From 44fd8105370f268bf7eb8808427b94098efcc1ba Mon Sep 17 00:00:00 2001
From: Peter Honeder <peter.honeder@gmail.com>
Date: Mon, 21 Nov 2022 11:49:16 +0100
Subject: [PATCH] feat: allow pod IPs even for non-hostNetwork pods, but only
 for the internalHostnameAnnotationKey which doesn't use the node's IP anyway

---
 source/pod.go      | 54 ++++++++++++++++++++++------------------------
 source/pod_test.go |  2 +-
 2 files changed, 27 insertions(+), 29 deletions(-)

diff --git a/source/pod.go b/source/pod.go
index 36e6ffe50e..c6d781809f 100644
--- a/source/pod.go
+++ b/source/pod.go
@@ -21,7 +21,6 @@ import (
 
 	"sigs.k8s.io/external-dns/endpoint"
 
-	log "github.com/sirupsen/logrus"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/labels"
 	kubeinformers "k8s.io/client-go/informers"
@@ -84,11 +83,7 @@ func (ps *podSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, error
 
 	domains := make(map[string][]string)
 	for _, pod := range pods {
-		if !pod.Spec.HostNetwork {
-			log.Debugf("skipping pod %s. hostNetwork=false", pod.Name)
-			continue
-		}
-
+		// accept hostname annotations that point to the pod's IP, no matter if the pod spec uses the host network
 		if domain, ok := pod.Annotations[internalHostnameAnnotationKey]; ok {
 			if _, ok := domains[domain]; !ok {
 				domains[domain] = []string{}
@@ -96,28 +91,9 @@ func (ps *podSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, error
 			domains[domain] = append(domains[domain], pod.Status.PodIP)
 		}
 
-		if domain, ok := pod.Annotations[hostnameAnnotationKey]; ok {
-			if _, ok := domains[domain]; !ok {
-				domains[domain] = []string{}
-			}
-
-			node, _ := ps.nodeInformer.Lister().Get(pod.Spec.NodeName)
-			for _, address := range node.Status.Addresses {
-				if address.Type == corev1.NodeExternalIP {
-					domains[domain] = append(domains[domain], address.Address)
-				}
-			}
-		}
-
-		if ps.compatibility == "kops-dns-controller" {
-			if domain, ok := pod.Annotations[kopsDNSControllerInternalHostnameAnnotationKey]; ok {
-				if _, ok := domains[domain]; !ok {
-					domains[domain] = []string{}
-				}
-				domains[domain] = append(domains[domain], pod.Status.PodIP)
-			}
-
-			if domain, ok := pod.Annotations[kopsDNSControllerHostnameAnnotationKey]; ok {
+		// accept annotations that point to the node's external IP only for pods using the host network
+		if pod.Spec.HostNetwork {
+			if domain, ok := pod.Annotations[hostnameAnnotationKey]; ok {
 				if _, ok := domains[domain]; !ok {
 					domains[domain] = []string{}
 				}
@@ -129,6 +105,28 @@ func (ps *podSource) Endpoints(ctx context.Context) ([]*endpoint.Endpoint, error
 					}
 				}
 			}
+
+			if ps.compatibility == "kops-dns-controller" {
+				if domain, ok := pod.Annotations[kopsDNSControllerInternalHostnameAnnotationKey]; ok {
+					if _, ok := domains[domain]; !ok {
+						domains[domain] = []string{}
+					}
+					domains[domain] = append(domains[domain], pod.Status.PodIP)
+				}
+
+				if domain, ok := pod.Annotations[kopsDNSControllerHostnameAnnotationKey]; ok {
+					if _, ok := domains[domain]; !ok {
+						domains[domain] = []string{}
+					}
+
+					node, _ := ps.nodeInformer.Lister().Get(pod.Spec.NodeName)
+					for _, address := range node.Status.Addresses {
+						if address.Type == corev1.NodeExternalIP {
+							domains[domain] = append(domains[domain], address.Address)
+						}
+					}
+				}
+			}
 		}
 	}
 	endpoints := []*endpoint.Endpoint{}
diff --git a/source/pod_test.go b/source/pod_test.go
index c138aaf5fd..6d8850e205 100644
--- a/source/pod_test.go
+++ b/source/pod_test.go
@@ -254,7 +254,7 @@ func TestPodSource(t *testing.T) {
 			"",
 			[]*endpoint.Endpoint{
 				{DNSName: "a.foo.example.org", Targets: endpoint.Targets{"54.10.11.1"}, RecordType: endpoint.RecordTypeA},
-				{DNSName: "internal.a.foo.example.org", Targets: endpoint.Targets{"10.0.1.1"}, RecordType: endpoint.RecordTypeA},
+				{DNSName: "internal.a.foo.example.org", Targets: endpoint.Targets{"10.0.1.1", "100.0.1.2"}, RecordType: endpoint.RecordTypeA},
 			},
 			false,
 			[]*corev1.Node{