Migrate API service to use native threading

This commit performs the first service migration from eventlet to
standard python threading, focusing on the `designate-api` service.

The API service main entrypoint (designate/cmd/api.py) now explicitly
initializes oslo_service threading backend. It will be removed when
the migration is complete.

Change-Id: Ic15de389f01a42f8dc918511e9a60df1449f1bed
Signed-off-by: Omer <oschwart@redhat.com>

designate/cmd/threading/api.py

@@ -41,4 +41,7 @@ def main():
     heartbeat = heartbeat_emitter.get_heartbeat_emitter(server.service_name)
     service.serve(server, workers=CONF['service:api'].workers)
     heartbeat.start()
-    service.wait()
+    try:
+        service.wait()
+    finally:
+        heartbeat.stop()

designate/conf/api.py

@@ -23,8 +23,8 @@ API_GROUP = cfg.OptGroup(
 API_OPTS = [
     cfg.IntOpt('workers',
                help='Number of api worker processes to spawn'),
-    cfg.IntOpt('threads', default=1000,
-               help='Number of api greenthreads to spawn'),
+    cfg.IntOpt('threads', default=100,
+               help='Number of api threads to spawn'),
     cfg.BoolOpt('enable_host_header', default=True,
                 help='Enable host request headers'),
     cfg.StrOpt('api_base_uri', default='http://127.0.0.1:9001/',

designate/network_api/base.py

@@ -13,7 +13,7 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.
-import eventlet.patcher
+from dns import reversename
 from oslo_log import log as logging
 
 import designate.conf
@@ -23,9 +23,6 @@ from designate.plugin import DriverPlugin
 
 CONF = designate.conf.CONF
 LOG = logging.getLogger(__name__)
-# NOTE(kiall): This is a workaround for bug #1424621, a broken reimplementation
-#              of eventlet's 0.17.0 monkey patching of dnspython.
-reversename = eventlet.patcher.original('dns.reversename')
 
 
 class NetworkAPI(DriverPlugin):

designate/tests/unit/cmd/test_cmd.py

@@ -14,7 +14,6 @@ from unittest import mock
 from oslo_config import fixture as cfg_fixture
 import oslotest.base
 
-from designate.cmd.eventlet import api
 from designate.cmd.eventlet import central
 from designate.cmd.eventlet import mdns
 from designate.cmd.eventlet import producer
@@ -26,6 +25,10 @@ import designate.conf
 CONF = designate.conf.CONF
 
 
+with mock.patch('oslo_service.backend.init_backend'):
+    from designate.cmd.threading import api
+
+
 @mock.patch('designate.service.wait')
 @mock.patch('designate.service.serve')
 @mock.patch('designate.heartbeat_emitter.get_heartbeat_emitter')

releasenotes/notes/api-threading-migration-7b0b9c045fd9496d.yaml

@@ -0,0 +1,8 @@
+---
+upgrade:
+  - |
+    The designate-api service has been migrated from eventlet to use
+    native Python threading.
+
+    The default number of API threads has been reduced from 1000 to 100
+    to reflect the change from eventlet greenthreads to native OS threads.

setup.cfg

@@ -53,7 +53,7 @@ oslo.policy.enforcer =
 
 console_scripts =
     designate-rootwrap = oslo_rootwrap.cmd:main
-    designate-api = designate.cmd.eventlet.api:main
+    designate-api = designate.cmd.threading.api:main
     designate-central = designate.cmd.eventlet.central:main
     designate-manage = designate.cmd.eventlet.manage:main
     designate-mdns = designate.cmd.eventlet.mdns:main