Find correct listener for WSGI based monasca-api

With this commit in place, monasca-api will find the correct
listener process for monasca-api rather than one of the WSGI
workers.

Change-Id: Id6356bbfee9c3069d9232d990b20174b2fb67ba7
Story: 1674406
Task: 3952

monasca_setup/detection/plugins/mon.py

@@ -21,10 +21,15 @@ from monasca_setup.detection.utils import watch_process_by_username
 
 log = logging.getLogger(__name__)
 
-_PYTHON_LANG_MARKERS = 'python', 'gunicorn', 'httpd', 'apache',
+_APACHE_MARKERS = 'httpd', 'apache',
+"""List of all strings in process command line that indicate application
+runs in Apache/mod_wsgi"""
+_PYTHON_LANG_MARKERS = ('python', 'gunicorn') + _APACHE_MARKERS
 """List of all strings that if found in process exe
 mean that application runs under Python"""
 _JAVA_LANG_MARKERS = 'java',
+"""List of all strings that if found in process exe
+mean that application runs under Java"""
 
 _DEFAULT_API_PORT = 8070
 """Default TCP port which monasca-api process should be available by"""
@@ -91,11 +96,36 @@ class MonAPI(monasca_setup.detection.Plugin):
                     return True
             return False
 
+        def correct_apache_listener(process):
+            """Sets api_process to the parent httpd process.
+
+            Method evaluates if process executable is correlated
+            with apache-mod_wsgi. If so, retrieves parent process.
+            Otherwise returns None
+
+            :param process: current process
+            :type process: psutil.Process
+            :returns: parent process or None
+            :rtype: (psutil.Process, None)
+
+            """
+
+            p_exe = process.as_dict()['exe']
+            for m in _APACHE_MARKERS:
+                if m in p_exe:
+                    return process.parent()
+            return None
+
         api_process = find_process_cmdline('monasca-api')
         process_found = api_process is not None
 
         if process_found:
             impl_lang = _get_impl_lang(api_process)
+            if impl_lang == 'python':
+                apache_process = correct_apache_listener(api_process)
+                if apache_process:
+                    log.info('\tmonasca-api runs under Apache WSGI')
+                    api_process = apache_process
             impl_helper = self._init_impl_helper(impl_lang)
 
             impl_helper.load_configuration()

tests/detection/test_mon.py

@@ -102,6 +102,15 @@ class FakeProcesses(object):
         return FakeProcesses.inetConnections
 
 
+class FakeWSGIWorkers(FakeProcesses):
+    def __init__(self, cmdline=None):
+        self.cmdLine = cmdline
+    def parent(self):
+        return FakeProcesses()
+    def connections(self, *args):
+        return []
+
+
 class TestGetImplLang(unittest.TestCase):
     @mock.patch('psutil.Process')
     def test_should_return_python_lang_for_gunicorn_process(self, proc):
@@ -330,12 +339,10 @@ class TestMonAPIDetectionPlugin(unittest.TestCase):
 
     @mock.patch('monasca_setup.detection.plugins.mon._MonAPIPythonHelper')
     def test_should_use_python_helper_if_api_is_wsgi(self, impl_helper):
-        FakeProcesses.cmdLine = [_PYTHON_WSGI_CMD_API]
-
         self._mon_api._init_impl_helper = iih = mock.Mock(
             return_value=impl_helper)
 
-        self._detect()
+        self._detect([FakeWSGIWorkers([_PYTHON_WSGI_CMD_API])])
 
         iih.assert_called_once_with('python')
         self.assertTrue(impl_helper.load_configuration.called_once)
@@ -543,12 +550,11 @@ class TestMonAPIDetectionPlugin(unittest.TestCase):
         self.assertNotEqual({}, conf)
         return conf
 
-    def _detect(self):
+    def _detect(self, retval=[FakeProcesses()]):
         self._mon_api.available = False
 
         process_iter = mock.patch.object(psutil, 'process_iter',
-                                         return_value=[FakeProcesses()])
-
+                                         return_value=retval)
         with process_iter as mock_process_iter:
             self._mon_api._detect()
             self.assertTrue(mock_process_iter.called)