diff --git a/requirements.txt b/requirements.txt
index 20f335d..f65abf7 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,4 +4,6 @@
 #
 # Build requirements
 charm-tools>=2.4.4
+# importlib-resources 1.1.0 removed Python 3.5 support
+importlib-resources<1.1.0
 simplejson
diff --git a/src/lib/charm/openstack/ovn_chassis.py b/src/lib/charm/openstack/ovn_chassis.py
index 5b6e416..8d5ab28 100644
--- a/src/lib/charm/openstack/ovn_chassis.py
+++ b/src/lib/charm/openstack/ovn_chassis.py
@@ -11,11 +11,66 @@
 # WITHOUT 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 inspect
+
+import charmhelpers.fetch as ch_fetch
+
 import charms.ovn_charm
 
 
-class OVNChassisCharm(charms.ovn_charm.BaseOVNChassisCharm):
+class OVNSubordinateChassisCharm(object):
+    """Mix-in for subordinate-specific handling."""
+
+    @staticmethod
+    def get_os_codename_package(package, codenames, fatal=True):
+        """Override to conditionally decide based on packages in apt cache.
+
+        Please inspect parent method for documentation of parameters.
+
+        The parent method also requires a package to already be installed,
+        and on initial charm deploy the fall back is to retrieve information
+        from a source configuration option.
+
+        Since we are a subordinate charm, we do not have a source configuration
+        option, thus we want to make the decision based on what is currently
+        available in the system APT cache alone. Our principle charm should
+        already have configured the system with the desired UCA pocket enabled.
+        """
+        # When the method is called outside of the context of the select
+        # release handler we do want it to assert presence of an installed
+        # package, as it is then used to detect available upgrades.
+        if (not inspect.currentframe().f_back.f_code.co_name == ''
+                'default_select_release'):
+            return super().get_os_codename_package(
+                package, codenames, fatal=fatal)
+
+        cache = ch_fetch.apt_cache()
+        try:
+            pkg = cache[package]
+        except KeyError:
+            if not fatal:
+                return
+            raise ValueError(
+                'Could not determine version of package with no installation '
+                'candidate: {}'.format(package))
+        ver = ch_fetch.apt_pkg.upstream_version(pkg.version)
+        major_ver = ver.split('.')[0]
+        if (package in codenames and
+                major_ver in codenames[package]):
+            return codenames[package][major_ver]
+
+
+class TrainOVNChassisCharm(OVNSubordinateChassisCharm,
+                           charms.ovn_charm.BaseTrainOVNChassisCharm):
     # OpenvSwitch and OVN is distributed as part of the Ubuntu Cloud Archive
     # Pockets get their name from OpenStack releases
     release = 'train'
     name = 'ovn-chassis'
+
+
+class UssuriOVNChassisCharm(OVNSubordinateChassisCharm,
+                            charms.ovn_charm.BaseUssuriOVNChassisCharm):
+    # OpenvSwitch and OVN is distributed as part of the Ubuntu Cloud Archive
+    # Pockets get their name from OpenStack releases
+    release = 'ussuri'
+    name = 'ovn-chassis'
diff --git a/src/metadata.yaml b/src/metadata.yaml
index 96768c2..072d657 100644
--- a/src/metadata.yaml
+++ b/src/metadata.yaml
@@ -9,6 +9,7 @@ tags:
 series:
   - bionic
   - eoan
+  - focal
 subordinate: true
 extra-bindings:
   data:
diff --git a/src/tests/bundles/bionic.yaml b/src/tests/bundles/bionic-train.yaml
similarity index 87%
rename from src/tests/bundles/bionic.yaml
rename to src/tests/bundles/bionic-train.yaml
index 5755b46..b5025a8 100644
--- a/src/tests/bundles/bionic.yaml
+++ b/src/tests/bundles/bionic-train.yaml
@@ -23,8 +23,10 @@ applications:
     options:
       source: cloud:bionic-train
   magpie:
-    charm: cs:~admcleod/magpie
+    charm: cs:~openstack-charmers-next/magpie
     num_units: 2
+    options:
+      source: cloud:bionic-train
   ovn-chassis:
     series: bionic
     charm: cs:~openstack-charmers-next/ovn-chassis
diff --git a/src/tests/bundles/bionic-ussuri.yaml b/src/tests/bundles/bionic-ussuri.yaml
new file mode 100644
index 0000000..8c26ec8
--- /dev/null
+++ b/src/tests/bundles/bionic-ussuri.yaml
@@ -0,0 +1,32 @@
+series: bionic
+relations:
+- - vault:shared-db
+  - mysql:shared-db
+- - ovn-central:certificates
+  - vault:certificates
+- - magpie:juju-info
+  - ovn-chassis:juju-info
+- - ovn-chassis:ovsdb
+  - ovn-central:ovsdb
+- - ovn-chassis:certificates
+  - vault:certificates
+applications:
+  mysql:
+    charm: cs:~openstack-charmers-next/percona-cluster
+    num_units: 1
+  vault:
+    charm: cs:~openstack-charmers-next/vault
+    num_units: 1
+  ovn-central:
+    charm: cs:~openstack-charmers-next/ovn-central
+    num_units: 3
+    options:
+      source: cloud:bionic-ussuri/proposed
+  magpie:
+    charm: cs:~openstack-charmers-next/magpie
+    num_units: 2
+    options:
+      source: cloud:bionic-ussuri/proposed
+  ovn-chassis:
+    series: bionic
+    charm: cs:~openstack-charmers-next/ovn-chassis
diff --git a/src/tests/bundles/eoan.yaml b/src/tests/bundles/eoan.yaml
index 760ba9a..2c790d3 100644
--- a/src/tests/bundles/eoan.yaml
+++ b/src/tests/bundles/eoan.yaml
@@ -1,7 +1,9 @@
 series: eoan
 relations:
+- - vault-mysql-router:db-router
+  - mysql-innodb-cluster:db-router
 - - vault:shared-db
-  - mysql:shared-db
+  - vault-mysql-router:shared-db
 - - ovn-central:certificates
   - vault:certificates
 - - magpie:juju-info
@@ -11,9 +13,11 @@ relations:
 - - ovn-chassis:certificates
   - vault:certificates
 applications:
-  mysql:
+  mysql-innodb-cluster:
     charm: cs:~openstack-charmers-next/mysql-innodb-cluster
     num_units: 3
+  vault-mysql-router:
+    charm: cs:~openstack-charmers-next/mysql-router
   vault:
     charm: cs:~openstack-charmers-next/vault
     num_units: 1
@@ -21,7 +25,7 @@ applications:
     charm: cs:~openstack-charmers-next/ovn-central
     num_units: 3
   magpie:
-    charm: cs:~admcleod/magpie
+    charm: cs:~openstack-charmers-next/magpie
     num_units: 2
   ovn-chassis:
     series: eoan
diff --git a/src/tests/bundles/focal.yaml b/src/tests/bundles/focal.yaml
new file mode 100644
index 0000000..958973d
--- /dev/null
+++ b/src/tests/bundles/focal.yaml
@@ -0,0 +1,31 @@
+series: focal
+relations:
+- - vault-mysql-router:db-router
+  - mysql-innodb-cluster:db-router
+- - vault:shared-db
+  - vault-mysql-router:shared-db
+  - vault:certificates
+- - magpie:juju-info
+  - ovn-chassis:juju-info
+- - ovn-chassis:ovsdb
+  - ovn-central:ovsdb
+- - ovn-chassis:certificates
+  - vault:certificates
+applications:
+  mysql-innodb-cluster:
+    charm: cs:~openstack-charmers-next/mysql-innodb-cluster
+    num_units: 3
+  vault-mysql-router:
+    charm: cs:~openstack-charmers-next/mysql-router
+  vault:
+    charm: cs:~openstack-charmers-next/vault
+    num_units: 1
+  ovn-central:
+    charm: cs:~openstack-charmers-next/ovn-central
+    num_units: 3
+  magpie:
+    charm: cs:~openstack-charmers-next/magpie
+    num_units: 2
+  ovn-chassis:
+    series: focal
+    charm: cs:~openstack-charmers-next/ovn-chassis
diff --git a/src/tests/tests.yaml b/src/tests/tests.yaml
index 917e3a7..ddbb6b6 100644
--- a/src/tests/tests.yaml
+++ b/src/tests/tests.yaml
@@ -1,9 +1,12 @@
 charm_name: ovn-chassis
 gate_bundles:
+- bionic-train
 - eoan
-- bionic
+- bionic-ussuri
 smoke_bundles:
-- bionic
+- bionic-ussuri
+dev_bundles:
+- focal
 target_deploy_status:
   magpie:
     workload-status-message: icmp ok
diff --git a/test-requirements.txt b/test-requirements.txt
index 14b380e..c43a8db 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -3,11 +3,10 @@
