Include swap in memory check

It's not uncommon for developers to use SSD-backed swap to allow
for more instances on a limited memory baremetal system.  Previously
this was not allowed by the memory check because it only looked at
physical memory.  This change includes swap in the memory check so
that use case is supported out of the box.

Change-Id: If7fdf189fadd39cd6380c15a35f4b7d49cc42a96

instack_undercloud/tests/test_undercloud.py

@@ -240,18 +240,33 @@ class TestCheckHostname(BaseTestCase):
 
 
 class TestCheckMemory(BaseTestCase):
+    @mock.patch('psutil.swap_memory')
     @mock.patch('psutil.virtual_memory')
-    def test_sufficient_memory(self, mock_vm):
+    def test_sufficient_memory(self, mock_vm, mock_sm):
         mock_vm.return_value = mock.Mock()
         mock_vm.return_value.total = 8589934592
+        mock_sm.return_value = mock.Mock()
+        mock_sm.return_value.total = 0
         undercloud._check_memory()
 
+    @mock.patch('psutil.swap_memory')
     @mock.patch('psutil.virtual_memory')
-    def test_insufficient_memory(self, mock_vm):
+    def test_insufficient_memory(self, mock_vm, mock_sm):
         mock_vm.return_value = mock.Mock()
         mock_vm.return_value.total = 2071963648
+        mock_sm.return_value = mock.Mock()
+        mock_sm.return_value.total = 0
         self.assertRaises(RuntimeError, undercloud._check_memory)
 
+    @mock.patch('psutil.swap_memory')
+    @mock.patch('psutil.virtual_memory')
+    def test_sufficient_swap(self, mock_vm, mock_sm):
+        mock_vm.return_value = mock.Mock()
+        mock_vm.return_value.total = 6442450944
+        mock_sm.return_value = mock.Mock()
+        mock_sm.return_value.total = 2147483648
+        undercloud._check_memory()
+
 
 class TestCheckSysctl(BaseTestCase):
     @mock.patch('os.path.isfile')

instack_undercloud/undercloud.py

@@ -607,7 +607,8 @@ def _check_memory():
     proceeding with install.
     """
     mem = psutil.virtual_memory()
-    total_mb = mem.total / 1024 / 1024
+    swap = psutil.swap_memory()
+    total_mb = (mem.total + swap.total) / 1024 / 1024
     if total_mb < REQUIRED_MB:
         LOG.error('At least %d MB of memory is required for undercloud '
                   'installation.  A minimum of 8 GB is recommended. '

releasenotes/notes/include-swap-in-memory-check-fe378284f06aae1a.yaml

@@ -0,0 +1,7 @@
+---
+other:
+  - |
+    Swap memory is now included in the minimum memory check.  While relying on
+    swap is still not recommended for production deployments, it is not
+    uncommon for developers to use SSD-backed swap to fit more instances into
+    a system with limited memory.