Merge ~blake-rouse/maas:fix-1768575-uvloop-rack into maas:master

[Blake Rouse]

LP: #1768575 - Re-enable the DHCP probing service, but don't use uvloop in the rackd. Only use uvloop in the regiond. Once authbind is removed then uvloop can be re-enabled in the rack.

[Andres Rodriguez (andreserl)]

lgtm!

review: Approve

[Newell Jensen (newell-jensen)]

LGTM.

review: Approve

diff --git a/src/maasserver/server.py b/src/maasserver/server.py
index a1e4eaf..205a9e1 100644
--- a/src/maasserver/server.py
+++ b/src/maasserver/server.py
@@ -13,20 +13,37 @@ os.environ.setdefault(
     "DJANGO_SETTINGS_MODULE", "maasserver.djangosettings.settings")
 
 
+def installUvloop():
+    """Install uvloop to asyncio to use."""
+    # XXX blake_r: LP: #1768575 - This is only done for the regiond, the rackd
+    # uses the standard asyncio reactor. Once rackd removes the need for
+    # authbind then it can be moved back into the region and this can be
+    # removed.
+    import asyncio
+    try:
+        import uvloop
+        asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
+    except ImportError:
+        pass
+
+
 def runMasterServices():
     """Run the maas-regiond master services."""
+    installUvloop()
     from provisioningserver.server import runService
     runService("maas-regiond-master")
 
 
 def runAllInOneServices():
     """Run the maas-regiond all-in-one services."""
+    installUvloop()
     from provisioningserver.server import runService
     runService("maas-regiond-all")
 
 
 def runWorkerServices():
     """Run the worker service."""
+    installUvloop()
     from provisioningserver.server import runService
     runService("maas-regiond-worker")
 
diff --git a/src/provisioningserver/plugin.py b/src/provisioningserver/plugin.py
index 4f0a88a..98c7e31 100644
--- a/src/provisioningserver/plugin.py
+++ b/src/provisioningserver/plugin.py
@@ -183,11 +183,7 @@ class ProvisioningServiceMaker:
         # Other services that make up the MAAS Region Controller.
         yield self._makeRPCPingService(rpc_service, clock=clock)
         yield self._makeNetworksMonitoringService(rpc_service, clock=clock)
-        # XXX blake_r: #1768575 - DHCP probing service using `socket.bind`
-        # with authbind and uvloop causes `socket.bind` to block indefinitely.
-        # Disable the DHCP probing service until its moved to use its own
-        # subprocess.
-        # yield self._makeDHCPProbeService(rpc_service)
+        yield self._makeDHCPProbeService(rpc_service)
         yield self._makeLeaseSocketService(rpc_service)
         yield self._makeNodePowerMonitorService()
         yield self._makeServiceMonitorService(rpc_service)
diff --git a/src/provisioningserver/server.py b/src/provisioningserver/server.py
index e305a5f..aaf7b01 100644
--- a/src/provisioningserver/server.py
+++ b/src/provisioningserver/server.py
@@ -5,17 +5,17 @@
 
 # Install the asyncio reactor with uvloop. This must be done before any other
 # twisted code is imported.
-import asyncio
 import sys
 
 from twisted.internet import asyncioreactor
 
-
-try:
-    import uvloop
-    asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
-except ImportError:
-    pass
+# XXX blake_r: LP: #1768575 - Disable uvloop on the rackd process because
+# forking with uvloop from authbind causes the rackd to lock up.
+# try:
+#     import uvloop
+#     asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
+# except ImportError:
+#     pass
 asyncioreactor.install()
 
 
diff --git a/src/provisioningserver/tests/test_plugin.py b/src/provisioningserver/tests/test_plugin.py
index 130cdfc..a253ea8 100644
--- a/src/provisioningserver/tests/test_plugin.py
+++ b/src/provisioningserver/tests/test_plugin.py
@@ -22,6 +22,9 @@ from provisioningserver.plugin import (
     Options,
     ProvisioningServiceMaker,
 )
+from provisioningserver.rackdservices.dhcp_probe_service import (
+    DHCPProbeService,
+)
 from provisioningserver.rackdservices.image import BootImageEndpointService
 from provisioningserver.rackdservices.image_download_service import (
     ImageDownloadService,
@@ -105,7 +108,7 @@ class TestProvisioningServiceMaker(MAASTestCase):
         service = service_maker.makeService(options, clock=None)
         self.assertIsInstance(service, MultiService)
         expected_services = [
-            "networks_monitor", "image_download",
+            "dhcp_probe", "networks_monitor", "image_download",
             "lease_socket_service", "node_monitor", "ntp", "rpc", "rpc-ping",
             "tftp", "image_service", "service_monitor",
             ]
@@ -129,7 +132,7 @@ class TestProvisioningServiceMaker(MAASTestCase):
         service = service_maker.makeService(options, clock=None)
         self.assertIsInstance(service, MultiService)
         expected_services = [
-            "networks_monitor", "image_download",
+            "dhcp_probe", "networks_monitor", "image_download",
             "lease_socket_service", "node_monitor", "ntp", "rpc", "rpc-ping",
             "tftp", "image_service", "service_monitor",
             ]
@@ -188,13 +191,12 @@ class TestProvisioningServiceMaker(MAASTestCase):
         networks_monitor = service.getServiceNamed("networks_monitor")
         self.assertIsInstance(networks_monitor, RackNetworksMonitoringService)
 
-    # XXX blake_r: #1768575 - Disabled DHCP probing service.
-    # def test_dhcp_probe_service(self):
-    #     options = Options()
-    #     service_maker = ProvisioningServiceMaker("Spike", "Milligan")
-    #     service = service_maker.makeService(options, clock=None)
-    #     dhcp_probe = service.getServiceNamed("dhcp_probe")
-    #     self.assertIsInstance(dhcp_probe, DHCPProbeService)
+    def test_dhcp_probe_service(self):
+        options = Options()
+        service_maker = ProvisioningServiceMaker("Spike", "Milligan")
+        service = service_maker.makeService(options, clock=None)
+        dhcp_probe = service.getServiceNamed("dhcp_probe")
+        self.assertIsInstance(dhcp_probe, DHCPProbeService)
 
     def test_service_monitor_service(self):
         options = Options()
diff --git a/utilities/check-imports b/utilities/check-imports
index 853711a..1067977 100755
--- a/utilities/check-imports
+++ b/utilities/check-imports
@@ -228,7 +228,6 @@ RackControllerRule = Rule(
     Allow("tempita"),
     Allow("tftp|tftp.**"),
     Allow("twisted.**"),
-    Allow("uvloop"),
     Allow("yaml"),
     Allow("zope.interface|zope.interface.**"),
     Allow(StandardLibraries),
@@ -280,6 +279,7 @@ RegionControllerRule = Rule(
     Allow("simplestreams.**"),
     Allow("tempita"),
     Allow("twisted.**"),
+    Allow("uvloop"),
     Allow("yaml"),
     Allow("zope.interface|zope.interface.**"),
     Allow("oauthlib.oauth1"),