Add keepalived-healthcheck-interval config option

Defaults to 30s (i.e. enabled) but also allows disabling
healthchecks by setting to 0.

Change-Id: I49603c22d8085aabd6085058e4d4eb9c74e84a20
Closes-Bug: #1890900

config.yaml

@@ -362,3 +362,11 @@ options:
     description: |
       Manually disable lbaas services. Set this option to True if Octavia
       is used with neutron. This option is ignored for Train+ OpenStack.
+  keepalived-healthcheck-interval:
+    type: int
+    default: 30
+    description: |
+      By default all HA routers will check their external network gateway
+      by sending a ping and if that fails they trigger a vrrp transition. This
+      option defines how frequently this check is performed. Setting this value
+      to 0 will disable the healthchecks.

hooks/neutron_contexts.py

@@ -175,6 +175,8 @@ class NeutronGatewayContext(NeutronAPIContext):
             'availability_zone': get_availability_zone(),
             'enable_nfg_logging': api_settings['enable_nfg_logging'],
             'ovsdb_timeout': config('ovsdb-timeout'),
+            'keepalived_healthcheck_interval':
+            config('keepalived-healthcheck-interval')
         }
 
         ctxt['local_ip'] = get_local_ip()

templates/newton/l3_agent.ini

@@ -30,8 +30,8 @@ gateway_external_network_id = {{ ext_net_id }}
 external_network_bridge = br-ex
 {% endif -%}
 agent_mode = {{ agent_mode }}
-{% if use_l3ha -%}
-ha_vrrp_health_check_interval = 30
+{% if use_l3ha and keepalived_healthcheck_interval -%}
+ha_vrrp_health_check_interval = {{ keepalived_healthcheck_interval }}
 {% endif -%}
 
 [AGENT]

templates/queens/l3_agent.ini

@@ -25,8 +25,8 @@ gateway_external_network_id = {{ ext_net_id }}
 external_network_bridge = br-ex
 {% endif -%}
 agent_mode = {{ agent_mode }}
-{% if use_l3ha -%}
-ha_vrrp_health_check_interval = 30
+{% if use_l3ha and keepalived_healthcheck_interval -%}
+ha_vrrp_health_check_interval = {{ keepalived_healthcheck_interval }}
 {% endif -%}
 
 [AGENT]

templates/rocky/l3_agent.ini

@@ -25,8 +25,8 @@ gateway_external_network_id = {{ ext_net_id }}
 external_network_bridge = br-ex
 {% endif -%}
 agent_mode = {{ agent_mode }}
-{% if use_l3ha -%}
-ha_vrrp_health_check_interval = 30
+{% if use_l3ha and keepalived_healthcheck_interval -%}
+ha_vrrp_health_check_interval = {{ keepalived_healthcheck_interval }}
 {% endif -%}
 
 [AGENT]

templates/stein/l3_agent.ini

@@ -25,8 +25,8 @@ gateway_external_network_id = {{ ext_net_id }}
 external_network_bridge = br-ex
 {% endif -%}
 agent_mode = {{ agent_mode }}
-{% if use_l3ha -%}
-ha_vrrp_health_check_interval = 30
+{% if use_l3ha and keepalived_healthcheck_interval -%}
+ha_vrrp_health_check_interval = {{ keepalived_healthcheck_interval }}
 {% endif -%}
 
 [AGENT]

unit_tests/test_neutron_contexts.py

@@ -204,6 +204,8 @@ class TestNeutronGatewayContext(CharmTestCase):
 
         self.test_config.set('ovsdb-timeout', 10)
 
+        self.test_config.set('keepalived-healthcheck-interval', 0)
+
         self.network_get_primary_address.side_effect = NotImplementedError
         self.unit_get.return_value = '10.5.0.1'
         # Provided by neutron-api relation
@@ -237,6 +239,7 @@ class TestNeutronGatewayContext(CharmTestCase):
             'nfg_log_output_base': '/var/log/firewall-logs',
             'nfg_log_rate_limit': 100,
             'ovsdb_timeout': 10,
+            'keepalived_healthcheck_interval': 0,
         })
 
     @patch.object(neutron_contexts, 'validate_nfg_log_path', lambda x: x)
@@ -299,6 +302,7 @@ class TestNeutronGatewayContext(CharmTestCase):
             'nfg_log_output_base': None,
             'nfg_log_rate_limit': None,
             'ovsdb_timeout': 60,
+            'keepalived_healthcheck_interval': 30,
         })
 
     @patch('os.environ.get')