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fix(endpoint): ensure trailing dot to target as required by RFC 2782 #5534

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k8s-ci-robot merged 1 commit into from
Nov 21, 2025
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fix(endpoint): ensure trailing dot to target as required by RFC 2782 #5534

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13 changes: 9 additions & 4 deletions endpoint/endpoint.go
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Original file line number Diff line number Diff line change
Expand Up @@ -260,8 +260,9 @@ func NewEndpointWithTTL(dnsName, recordType string, ttl TTL, targets ...string)
for idx, target := range targets {
// Only trim trailing dots for domain name record types, not for TXT or NAPTR records
// TXT records can contain arbitrary text including multiple dots
// SRV can contain dots in their target part (RFC2782)
switch recordType {
case RecordTypeTXT, RecordTypeNAPTR:
case RecordTypeTXT, RecordTypeNAPTR, RecordTypeSRV:
cleanTargets[idx] = target
default:
cleanTargets[idx] = strings.TrimSuffix(target, ".")
Expand Down Expand Up @@ -484,11 +485,15 @@ func (t Targets) ValidateMXRecord() bool {

func (t Targets) ValidateSRVRecord() bool {
for _, target := range t {
// SRV records must have a priority, weight, and port value, e.g. "10 5 5060 example.com"
// as per https://www.rfc-editor.org/rfc/rfc2782.txt
// SRV records must have a priority, weight, a port value and a target e.g. "10 5 5060 example.com."
// as per https://www.rfc-editor.org/rfc/rfc2782.txt the target host has to end with a dot.
targetParts := strings.Fields(strings.TrimSpace(target))
if len(targetParts) != 4 {
log.Debugf("Invalid SRV record target: %s. SRV records must have a priority, weight, and port value, e.g. '10 5 5060 example.com'", target)
log.Debugf("Invalid SRV record target: %s. SRV records must have a priority, weight, a port value and a target host, e.g. '10 5 5060 example.com.'", target)
return false
}
if !strings.HasSuffix(targetParts[3], ".") {
log.Debugf("Invalid SRV record target: %s. Target host does not end with a dot.'", target)
return false
}

Expand Down
17 changes: 13 additions & 4 deletions endpoint/endpoint_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -787,7 +787,7 @@ func TestPDNScheckEndpoint(t *testing.T) {
endpoint: Endpoint{
DNSName: "_service._tls.example.com",
RecordType: RecordTypeSRV,
Targets: Targets{"10 20 5060 service.example.com"},
Targets: Targets{"10 20 5060 service.example.com."},
},
expected: true,
},
Expand All @@ -805,7 +805,16 @@ func TestPDNScheckEndpoint(t *testing.T) {
endpoint: Endpoint{
DNSName: "_service._tls.example.com",
RecordType: RecordTypeSRV,
Targets: Targets{"10 20 abc service.example.com"},
Targets: Targets{"10 20 abc service.example.com."},
},
expected: false,
},
{
description: "Invalid SRV record with missing dot for target host",
endpoint: Endpoint{
DNSName: "_service._tls.example.com",
RecordType: RecordTypeSRV,
Targets: Targets{"10 20 5060 service.example.com"},
},
expected: false,
},
Expand Down Expand Up @@ -895,7 +904,7 @@ func TestCheckEndpoint(t *testing.T) {
endpoint: Endpoint{
DNSName: "_service._tcp.example.com",
RecordType: RecordTypeSRV,
Targets: Targets{"10 5 5060 example.com"},
Targets: Targets{"10 5 5060 example.com."},
},
expected: true,
},
Expand All @@ -904,7 +913,7 @@ func TestCheckEndpoint(t *testing.T) {
endpoint: Endpoint{
DNSName: "_service._tcp.example.com",
RecordType: RecordTypeSRV,
Targets: Targets{"10 5 example.com"},
Targets: Targets{"10 5 example.com."},
},
expected: false,
},
Expand Down
3 changes: 2 additions & 1 deletion source/service.go
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Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@ import (
"k8s.io/client-go/kubernetes"
"k8s.io/client-go/tools/cache"

"sigs.k8s.io/external-dns/provider"
"sigs.k8s.io/external-dns/source/informers"

"sigs.k8s.io/external-dns/source/annotations"
Expand Down Expand Up @@ -855,7 +856,7 @@ func (sc *serviceSource) extractNodePortEndpoints(svc *v1.Service, hostname stri
// see https://en.wikipedia.org/wiki/SRV_record

// build a target with a priority of 0, weight of 50, and pointing the given port on the given host
target := fmt.Sprintf("0 50 %d %s", port.NodePort, hostname)
target := fmt.Sprintf("0 50 %d %s", port.NodePort, provider.EnsureTrailingDot(hostname))
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@ivankatliarchuk ivankatliarchuk Sep 20, 2025 •
edited
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Can we have a struct similar to

external-dns/endpoint/endpoint.go

Line 78 in f779395

type MXTarget struct {

so we do target := NewSRVRecord()

And importing provider libraries in sources may lead to potential circular dependencies.

We may better move EnsureTrailingDot to endpoint package, in this or follow-up PR.

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@frittentheke frittentheke Nov 10, 2025

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Once there is a working PR in regards to the RFC 2782 issue, I gladly add another commit moving the EnsureTrailingDot function to endpoint.


