feat: resolve dns targets in ingress based records to create A/AAAA instead of CNAME

docs/sources/ingress.md

@@ -46,3 +46,6 @@ the values from that.
 
 2. Otherwise, iterates over the Ingress's `status.loadBalancer.ingress`, 
 adding each non-empty `ip` and `hostname`. 
+
+In the case that `--resolve-ingress-target-hostname` set, it will resolve hostnames in the status to create 
+A/AAAA records instead of CNAME.

main.go

@@ -156,6 +156,7 @@ func main() {
 		OCPRouterName:                  cfg.OCPRouterName,
 		UpdateEvents:                   cfg.UpdateEvents,
 		ResolveLoadBalancerHostname:    cfg.ResolveServiceLoadBalancerHostname,
+		ResolveIngressTargetHostname:   cfg.ResolveIngressTargetHostname,
 		TraefikDisableLegacy:           cfg.TraefikDisableLegacy,
 		TraefikDisableNew:              cfg.TraefikDisableNew,
 	}

pkg/apis/externaldns/types.go

@@ -178,6 +178,7 @@ type Config struct {
 	CFUsername                         string
 	CFPassword                         string
 	ResolveServiceLoadBalancerHostname bool
+	ResolveIngressTargetHostname       bool
 	RFC2136Host                        string
 	RFC2136Port                        int
 	RFC2136Zone                        []string
@@ -431,6 +432,7 @@ func (cfg *Config) ParseFlags(args []string) error {
 	app.Flag("kubeconfig", "Retrieve target cluster configuration from a Kubernetes configuration file (default: auto-detect)").Default(defaultConfig.KubeConfig).StringVar(&cfg.KubeConfig)
 	app.Flag("request-timeout", "Request timeout when calling Kubernetes APIs. 0s means no timeout").Default(defaultConfig.RequestTimeout.String()).DurationVar(&cfg.RequestTimeout)
 	app.Flag("resolve-service-load-balancer-hostname", "Resolve the hostname of LoadBalancer-type Service object to IP addresses in order to create DNS A/AAAA records instead of CNAMEs").BoolVar(&cfg.ResolveServiceLoadBalancerHostname)
+	app.Flag("resolve-ingress-target-hostname", "Resolve the hostname of Ingress target to IP addresses in order to create DNS A/AAAA records instead of CNAMEs").BoolVar(&cfg.ResolveIngressTargetHostname)
 
 	// Flags related to cloud foundry
 	app.Flag("cf-api-endpoint", "The fully-qualified domain name of the cloud foundry instance you are targeting").Default(defaultConfig.CFAPIEndpoint).StringVar(&cfg.CFAPIEndpoint)

source/ingress.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"net"
 	"sort"
 	"strings"
 	"text/template"
@@ -54,21 +55,22 @@ const (
 // Use targetAnnotationKey to explicitly set Endpoint. (useful if the ingress
 // controller does not update, or to override with alternative endpoint)
 type ingressSource struct {
-	client                   kubernetes.Interface
-	namespace                string
-	annotationFilter         string
-	ingressClassNames        []string
-	fqdnTemplate             *template.Template
-	combineFQDNAnnotation    bool
-	ignoreHostnameAnnotation bool
-	ingressInformer          netinformers.IngressInformer
-	ignoreIngressTLSSpec     bool
-	ignoreIngressRulesSpec   bool
-	labelSelector            labels.Selector
+	client                       kubernetes.Interface
+	namespace                    string
+	annotationFilter             string
+	ingressClassNames            []string
+	fqdnTemplate                 *template.Template
+	combineFQDNAnnotation        bool
+	ignoreHostnameAnnotation     bool
+	ingressInformer              netinformers.IngressInformer
+	ignoreIngressTLSSpec         bool
+	ignoreIngressRulesSpec       bool
+	labelSelector                labels.Selector
+	resolveIngressTargetHostname bool
 }
 
