadadf.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Validate the local_interface for the undercloud install to fail fast if
+    the interface does not actually exist on the system. If net_config_override
+    is configured, the local_interface will not be validated.
+  - |
+    Log a warning if undercloud.conf is missing to indicate that the defaults
+    will be used.

requirements.txt

@@ -9,6 +9,7 @@ python-swiftclient>=3.2.0 # Apache-2.0
 oslo.config!=4.3.0,!=4.4.0,>=4.0.0 # Apache-2.0
 psutil>=3.2.2 # BSD
 netaddr!=0.7.16,>=0.7.13 # BSD
+netifaces>=0.10.4  # MIT
 pystache # MIT
 os-refresh-config # Apache-2.0
 os-apply-config # Apache-2.0