// take the service name from the K8s Service object
// it is safe to use since it is DNS compatible
Expand Down
20 changes: 10 additions & 10 deletions source/service_fqdn_test.go
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Expand Up @@ -412,7 +412,7 @@ func TestServiceSourceFqdnTemplatingExamples(t *testing.T) {
},
},
},
fqdnTemplate: `{{ $name := .Name }}{{ range .Spec.Ports -}}{{ $name }}{{ if eq .Name "http2" }}.http2{{ else if eq .Name "debug" }}.debug{{ end }}.example.tld{{printf "," }}{{ end }}`,
fqdnTemplate: `{{ $name := .Name }}{{ range .Spec.Ports -}}{{ $name }}{{ if eq .Name "http2" }}.http2{{ else if eq .Name "debug" }}.debug{{ end }}.example.tld.{{printf "," }}{{ end }}`,
expected: []*endpoint.Endpoint{
// TODO: This test shows that there is a bug that needs to be fixed in the external-dns logic.
{DNSName: "", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"192.51.100.22", "192.51.100.5"}},
Expand Down Expand Up @@ -736,15 +736,15 @@ func TestServiceSourceFqdnTemplatingExamples(t *testing.T) {
expected: []*endpoint.Endpoint{
// TODO: This test shows that there is a bug that needs to be fixed in the external-dns logic. Not a critical issue, as will be filtered out by the source.
{DNSName: "", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"10.96.41.132", "203.0.113.10"}},
{DNSName: "_service-one._tcp", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30080 ", "0 50 30082 "}}, // TODO: wrong SRV target format
{DNSName: "_service-one._tcp.debug.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30080 debug.host.tld", "0 50 30082 debug.host.tld"}},
{DNSName: "_service-one._tcp.http.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30080 http.host.tld", "0 50 30082 http.host.tld"}},
{DNSName: "_service-three._tcp", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 25565 "}}, // TODO: wrong SRV target format
{DNSName: "_service-three._tcp.debug.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 25565 debug.host.tld"}},
{DNSName: "_service-three._tcp.minecraft.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 25565 minecraft.host.tld"}},
{DNSName: "_service-three._udp", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30083 "}}, // TODO: wrong SRV target format
{DNSName: "_service-three._udp.debug.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30083 debug.host.tld"}},
{DNSName: "_service-three._udp.minecraft.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30083 minecraft.host.tld"}},
{DNSName: "_service-one._tcp", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30080 .", "0 50 30082 ."}}, // TODO: wrong SRV target format
{DNSName: "_service-one._tcp.debug.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30080 debug.host.tld.", "0 50 30082 debug.host.tld."}},
{DNSName: "_service-one._tcp.http.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30080 http.host.tld.", "0 50 30082 http.host.tld."}},
{DNSName: "_service-three._tcp", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 25565 ."}}, // TODO: wrong SRV target format
{DNSName: "_service-three._tcp.debug.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 25565 debug.host.tld."}},
{DNSName: "_service-three._tcp.minecraft.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 25565 minecraft.host.tld."}},
{DNSName: "_service-three._udp", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30083 ."}}, // TODO: wrong SRV target format
{DNSName: "_service-three._udp.debug.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30083 debug.host.tld."}},
{DNSName: "_service-three._udp.minecraft.host.tld", RecordType: endpoint.RecordTypeSRV, Targets: endpoint.Targets{"0 50 30083 minecraft.host.tld."}},
{DNSName: "debug.host.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"203.0.113.10"}},
{DNSName: "http.host.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"203.0.113.10"}},
{DNSName: "minecraft.host.tld", RecordType: endpoint.RecordTypeA, Targets: endpoint.Targets{"203.0.113.10"}},
Expand Down
20 changes: 10 additions & 10 deletions source/service_test.go
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Expand Up @@ -1741,7 +1741,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.HostnameKey: "foo.example.org.",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.1", "54.10.11.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::1", "2001:DB8::3"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -1816,7 +1816,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
svcTrafficPolicy: v1.ServiceExternalTrafficPolicyTypeCluster,
fqdnTemplate: "{{.Name}}.bar.example.com",
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.bar.example.com", Targets: endpoint.Targets{"0 50 30192 foo.bar.example.com"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.bar.example.com", Targets: endpoint.Targets{"0 50 30192 foo.bar.example.com."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.bar.example.com", Targets: endpoint.Targets{"54.10.11.1", "54.10.11.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.bar.example.com", Targets: endpoint.Targets{"2001:DB8::1", "2001:DB8::3"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -1856,7 +1856,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.HostnameKey: "foo.example.org.",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"10.0.1.1", "10.0.1.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::1", "2001:DB8::2"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -1892,7 +1892,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.HostnameKey: "foo.example.org.",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::3"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -1938,7 +1938,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.HostnameKey: "foo.example.org.",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::3"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -1987,7 +1987,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.HostnameKey: "foo.example.org.",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.1"}, RecordType: endpoint.RecordTypeA},
},
nodes: []*v1.Node{{
Expand Down Expand Up @@ -2031,7 +2031,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.HostnameKey: "foo.example.org.",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.1"}, RecordType: endpoint.RecordTypeA},
},
nodes: []*v1.Node{{
Expand Down Expand Up @@ -2087,7 +2087,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.AccessKey: "private",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"10.0.1.1", "10.0.1.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::1", "2001:DB8::2"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -2127,7 +2127,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
annotations.AccessKey: "public",
},
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.1", "54.10.11.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::1", "2001:DB8::3"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down Expand Up @@ -2170,7 +2170,7 @@ func TestServiceSourceNodePortServices(t *testing.T) {
},
exposeInternalIPv6: true,
expected: []*endpoint.Endpoint{
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org"}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "_foo._tcp.foo.example.org", Targets: endpoint.Targets{"0 50 30192 foo.example.org."}, RecordType: endpoint.RecordTypeSRV},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"54.10.11.1", "54.10.11.2"}, RecordType: endpoint.RecordTypeA},
{DNSName: "foo.example.org", Targets: endpoint.Targets{"2001:DB8::1", "2001:DB8::2", "2001:DB8::3", "2001:DB8::4"}, RecordType: endpoint.RecordTypeAAAA},
},
Expand Down
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