 // NewIngressSource creates a new ingressSource with the given config.
-func NewIngressSource(ctx context.Context, kubeClient kubernetes.Interface, namespace, annotationFilter string, fqdnTemplate string, combineFqdnAnnotation bool, ignoreHostnameAnnotation bool, ignoreIngressTLSSpec bool, ignoreIngressRulesSpec bool, labelSelector labels.Selector, ingressClassNames []string) (Source, error) {
+func NewIngressSource(ctx context.Context, kubeClient kubernetes.Interface, namespace, annotationFilter string, fqdnTemplate string, combineFqdnAnnotation bool, ignoreHostnameAnnotation bool, ignoreIngressTLSSpec bool, ignoreIngressRulesSpec bool, labelSelector labels.Selector, ingressClassNames []string, resolveIngressTargetHostname bool) (Source, error) {
 	tmpl, err := parseTemplate(fqdnTemplate)
 	if err != nil {
 		return nil, err
@@ -110,17 +112,18 @@ func NewIngressSource(ctx context.Context, kubeClient kubernetes.Interface, name
 	}
 
 	sc := &ingressSource{
-		client:                   kubeClient,
-		namespace:                namespace,
-		annotationFilter:         annotationFilter,
-		ingressClassNames:        ingressClassNames,
-		fqdnTemplate:             tmpl,
-		combineFQDNAnnotation:    combineFqdnAnnotation,
-		ignoreHostnameAnnotation: ignoreHostnameAnnotation,
-		ingressInformer:          ingressInformer,
-		ignoreIngressTLSSpec:     ignoreIngressTLSSpec,
-		ignoreIngressRulesSpec:   ignoreIngressRulesSpec,
-		labelSelector:            labelSelector,
+		client:                       kubeClient,
+		namespace:                    namespace,
+		annotationFilter:             annotationFilter,
+		ingressClassNames:            ingressClassNames,
+		fqdnTemplate:                 tmpl,
+		combineFQDNAnnotation:        combineFqdnAnnotation,
+		ignoreHostnameAnnotation:     ignoreHostnameAnnotation,
+		ingressInformer:              ingressInformer,
+		ignoreIngressTLSSpec:         ignoreIngressTLSSpec,
+		ignoreIngressRulesSpec:       ignoreIngressRulesSpec,
+		labelSelector:                labelSelector,
+		resolveIngressTargetHostname: resolveIngressTargetHostname,
 	}
 	return sc, nil
 }
@@ -153,7 +156,7 @@ func (sc *ingressSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, e
 			continue
 		}
 
-		ingEndpoints := endpointsFromIngress(ing, sc.ignoreHostnameAnnotation, sc.ignoreIngressTLSSpec, sc.ignoreIngressRulesSpec)
+		ingEndpoints := endpointsFromIngress(ing, sc.ignoreHostnameAnnotation, sc.ignoreIngressTLSSpec, sc.ignoreIngressRulesSpec, sc.resolveIngressTargetHostname)
 
 		// apply template if host is missing on ingress
 		if (sc.combineFQDNAnnotation || len(ingEndpoints) == 0) && sc.fqdnTemplate != nil {
@@ -194,7 +197,7 @@ func (sc *ingressSource) endpointsFromTemplate(ing *networkv1.Ingress) ([]*endpo
 
 	targets := getTargetsFromTargetAnnotation(ing.Annotations)
 	if len(targets) == 0 {
-		targets = targetsFromIngressStatus(ing.Status)
+		targets = targetsFromIngressStatus(ing.Status, sc.resolveIngressTargetHostname)
 	}
 
 	providerSpecific, setIdentifier := getProviderSpecificAnnotations(ing.Annotations)
@@ -285,15 +288,15 @@ func (sc *ingressSource) setDualstackLabel(ingress *networkv1.Ingress, endpoints
 }
 
