Add check for sufficient memory to undercloud install

It turns out that it is possible to install the undercloud on a
2 GB system, but it will cause all kinds of weird problems and not
perform well.  Let's be explicit about our requirements and refuse
to install in such an environment.

Change-Id: I7aae41b57cb82e1d776b200ff56fd90756eff19e

instack_undercloud/tests/test_undercloud.py

@@ -40,6 +40,7 @@ class BaseTestCase(base.BaseTestCase):
 class TestUndercloud(BaseTestCase):
     @mock.patch('instack_undercloud.undercloud._configure_logging')
     @mock.patch('instack_undercloud.undercloud._check_hostname')
+    @mock.patch('instack_undercloud.undercloud._check_memory')
     @mock.patch('instack_undercloud.undercloud._run_command')
     @mock.patch('instack_undercloud.undercloud._post_config')
     @mock.patch('instack_undercloud.undercloud._run_orc')
@@ -48,11 +49,13 @@ class TestUndercloud(BaseTestCase):
     @mock.patch('instack_undercloud.undercloud._load_config')
     def test_install(self, mock_load_config, mock_generate_environment,
                      mock_run_instack, mock_run_orc, mock_post_config,
-                     mock_run_command, mock_check_hostname,
+                     mock_run_command, mock_check_memory, mock_check_hostname,
                      mock_configure_logging):
         fake_env = mock.MagicMock()
         mock_generate_environment.return_value = fake_env
         undercloud.install('.')
+        self.assertEqual(True, mock_check_hostname.called)
+        self.assertEqual(True, mock_check_memory.called)
         mock_generate_environment.assert_called_with('.')
         mock_run_instack.assert_called_with(fake_env)
         mock_run_orc.assert_called_with(fake_env)
@@ -127,6 +130,20 @@ class TestCheckHostname(BaseTestCase):
             self.assertRaises(RuntimeError, undercloud._check_hostname)
 
 
+class TestCheckMemory(BaseTestCase):
+    @mock.patch('psutil.virtual_memory')
+    def test_sufficient_memory(self, mock_vm):
+        mock_vm.return_value = mock.Mock()
+        mock_vm.return_value.total = 4143927296
+        undercloud._check_memory()
+
+    @mock.patch('psutil.virtual_memory')
+    def test_insufficient_memory(self, mock_vm):
+        mock_vm.return_value = mock.Mock()
+        mock_vm.return_value.total = 2071963648
+        self.assertRaises(RuntimeError, undercloud._check_memory)
+
+
 class TestGenerateEnvironment(BaseTestCase):
     def setUp(self):
         super(TestGenerateEnvironment, self).setUp()

instack_undercloud/undercloud.py

@@ -27,6 +27,7 @@ import uuid
 from novaclient import client as novaclient
 from novaclient import exceptions
 from oslo_config import cfg
+import psutil
 import six
 from six.moves import configparser
 
@@ -71,6 +72,9 @@ secured.
 
 #############################################################################
 """
+# We need 4 GB, leave a little room for variation in what 4 GB means on
+# different platforms.
+REQUIRED_MB = 3750
 
 
 # When adding new options to the lists below, make sure to regenerate the
@@ -362,6 +366,22 @@ def _check_hostname():
             raise RuntimeError('Static hostname not set in /etc/hosts')
 
 
+def _check_memory():
+    """Check system memory
+
+    The undercloud will not run properly in less than 4 GB of memory.
+    This function verifies that at least that much is available before
+    proceeding with install.
+    """
+    mem = psutil.virtual_memory()
+    total_mb = mem.total / 1024 / 1024
+    if total_mb < REQUIRED_MB:
+        LOG.error('At least 4 GB of memory is required for undercloud '
+                  'installation.  A minimum of 6 GB is recommended. '
+                  'Only detected %d MB' % total_mb)
+        raise RuntimeError('Insufficient memory available')
+
+
 def _generate_password(length=40):
     """Create a random password
 
@@ -595,6 +615,7 @@ def install(instack_root):
     LOG.info('Logging to %s', PATHS.LOG_FILE)
     _load_config()
     _check_hostname()
+    _check_memory()
     instack_env = _generate_environment(instack_root)
     _run_instack(instack_env)
     # NOTE(bnemec): I removed the conditional running of os-refresh-config.

requirements.txt

@@ -1,3 +1,4 @@
 six>=1.9.0
 python-novaclient
 oslo.config
+psutil>=1.1.1,<2.0.0