feat: add annotation and label filters to Ambassador Host Source

docs/sources/sources.md

@@ -2,7 +2,7 @@
 
 | Source                          | Resources                                                                     | annotation-filter | label-filter |
 |---------------------------------|-------------------------------------------------------------------------------|-------------------|--------------|
-| ambassador-host                 | Host.getambassador.io                                                         |                   |              |
+| ambassador-host                 | Host.getambassador.io                                                         | Yes               | Yes          |
 | connector                       |                                                                               |                   |              |
 | contour-httpproxy               | HttpProxy.projectcontour.io                                                   | Yes               |              |
 | cloudfoundry                    |                                                                               |                   |              |

pkg/apis/externaldns/types.go

@@ -438,7 +438,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("openshift-router-name", "if source is openshift-route then you can pass the ingress controller name. Based on this name external-dns will select the respective router from the route status and map that routerCanonicalHostname to the route host while creating a CNAME record.").StringVar(&cfg.OCPRouterName)
 	app.Flag("namespace", "Limit resources queried for endpoints to a specific namespace (default: all namespaces)").Default(defaultConfig.Namespace).StringVar(&cfg.Namespace)
 	app.Flag("annotation-filter", "Filter resources queried for endpoints by annotation, using label selector semantics").Default(defaultConfig.AnnotationFilter).StringVar(&cfg.AnnotationFilter)
-	app.Flag("label-filter", "Filter resources queried for endpoints by label selector; currently supported by source types crd, gateway-httproute, gateway-grpcroute, gateway-tlsroute, gateway-tcproute, gateway-udproute, ingress, node, openshift-route, and service").Default(defaultConfig.LabelFilter).StringVar(&cfg.LabelFilter)
+	app.Flag("label-filter", "Filter resources queried for endpoints by label selector; currently supported by source types crd, gateway-httproute, gateway-grpcroute, gateway-tlsroute, gateway-tcproute, gateway-udproute, ingress, node, openshift-route, service and ambassador-host").Default(defaultConfig.LabelFilter).StringVar(&cfg.LabelFilter)
 	app.Flag("ingress-class", "Require an Ingress to have this class name (defaults to any class; specify multiple times to allow more than one class)").StringsVar(&cfg.IngressClassNames)
 	app.Flag("fqdn-template", "A templated string that's used to generate DNS names from sources that don't define a hostname themselves, or to add a hostname suffix when paired with the fake source (optional). Accepts comma separated list for multiple global FQDN.").Default(defaultConfig.FQDNTemplate).StringVar(&cfg.FQDNTemplate)
 	app.Flag("combine-fqdn-annotation", "Combine FQDN template and Annotations instead of overwriting").BoolVar(&cfg.CombineFQDNAndAnnotation)

source/ambassador_host.go

@@ -57,8 +57,10 @@ type ambassadorHostSource struct {
 	dynamicKubeClient      dynamic.Interface
 	kubeClient             kubernetes.Interface
 	namespace              string
+	annotationFilter       string
 	ambassadorHostInformer informers.GenericInformer
 	unstructuredConverter  *unstructuredConverter
+	labelSelector          labels.Selector
 }
 
 // NewAmbassadorHostSource creates a new ambassadorHostSource with the given config.
@@ -67,6 +69,8 @@ func NewAmbassadorHostSource(
 	dynamicKubeClient dynamic.Interface,
 	kubeClient kubernetes.Interface,
 	namespace string,
+	annotationFilter string,
+	labelSelector labels.Selector,
 ) (Source, error) {
 	var err error
 
@@ -85,6 +89,7 @@ func NewAmbassadorHostSource(
 
 	informerFactory.Start(ctx.Done())
 
+	// wait for the local cache to be populated.
 	if err := waitForDynamicCacheSync(context.Background(), informerFactory); err != nil {
 		return nil, err
 	}
@@ -98,20 +103,23 @@ func NewAmbassadorHostSource(
 		dynamicKubeClient:      dynamicKubeClient,
 		kubeClient:             kubeClient,
 		namespace:              namespace,
+		annotationFilter:       annotationFilter,
 		ambassadorHostInformer: ambassadorHostInformer,
 		unstructuredConverter:  uc,
+		labelSelector:          labelSelector,
 	}, nil
 }
 
 // Endpoints returns endpoint objects for each host-target combination that should be processed.
 // Retrieves all Hosts in the source's namespace(s).
 func (sc *ambassadorHostSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, error) {
-	hosts, err := sc.ambassadorHostInformer.Lister().ByNamespace(sc.namespace).List(labels.Everything())
+	hosts, err := sc.ambassadorHostInformer.Lister().ByNamespace(sc.namespace).List(sc.labelSelector)
 	if err != nil {
 		return nil, err
 	}
 
-	endpoints := []*endpoint.Endpoint{}
+	// Get a list of Ambassador Host resources
+	ambassadorHosts := []*ambassador.Host{}
 	for _, hostObj := range hosts {
 		unstructuredHost, ok := hostObj.(*unstructured.Unstructured)
 		if !ok {
@@ -123,7 +131,18 @@ func (sc *ambassadorHostSource) Endpoints(ctx context.Context) ([]*endpoint.Endp
 		if err != nil {
 			return nil, err
 		}
+		ambassadorHosts = append(ambassadorHosts, host)
+	}
+
+	// Filter Ambassador Hosts
+	ambassadorHosts, err = sc.filterByAnnotations(ambassadorHosts)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to filter Ambassador Hosts by annotation")
+	}
 
+	endpoints := []*endpoint.Endpoint{}
+
+	for _, host := range ambassadorHosts {
 		fullname := fmt.Sprintf("%s/%s", host.Namespace, host.Name)
 
 		// look for the "exernal-dns.ambassador-service" annotation. If it is not there then just ignore this `Host`
@@ -272,3 +291,35 @@ func newUnstructuredConverter() (*unstructuredConverter, error) {
 
 	return uc, nil
 }
+
+// Filter a list of Ambassador Host Resources to only return the ones that
+// contain the required External-DNS annotation filter
+func (sc *ambassadorHostSource) filterByAnnotations(ambassadorHosts []*ambassador.Host) ([]*ambassador.Host, error) {
+	// External-DNS Annotation Filter
+	labelSelector, err := metav1.ParseToLabelSelector(sc.annotationFilter)
+	if err != nil {
+		return nil, err
+	}
+
+	selector, err := metav1.LabelSelectorAsSelector(labelSelector)
+	if err != nil {
+		return nil, err
+	}
+
+	// empty filter returns original list of Ambassador Hosts
+	if selector.Empty() {
+		return ambassadorHosts, nil
+	}
+
+	// Return a filtered list of Ambassador Hosts
+	filteredList := []*ambassador.Host{}
+	for _, host := range ambassadorHosts {
+		annotations := labels.Set(host.Annotations)
+		// include Ambassador Host if its annotations match the annotation filter
+		if selector.Matches(annotations) {
+			filteredList = append(filteredList, host)
+		}
+	}
+
+	return filteredList, nil
+}