 // endpointsFromIngress extracts the endpoints from ingress object
-func endpointsFromIngress(ing *networkv1.Ingress, ignoreHostnameAnnotation bool, ignoreIngressTLSSpec bool, ignoreIngressRulesSpec bool) []*endpoint.Endpoint {
+func endpointsFromIngress(ing *networkv1.Ingress, ignoreHostnameAnnotation bool, ignoreIngressTLSSpec bool, ignoreIngressRulesSpec bool, resolveIngressTargetHostname bool) []*endpoint.Endpoint {
 	resource := fmt.Sprintf("ingress/%s/%s", ing.Namespace, ing.Name)
 
 	ttl := getTTLFromAnnotations(ing.Annotations, resource)
 
 	targets := getTargetsFromTargetAnnotation(ing.Annotations)
 
 	if len(targets) == 0 {
-		targets = targetsFromIngressStatus(ing.Status)
+		targets = targetsFromIngressStatus(ing.Status, resolveIngressTargetHostname)
 	}
 
 	providerSpecific, setIdentifier := getProviderSpecificAnnotations(ing.Annotations)
@@ -347,15 +350,26 @@ func endpointsFromIngress(ing *networkv1.Ingress, ignoreHostnameAnnotation bool,
 	return endpoints
 }
 
-func targetsFromIngressStatus(status networkv1.IngressStatus) endpoint.Targets {
+func targetsFromIngressStatus(status networkv1.IngressStatus, resolveIngressTargetHostname bool) endpoint.Targets {
 	var targets endpoint.Targets
 
 	for _, lb := range status.LoadBalancer.Ingress {
 		if lb.IP != "" {
 			targets = append(targets, lb.IP)
 		}
 		if lb.Hostname != "" {
-			targets = append(targets, lb.Hostname)
+			if resolveIngressTargetHostname {
+				ips, err := net.LookupIP(lb.Hostname)
+				if err != nil {
+					log.Errorf("Unable to resolve %q: %v", lb.Hostname, err)
+					continue
+				}
+				for _, ip := range ips {
+					targets = append(targets, ip.String())
+				}
+			} else {
+				targets = append(targets, lb.Hostname)
+			}
 		}
 	}
 

