Make version pinning optional

The OVN charms prepared for the upgrade from OVN 20.03 to newer
versions by enabling the version pinning by default.

Since then we have reached agreement with upstream that rolling
upgrades should work when upgrading within the previous upstream
LTS version and the next.

Having the pinning enabled by default causes unnecessary grief for
anyone already upgraded to OVN 22.03, so it's time to turn it off
by default.

We add a charm configuration option in case anyone wants to
upgrade across LTS boundaries in the future.

Closes-Bug: #2030944
Signed-off-by: Frode Nordahl <[email protected]>
(cherry picked from commit f68ecbd)

Conflicts:
	config.yaml

config.yaml

@@ -355,3 +355,19 @@ options:
       The snap channel to install the prometheus-ovs-exporter from. Setting
       this option to an empty string will result in the snap not being
       installed or removed if it has already been installed.
+  enable-version-pinning:
+    type: boolean
+    default: true
+    description: |
+      OVN is a distributed system, and special consideration must be given to
+      the process used to upgrade OVN.
+
+      In order to successfully perform a rolling upgrade, the ovn-controller
+      process needs to understand the structure of the database for the version
+      you are upgrading from and to simultaneously.
+
+      Rolling upgrades are supported as long as the span of versions used in
+      the system is within the previous and the next upstream OVN LTS version.
+
+      If you are upgrading across LTS boundaries you may need to use version
+      pinning to avoid data plane outage during the upgrade.

lib/charms/ovn_charm.py

@@ -1128,7 +1128,8 @@ def configure_ovs(self, sb_conn, mlockall_changed):
                            'external-ids:system-id={}'
                            .format(self.get_ovs_hostname()),
                            'external-ids:ovn-remote={}'.format(sb_conn),
-                           'external_ids:ovn-match-northd-version=true',
+                           'external_ids:ovn-match-northd-version={}'
+                           .format(self.options.enable_version_pinning),
                            ):
             cmd = cmd + ('--', 'set', 'open-vswitch', '.', ovs_ext_id)
         self.run(*cmd)

unit_tests/test_lib_charms_ovn_charm.py

@@ -1084,7 +1084,7 @@ def test_configure_sources(self):
 class TestOVNChassisCharm(Helper):
 
     def setUp(self):
-        super().setUp(config={
+        self.local_config = {
             'enable-hardware-offload': False,
             'enable-sriov': False,
             'enable-dpdk': False,
@@ -1097,7 +1097,9 @@ def setUp(self):
             '[{"bus": "pci", "vendor_id": "beef", "device_id": "cafe"}]',
             'ovn-source': 'distro',
             'ovs-exporter-channel': '',
-        })
+            'enable-version-pinning': False,
+        }
+        super().setUp(config=self.local_config)
 
     def test_optional_openstack_metadata(self):
         self.assertEquals(self.target.packages, ['ovn-host'])
@@ -1233,7 +1235,7 @@ def test_configure_ovs(self):
                 '--', 'set', 'open-vswitch', '.',
                 'external-ids:ovn-remote=fake-sb-conn-str',
                 '--', 'set', 'open-vswitch', '.',
-                'external_ids:ovn-match-northd-version=true',
+                'external_ids:ovn-match-northd-version=False',
             ),
         ])
         self.service_restart.assert_not_called()
@@ -1259,7 +1261,7 @@ def test_configure_ovs(self):
                 '--', 'set', 'open-vswitch', '.',
                 'external-ids:ovn-remote=fake-sb-conn-str',
                 '--', 'set', 'open-vswitch', '.',
-                'external_ids:ovn-match-northd-version=true',
+                'external_ids:ovn-match-northd-version=False',
             ),
             mock.call('ovs-vsctl', '--id', '@manager',
                       'create', 'Manager', 'target="ptcp:6640:127.0.0.1"',
@@ -1268,6 +1270,39 @@ def test_configure_ovs(self):
         ])
         assert self.service_restart.called
 
+    def test_configure_ovs_version_pinning(self):
+        self.local_config.update({'enable-version-pinning': True})
+        self.target = ovn_charm.BaseOVNChassisCharm()
+        self.patch_target('run')
+        self.patch_object(ovn_charm.OVNConfigurationAdapter, 'ovn_key')
+        self.patch_object(ovn_charm.OVNConfigurationAdapter, 'ovn_cert')
+        self.patch_object(ovn_charm.OVNConfigurationAdapter, 'ovn_ca_cert')
+        self.patch_object(ovn_charm.ch_core.host, 'service_restart')
+        self.patch_target('get_data_ip')
+        self.get_data_ip.return_value = 'fake-data-ip'
+        self.patch_target('get_ovs_hostname')
+        self.get_ovs_hostname.return_value = 'fake-ovs-hostname'
+        self.patch_target('check_if_paused')
+        self.check_if_paused.return_value = (None, None)
+        self.target.configure_ovs('fake-sb-conn-str', False)
+        self.run.assert_has_calls([
+            mock.call('ovs-vsctl', '--no-wait', 'set-ssl',
+                      mock.ANY, mock.ANY, mock.ANY),
+            mock.call(
+                'ovs-vsctl',
+                '--', 'set', 'open-vswitch', '.',
+                'external-ids:ovn-encap-type=geneve',
+                '--', 'set', 'open-vswitch', '.',
+                'external-ids:ovn-encap-ip=fake-data-ip',
+                '--', 'set', 'open-vswitch', '.',
+                'external-ids:system-id=fake-ovs-hostname',
+                '--', 'set', 'open-vswitch', '.',
+                'external-ids:ovn-remote=fake-sb-conn-str',
+                '--', 'set', 'open-vswitch', '.',
+                'external_ids:ovn-match-northd-version=True',
+            ),
+        ])
+
     def test_render_nrpe(self):
         self.patch_object(ovn_charm.nrpe, 'NRPE')
         self.patch_object(ovn_charm.nrpe, 'add_init_service_checks')