Add config option `http_retries`

This option allows to configure Number of times nova or ironic client
should retry on any failed http call.
Default value for this new option is "3".

Conflicts:
    neutron/notifiers/ironic.py
    neutron/notifiers/nova.py
    neutron/tests/unit/notifiers/test_nova.py

Change-Id: I795ee7ca729646be0411a1232bf218015c65010f
Closes-Bug: #1883712
(cherry picked from commit e94511cd25)

neutron/conf/common.py

@@ -125,7 +125,15 @@ core_opts = [
                       'this value without modification. For overlay networks '
                       'such as VXLAN, neutron automatically subtracts the '
                       'overlay protocol overhead from this value. Defaults '
-                      'to 1500, the standard value for Ethernet.'))
+                      'to 1500, the standard value for Ethernet.')),
+    cfg.IntOpt('http_retries', default=3, min=0,
+               help=_("Number of times client connections (nova, ironic) "
+                      "should be retried on a failed HTTP call. 0 (zero) means"
+                      "connection is attempted only once (not retried). "
+                      "Setting to any positive integer means that on failure "
+                      "the connection is retried that many times. "
+                      "For example, setting to 3 means total attempts to "
+                      "connect will be 4."))
 ]
 
 core_cli_opts = [

neutron/notifiers/nova.py

@@ -70,6 +70,7 @@ class Notifier(object):
             session=session,
             region_name=cfg.CONF.nova.region_name,
             endpoint_type=cfg.CONF.nova.endpoint_type,
+            connect_retries=cfg.CONF.http_retries,
             extensions=extensions)
         self.batch_notifier = batch_notifier.BatchNotifier(
             cfg.CONF.send_events_interval, self.send_events)

neutron/tests/unit/notifiers/test_nova.py

@@ -334,6 +334,7 @@ class TestNovaNotify(base.BaseTestCase):
         nova.Notifier()
         mock_client.assert_called_once_with(
                                 api_versions.APIVersion(nova.NOVA_API_VERSION),
+                                connect_retries=3,
                                 session=mock.ANY,
                                 region_name=cfg.CONF.nova.region_name,
                                 endpoint_type='public',
@@ -344,6 +345,7 @@ class TestNovaNotify(base.BaseTestCase):
         nova.Notifier()
         mock_client.assert_called_once_with(
                                 api_versions.APIVersion(nova.NOVA_API_VERSION),
+                                connect_retries=3,
                                 session=mock.ANY,
                                 region_name=cfg.CONF.nova.region_name,
                                 endpoint_type='internal',

releasenotes/notes/Add-http_retries-config-option-b81dd29c03ba8c6a.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    A new configuration option ``http_retries`` was added. This option allows
+    configuring the number of times the nova or ironic client should retry on
+    a failed HTTP call.