source/ingress_test.go

@@ -66,6 +66,7 @@ func (suite *IngressSuite) SetupTest() {
 		false,
 		labels.Everything(),
 		[]string{},
+		false,
 	)
 	suite.NoError(err, "should initialize ingress source")
 }
@@ -103,6 +104,7 @@ func TestNewIngressSource(t *testing.T) {
 		combineFQDNAndAnnotation bool
 		expectError              bool
 		ingressClassNames        []string
+		resolveIngress           bool
 	}{
 		{
 			title:        "invalid template",
@@ -162,6 +164,7 @@ func TestNewIngressSource(t *testing.T) {
 				false,
 				labels.Everything(),
 				ti.ingressClassNames,
+				ti.resolveIngress,
 			)
 			if ti.expectError {
 				assert.Error(t, err)
@@ -182,6 +185,7 @@ func testEndpointsFromIngress(t *testing.T) {
 		ignoreIngressTLSSpec     bool
 		ignoreIngressRulesSpec   bool
 		expected                 []*endpoint.Endpoint
+		resolveIngress           bool
 	}{
 		{
 			title: "one rule.host one lb.hostname",
@@ -267,14 +271,33 @@ func testEndpointsFromIngress(t *testing.T) {
 		{
 			title: "invalid hostname does not generate endpoints",
 			ingress: fakeIngress{
-				dnsnames:  []string{"this-is-an-exceedingly-long-label-that-external-dns-should-reject.example.org"},
+				dnsnames: []string{"this-is-an-exceedingly-long-label-that-external-dns-should-reject.example.org"},
 			},
 			expected: []*endpoint.Endpoint{},
+		}, {
+			title:          "one rule.host one lb.hostname with resolve true",
+			resolveIngress: true,
+			ingress: fakeIngress{
+				dnsnames:  []string{"foo.bar"},
+				hostnames: []string{"example.org"}, // Use a resolvable hostname for testing.
+			},
+			expected: []*endpoint.Endpoint{
+				{
+					DNSName:    "foo.bar",
+					RecordType: endpoint.RecordTypeA,
+					Targets:    endpoint.Targets{"93.184.216.34"},
+				},
+				{
+					DNSName:    "foo.bar",
+					RecordType: endpoint.RecordTypeAAAA,
+					Targets:    endpoint.Targets{"2606:2800:220:1:248:1893:25c8:1946"},
+				},
+			},
 		},
 	} {
 		t.Run(ti.title, func(t *testing.T) {
 			realIngress := ti.ingress.Ingress()
-			validateEndpoints(t, endpointsFromIngress(realIngress, ti.ignoreHostnameAnnotation, ti.ignoreIngressTLSSpec, ti.ignoreIngressRulesSpec), ti.expected)
+			validateEndpoints(t, endpointsFromIngress(realIngress, ti.ignoreHostnameAnnotation, ti.ignoreIngressTLSSpec, ti.ignoreIngressRulesSpec, ti.resolveIngress), ti.expected)
 		})
 	}
 }
@@ -373,7 +396,7 @@ func testEndpointsFromIngressHostnameSourceAnnotation(t *testing.T) {
 	} {
 		t.Run(ti.title, func(t *testing.T) {
 			realIngress := ti.ingress.Ingress()
-			validateEndpoints(t, endpointsFromIngress(realIngress, false, false, false), ti.expected)
+			validateEndpoints(t, endpointsFromIngress(realIngress, false, false, false, false), ti.expected)
 		})
 	}
 }
@@ -396,6 +419,7 @@ func testIngressEndpoints(t *testing.T) {
 		ignoreIngressRulesSpec   bool
 		ingressLabelSelector     labels.Selector
 		ingressClassNames        []string
+		resolveIngress           bool
 	}{
 		{
 			title:           "no ingress",
@@ -1388,6 +1412,31 @@ func testIngressEndpoints(t *testing.T) {
 			},
 			expected: []*endpoint.Endpoint{},
 		},
+		{
+			title:           "simple ingress with resolving",
+			resolveIngress:  true,
+			targetNamespace: "",
+			ingressItems: []fakeIngress{
+				{
+					name:      "fake-with-resolv1",
+					namespace: namespace,
+					dnsnames:  []string{"foo.bar"},
+					hostnames: []string{"example.org"}, // Use a resolvable hostname for testing.
+				},
+			},
+			expected: []*endpoint.Endpoint{
+				{
+					DNSName:    "foo.bar",
+					RecordType: endpoint.RecordTypeA,
+					Targets:    endpoint.Targets{"93.184.216.34"},
+				},
+				{
+					DNSName:    "foo.bar",
+					RecordType: endpoint.RecordTypeAAAA,
+					Targets:    endpoint.Targets{"2606:2800:220:1:248:1893:25c8:1946"},
+				},
+			},
+		},
 	} {
 		ti := ti
 		t.Run(ti.title, func(t *testing.T) {
@@ -1416,6 +1465,7 @@ func testIngressEndpoints(t *testing.T) {
 				ti.ignoreIngressRulesSpec,
 				ti.ingressLabelSelector,
 				ti.ingressClassNames,
+				ti.resolveIngress,
 			)
 			// Informer cache has all of the ingresses. Retrieve and validate their endpoints.
 			res, err := source.Endpoints(context.Background())

source/store.go

@@ -74,6 +74,7 @@ type Config struct {
 	OCPRouterName                  string
 	UpdateEvents                   bool
 	ResolveLoadBalancerHostname    bool
+	ResolveIngressTargetHostname   bool
 	TraefikDisableLegacy           bool
 	TraefikDisableNew              bool
 }
@@ -224,7 +225,7 @@ func BuildWithConfig(ctx context.Context, source string, p ClientGenerator, cfg
 		if err != nil {
 			return nil, err
 		}
-		return NewIngressSource(ctx, client, cfg.Namespace, cfg.AnnotationFilter, cfg.FQDNTemplate, cfg.CombineFQDNAndAnnotation, cfg.IgnoreHostnameAnnotation, cfg.IgnoreIngressTLSSpec, cfg.IgnoreIngressRulesSpec, cfg.LabelFilter, cfg.IngressClassNames)
+		return NewIngressSource(ctx, client, cfg.Namespace, cfg.AnnotationFilter, cfg.FQDNTemplate, cfg.CombineFQDNAndAnnotation, cfg.IgnoreHostnameAnnotation, cfg.IgnoreIngressTLSSpec, cfg.IgnoreIngressRulesSpec, cfg.LabelFilter, cfg.IngressClassNames, cfg.ResolveLoadBalancerHostname)
 	case "pod":
 		client, err := p.KubeClient()
 		if err != nil {