network: skip dhcp and dns health checks on internal LB routers

An internal LB VM runs only the load balancer, but it was given the full
virtual router health check set, so the dhcp and dns checks failed on every
advanced health check run and flooded the event log. Exclude those checks for
a router whose role is internal LB, using the existing per-router
excluded-checks mechanism.

Fixes: #12658

Author: nagaboinaramgopal

server/src/main/java/com/cloud/network/router/VirtualNetworkApplianceManagerImpl.java

@@ -276,6 +276,7 @@ public class VirtualNetworkApplianceManagerImpl extends ManagerBase implements V
     private static final String FILESYSTEM_WRITABLE_TEST = "filesystem.writable.test";
     private static final String READONLY_FILESYSTEM_ERROR = "Read-only file system";
     private static final String BACKUP_ROUTER_EXCLUDED_TESTS = "gateways_check.py";
+    private static final String INTERNAL_LB_EXCLUDED_TESTS = "dhcp_check.py,dns_check.py";
     /**
      * Used regex to ensure that the value that will be passed to the VR is an acceptable value
      */
@@ -1616,6 +1617,9 @@ private SetMonitorServiceCommand createMonitorServiceCommand(DomainRouterVO rout
                 excludedTests = excludedTests.isEmpty() ? BACKUP_ROUTER_EXCLUDED_TESTS : excludedTests + "," + BACKUP_ROUTER_EXCLUDED_TESTS;
             }
         }
+        if (router.getRole() == Role.INTERNAL_LB_VM) {
+            excludedTests = excludedTests.isEmpty() ? INTERNAL_LB_EXCLUDED_TESTS : excludedTests + "," + INTERNAL_LB_EXCLUDED_TESTS;
+        }
 
         command.setAccessDetail(SetMonitorServiceCommand.ROUTER_HEALTH_CHECKS_EXCLUDED, excludedTests);
         command.setHealthChecksConfig(routerHealthCheckConfig);

server/src/test/java/com/cloud/network/router/VirtualNetworkApplianceManagerImplTest.java

@@ -67,6 +67,7 @@
 import com.cloud.user.dao.UserDao;
 import com.cloud.user.dao.UserStatisticsDao;
 import com.cloud.user.dao.UserStatsLogDao;
+import com.cloud.agent.api.routing.SetMonitorServiceCommand;
 import com.cloud.vm.DomainRouterVO;
 import com.cloud.vm.VirtualMachine;
 import com.cloud.vm.VirtualMachineManager;
@@ -91,6 +92,7 @@
 import java.util.ArrayList;
 import java.util.Date;
 import java.util.List;
+import java.util.Map;
 
 import static org.junit.Assert.assertEquals;
 import static org.mockito.ArgumentMatchers.nullable;
@@ -354,6 +356,28 @@ public void checkLogrotateTimerPatternTestMatchesWithRegex(){
         Assert.assertTrue(result);
     }
 
+    @Test
+    public void testInternalLbRouterExcludesDhcpAndDnsHealthChecks() throws Exception {
+        DomainRouterVO router = Mockito.mock(DomainRouterVO.class);
+        when(router.getId()).thenReturn(1L);
+        when(router.getInstanceName()).thenReturn("r-1-VM");
+        when(router.getDataCenterId()).thenReturn(1L);
+        when(router.getIsRedundantRouter()).thenReturn(false);
+        when(router.getRole()).thenReturn(VirtualRouter.Role.INTERNAL_LB_VM);
+        when(_routerControlHelper.getRouterControlIp(1L)).thenReturn("169.254.0.1");
+
+        java.lang.reflect.Method method = VirtualNetworkApplianceManagerImpl.class.getDeclaredMethod(
+                "createMonitorServiceCommand", DomainRouterVO.class, List.class, boolean.class, boolean.class, Map.class);
+        method.setAccessible(true);
+        SetMonitorServiceCommand command = (SetMonitorServiceCommand) method.invoke(
+                virtualNetworkApplianceManagerImpl, router, null, true, true, null);
+
+        String excluded = command.getAccessDetail(SetMonitorServiceCommand.ROUTER_HEALTH_CHECKS_EXCLUDED);
+        Assert.assertNotNull(excluded);
+        Assert.assertTrue("Internal LB VM should exclude dhcp and dns health checks, got: " + excluded,
+                excluded.contains("dhcp_check.py") && excluded.contains("dns_check.py"));
+    }
+
     @Test
     public void testFinalizeNetworkRulesForNetwork() {
         Long guestNetworkId = 10L;