 # requirements management in charms via bot-control.  Thank you.
 #
 # Lint and unit test requirements
-flake8>=2.2.4,<=2.4.1
-stestr>=2.2.0
-requests>=2.18.4
-charms.reactive
-mock>=1.2
-nose>=1.3.7
 coverage>=3.6
+mock>=1.2
+pep8>=1.7.0
+flake8>=2.2.4
+os-testr>=0.4.1
+
 git+https://github.com/openstack/charms.openstack.git#egg=charms.openstack
diff --git a/tox.ini b/tox.ini
index 23750a8..a45c381 100644
--- a/tox.ini
+++ b/tox.ini
@@ -77,4 +77,4 @@ commands = {posargs}
 
 [flake8]
 # E402 ignore necessary for path append before sys module import in actions
-ignore = E402
+ignore = E402,W504
diff --git a/unit_tests/__init__.py b/unit_tests/__init__.py
index 5408a9d..4670b81 100644
--- a/unit_tests/__init__.py
+++ b/unit_tests/__init__.py
@@ -22,21 +22,45 @@ import charms_openstack.test_mocks  # noqa
 charms_openstack.test_mocks.mock_charmhelpers()
 
 import mock
-import charms
+
+
+class _fake_decorator(object):
+
+    def __init__(self, *args):
+        pass
+
+    def __call__(self, f):
+        return f
+
+
+charms = mock.MagicMock()
+sys.modules['charms'] = charms
 charms.leadership = mock.MagicMock()
-keystoneauth1 = mock.MagicMock()
-neutronclient = mock.MagicMock()
 sys.modules['charms.leadership'] = charms.leadership
-keystoneauth1 = mock.MagicMock()
-novaclient = mock.MagicMock()
-neutron_lib = mock.MagicMock()
+charms.reactive = mock.MagicMock()
+charms.reactive.when = _fake_decorator
+charms.reactive.when_all = _fake_decorator
+charms.reactive.when_any = _fake_decorator
+charms.reactive.when_not = _fake_decorator
+charms.reactive.when_none = _fake_decorator
+charms.reactive.when_not_all = _fake_decorator
+charms.reactive.not_unless = _fake_decorator
+charms.reactive.when_file_changed = _fake_decorator
+charms.reactive.collect_metrics = _fake_decorator
+charms.reactive.meter_status_changed = _fake_decorator
+charms.reactive.only_once = _fake_decorator
+charms.reactive.hook = _fake_decorator
+charms.reactive.bus = mock.MagicMock()
+charms.reactive.flags = mock.MagicMock()
+charms.reactive.relations = mock.MagicMock()
+sys.modules['charms.reactive'] = charms.reactive
+sys.modules['charms.reactive.bus'] = charms.reactive.bus
+sys.modules['charms.reactive.bus'] = charms.reactive.decorators
+sys.modules['charms.reactive.flags'] = charms.reactive.flags
+sys.modules['charms.reactive.relations'] = charms.reactive.relations
 sys.modules['charms.leadership'] = charms.leadership
-sys.modules['keystoneauth1'] = keystoneauth1
-sys.modules['novaclient'] = novaclient
-sys.modules['neutronclient'] = neutronclient
-sys.modules['neutronclient.v2_0'] = neutronclient.v2_0
-sys.modules['neutron_lib'] = neutron_lib
-sys.modules['neutron_lib.constants'] = neutron_lib.constants
+netaddr = mock.MagicMock()
+sys.modules['netaddr'] = netaddr
 import reactive
 reactive.ovn_chassis_charm_handlers = mock.MagicMock()
 reactive.ovn_chassis_charm_handlers.OVN_CHASSIS_ENABLE_HANDLERS_FLAG = \