Support magnum-api multiple process workers

Multiple process workers support for magnum-api.
Adds new option 'workers' to group [api] of magnum.conf.

Change-Id: I0e8327ada6926602d577d1f36d384dd49426c7ee
Implements: blueprint magnum-multiple-process-workers

magnum/cmd/api.py

@@ -17,6 +17,7 @@
 import os
 import sys
 
+from oslo_concurrency import processutils
 from oslo_log import log as logging
 from oslo_reports import guru_meditation_report as gmr
 from werkzeug import serving
@@ -75,5 +76,10 @@ def main():
     LOG.info(_LI('Serving on %(proto)s://%(host)s:%(port)s'),
              dict(proto="https" if use_ssl else "http", host=host, port=port))
 
-    serving.run_simple(host, port, app,
+    workers = CONF.api.workers
+    if not workers:
+        workers = processutils.get_worker_count()
+    LOG.info(_LI('Server will handle each request in a new process up to'
+                 ' %s concurrent processes'), workers)
+    serving.run_simple(host, port, app, processes=workers,
                        ssl_context=_get_ssl_configs(use_ssl))

magnum/conf/api.py

@@ -39,7 +39,10 @@ api_service_opts = [
                     "effect. "),
     cfg.BoolOpt('enabled_ssl',
                 default=False,
-                help='Enable SSL Magnum API service')
+                help='Enable SSL Magnum API service'),
+    cfg.IntOpt('workers',
+               help='The maximum number of magnum-api processes to '
+                    'fork and run. Default to number of CPUs on the host.')
 ]
 
 

magnum/tests/unit/cmd/test_api.py

@@ -14,6 +14,8 @@
 
 import mock
 
+from oslo_concurrency import processutils
+
 from magnum.cmd import api
 from magnum.tests import base
 
@@ -32,9 +34,28 @@ class TestMagnumAPI(base.TestCase):
         app = mock_app.load_app.return_value
         mock_prep.assert_called_once_with(mock.ANY)
         mock_app.load_app.assert_called_once_with()
+        workers = processutils.get_worker_count()
         mock_run.assert_called_once_with(base.CONF.api.host,
                                          base.CONF.api.port,
-                                         app, ssl_context=None)
+                                         app, processes=workers,
+                                         ssl_context=None)
+
+    @mock.patch('werkzeug.serving.run_simple')
+    @mock.patch.object(api, 'api_app')
+    @mock.patch('magnum.common.service.prepare_service')
+    def test_api_http_config_workers(self, mock_prep, mock_app,
+                                     mock_run, mock_base):
+        fake_workers = 8
+        self.config(workers=fake_workers, group='api')
+        api.main()
+
+        app = mock_app.load_app.return_value
+        mock_prep.assert_called_once_with(mock.ANY)
+        mock_app.load_app.assert_called_once_with()
+        mock_run.assert_called_once_with(base.CONF.api.host,
+                                         base.CONF.api.port,
+                                         app, processes=fake_workers,
+                                         ssl_context=None)
 
     @mock.patch('os.path.exists')
     @mock.patch('werkzeug.serving.run_simple')
@@ -91,6 +112,8 @@ class TestMagnumAPI(base.TestCase):
         mock_app.load_app.assert_called_once_with()
         mock_exist.assert_has_calls([mock.call('tmp_crt'),
                                      mock.call('tmp_key')])
+        workers = processutils.get_worker_count()
         mock_run.assert_called_once_with(base.CONF.api.host,
                                          base.CONF.api.port, app,
+                                         processes=workers,
                                          ssl_context=('tmp_crt', 'tmp_key'))