diff --git a/neutron/tests/fullstack/resources/config.py b/neutron/tests/fullstack/resources/config.py
index 17ba6195ea5..9d469cefe41 100644
--- a/neutron/tests/fullstack/resources/config.py
+++ b/neutron/tests/fullstack/resources/config.py
@@ -82,7 +82,7 @@ class NeutronConfigFixture(ConfigFixture):
                      'password': rabbitmq_environment.password,
                      'host': rabbitmq_environment.host,
                      'vhost': rabbitmq_environment.vhost},
-                'api_workers': '2',
+                'api_workers': str(env_desc.api_workers),
             },
             'database': {
                 'connection': connection,
diff --git a/neutron/tests/fullstack/resources/environment.py b/neutron/tests/fullstack/resources/environment.py
index a2bb2f1f961..f42ae0c5cb5 100644
--- a/neutron/tests/fullstack/resources/environment.py
+++ b/neutron/tests/fullstack/resources/environment.py
@@ -40,7 +40,8 @@ class EnvironmentDescription(object):
                  global_mtu=constants.DEFAULT_NETWORK_MTU,
                  debug_iptables=False, log=False, report_bandwidths=False,
                  has_placement=False, placement_port=None,
-                 dhcp_scheduler_class=None, ml2_extension_drivers=None):
+                 dhcp_scheduler_class=None, ml2_extension_drivers=None,
+                 api_workers=1):
         self.network_type = network_type
         self.l2_pop = l2_pop
         self.qos = qos
@@ -62,6 +63,7 @@ class EnvironmentDescription(object):
         if self.log:
             self.service_plugins += ',log'
         self.ml2_extension_drivers = ml2_extension_drivers
+        self.api_workers = api_workers
 
     @property
     def tunneling_enabled(self):
diff --git a/neutron/tests/fullstack/test_dhcp_agent.py b/neutron/tests/fullstack/test_dhcp_agent.py
index 6f0936fcbe5..a11a8ac1d59 100644
--- a/neutron/tests/fullstack/test_dhcp_agent.py
+++ b/neutron/tests/fullstack/test_dhcp_agent.py
@@ -38,6 +38,7 @@ class BaseDhcpAgentTest(base.BaseFullStackTestCase):
     ]
     boot_vm_for_test = True
     dhcp_scheduler_class = None
+    api_workers = 1
 
     def setUp(self):
         host_descriptions = [
@@ -52,6 +53,7 @@ class BaseDhcpAgentTest(base.BaseFullStackTestCase):
                 arp_responder=False,
                 agent_down_time=self.agent_down_time,
                 dhcp_scheduler_class=self.dhcp_scheduler_class,
+                api_workers=self.api_workers,
             ),
             host_descriptions)
 
@@ -205,6 +207,7 @@ class TestDhcpAgentHARaceCondition(BaseDhcpAgentTest):
     agent_down_time = 30
     number_of_hosts = 2
     boot_vm_for_test = False
+    api_workers = 2
     dhcp_scheduler_class = ('neutron.tests.fullstack.schedulers.dhcp.'
                             'AlwaysTheOtherAgentScheduler')
 
diff --git a/tox.ini b/tox.ini
index 576bd69e27a..f8f9f81e995 100644
--- a/tox.ini
+++ b/tox.ini
@@ -76,7 +76,7 @@ deps =
 commands =
   {toxinidir}/tools/generate_dhclient_script_for_fullstack.sh {envdir}
   {toxinidir}/tools/deploy_rootwrap.sh {toxinidir} {envdir}/etc {envdir}/bin
-  stestr run --concurrency 4 {posargs}
+  stestr run --concurrency 3 {posargs}
 
 [testenv:dsvm-fullstack-gate]
 setenv = {[testenv:dsvm-fullstack]setenv}
diff --git a/zuul.d/base.yaml b/zuul.d/base.yaml
index 4342d508bda..fc7c7e04ebe 100644
--- a/zuul.d/base.yaml
+++ b/zuul.d/base.yaml
@@ -24,6 +24,7 @@
       devstack_services:
         # Ignore any default set by devstack. Emit a "disable_all_services".
         base: false
+        etcd3: false
       devstack_localrc:
         INSTALL_TESTONLY_PACKAGES: true
         DATABASE_PASSWORD: stackdb