Only perform health check if DNS is enabled

go.mod

@@ -4,8 +4,8 @@ go 1.13
 
 require (
 	github.com/gardener/external-dns-management v0.7.6 // indirect
-	github.com/gardener/gardener v1.0.1-0.20200213093126-7a6123b6ae21
-	github.com/gardener/gardener-extensions v1.3.1-0.20200219155613-f5f526846320
+	github.com/gardener/gardener v1.1.6
+	github.com/gardener/gardener-extensions v1.5.0
 	github.com/go-logr/logr v0.1.0
 	github.com/gobuffalo/packr/v2 v2.1.0
 	github.com/golang/mock v1.3.1
@@ -14,10 +14,10 @@ require (
 	github.com/pkg/errors v0.9.0
 	github.com/spf13/cobra v0.0.5
 	github.com/spf13/pflag v1.0.5
-	k8s.io/api v0.16.4
+	k8s.io/api v0.17.0
 	k8s.io/apimachinery v0.17.0
 	k8s.io/client-go v11.0.1-0.20190409021438-1a26190bd76a+incompatible
-	k8s.io/component-base v0.16.4
+	k8s.io/component-base v0.17.0
 	sigs.k8s.io/controller-runtime v0.4.0
 )
 
@@ -26,5 +26,6 @@ replace (
 	k8s.io/apimachinery => k8s.io/apimachinery v0.0.0-20190913080033-27d36303b655 // kubernetes-1.16.0
 	k8s.io/apiserver => k8s.io/apiserver v0.0.0-20190918160949-bfa5e2e684ad // kubernetes-1.16.0
 	k8s.io/client-go => k8s.io/client-go v0.0.0-20190918160344-1fbdaa4c8d90 // kubernetes-1.16.0
+	k8s.io/component-base => k8s.io/component-base v0.0.0-20190918160511-547f6c5d7090 // kubernetes-1.16.0
 	k8s.io/kube-aggregator => k8s.io/kube-aggregator v0.0.0-20190918161219-8c8f079fddc3 // kubernetes-1.16.0
 )

pkg/controller/healthcheck/add.go

@@ -19,6 +19,7 @@ import (
 	"github.com/gardener/gardener-extension-shoot-dns-service/pkg/controller/config"
 	"github.com/gardener/gardener-extension-shoot-dns-service/pkg/service"
 
+	extensionscontroller "github.com/gardener/gardener-extensions/pkg/controller"
 	"github.com/gardener/gardener-extensions/pkg/controller/healthcheck"
 	healthcheckconfig "github.com/gardener/gardener-extensions/pkg/controller/healthcheck/config"
 	"github.com/gardener/gardener-extensions/pkg/controller/healthcheck/general"
@@ -31,6 +32,10 @@ import (
 // RegisterHealthChecks registers health checks for each extension resource
 // HealthChecks are grouped by extension (e.g worker), extension.type (e.g aws) and  Health Check Type (e.g SystemComponentsHealthy)
 func RegisterHealthChecks(mgr manager.Manager) error {
+	preCheckFunc := func(_ runtime.Object, cluster *extensionscontroller.Cluster) bool {
+		return cluster.Shoot.Spec.DNS != nil && cluster.Shoot.Spec.DNS.Domain != nil
+	}
+
 	opts := healthcheck.DefaultAddArgs{
 		Controller:        config.HealthConfig.ControllerOptions,
 		HealthCheckConfig: healthcheckconfig.HealthCheckConfig{SyncPeriod: config.HealthConfig.Health.HealthCheckSyncPeriod},
@@ -43,8 +48,17 @@ func RegisterHealthChecks(mgr manager.Manager) error {
 		mgr,
 		opts,
 		nil,
-		map[healthcheck.HealthCheck]string{
-			general.CheckManagedResource(dnscontroller.ShootResourcesName): string(gardencorev1beta1.ShootSystemComponentsHealthy),
-			general.CheckManagedResource(dnscontroller.SeedResourcesName):  string(gardencorev1beta1.ShootControlPlaneHealthy),
-		})
+		[]healthcheck.ConditionTypeToHealthCheck{
+			{
+				ConditionType: string(gardencorev1beta1.ShootControlPlaneHealthy),
+				HealthCheck:   general.CheckManagedResource(dnscontroller.SeedResourcesName),
+				PreCheckFunc:  preCheckFunc,
+			},
+			{
+				ConditionType: string(gardencorev1beta1.ShootSystemComponentsHealthy),
+				HealthCheck:   general.CheckManagedResource(dnscontroller.ShootResourcesName),
+				PreCheckFunc:  preCheckFunc,
+			},
+		},
+	)
 }