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feat(annotations): Support multiple annotation prefixes #6449

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c1e58a2
feat(source): set transformer on all informers
vflaux May 21, 2026
621450a
feat(annotations): support multiple annotation prefixes
vflaux May 19, 2026
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8 changes: 5 additions & 3 deletions controller/execute.go
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,8 @@ import (
"net/http"
"os"
"os/signal"
"slices"
"strings"
"syscall"
"time"

Expand Down Expand Up @@ -63,9 +65,9 @@ func execute(ctx context.Context) {
}

// Set annotation prefix (required since init() was removed)
annotations.SetAnnotationPrefix(cfg.AnnotationPrefix)
if cfg.AnnotationPrefix != annotations.DefaultAnnotationPrefix {
log.Infof("Using custom annotation prefix: %s", cfg.AnnotationPrefix)
annotations.SetAnnotationPrefixes(cfg.AnnotationPrefixes...)
if !slices.Equal(cfg.AnnotationPrefixes, []string{annotations.DefaultAnnotationPrefix, annotations.AlphaAnnotationPrefix}) {
log.Infof("Using custom annotation prefixes: %s", strings.Join(cfg.AnnotationPrefixes, ","))
}

if err := configureLogger(cfg); err != nil {
Expand Down
6 changes: 6 additions & 0 deletions docs/annotations/annotations.md
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Expand Up @@ -29,6 +29,12 @@ The following table documents which sources support which annotations:
[^4]: For Gateway API sources, annotation placement differs by type. See [Gateway API Annotation Placement](#gateway-api-annotation-placement) for details.
[^5]: The annotation must be on the listener's `VirtualService`.

Annotation prefixes can be configured with the `--annotation-prefix` flag, the default prefixes are `external-dns.kubernetes.io/` and `external-dns.alpha.kubernetes.io/` (for backward compatibility).

!!!note "Annotation prefix deprecation"
The `external-dns.alpha.kubernetes.io/` prefix is deprecated and will eventually be removed. It is recommended to use the `external-dns.kubernetes.io/` prefix for all annotations.
For example, `external-dns.alpha.kubernetes.io/hostname` should be updated to `external-dns.kubernetes.io/hostname`.

## external-dns.kubernetes.io/access

Specifies which set of node IP addresses to use for a `Service` of type `NodePort`.
Expand Down
2 changes: 1 addition & 1 deletion docs/flags.md
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Expand Up @@ -20,7 +20,7 @@ tags:
| `--skipper-routegroup-groupversion="zalando.org/v1"` | The resource version for skipper routegroup |
| `--[no-]always-publish-not-ready-addresses` | Always publish also not ready addresses for headless services (optional) |
| `--annotation-filter=""` | Filter resources queried for endpoints by annotation, using label selector semantics |
| `--annotation-prefix="external-dns.kubernetes.io/"` | Annotation prefix for external-dns annotations (default: external-dns.kubernetes.io/) |
| `--annotation-prefix=external-dns.kubernetes.io/...` | Annotation prefix for external-dns annotations (default: external-dns.kubernetes.io/, ); specify multiple times to support additional prefixes |
| `--compatibility=` | Process annotation semantics from legacy implementations (optional, options: mate, molecule, kops-dns-controller) |
| `--connector-source-server="localhost:8080"` | The server to connect for connector source, valid only when using connector source |
| `--crd-source-apiversion="externaldns.k8s.io/v1alpha1"` | API version of the CRD for crd source, e.g. `externaldns.k8s.io/v1alpha1`, valid only when using crd source |
Expand Down
1 change: 1 addition & 0 deletions internal/flags/binders.go
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Expand Up @@ -77,6 +77,7 @@ func (b *KingpinBinder) Int64Var(name, help string, def int64, target *int64) {
}

func (b *KingpinBinder) StringsVar(name, help string, def []string, target *[]string) {
*target = nil
if len(def) > 0 {
b.App.Flag(name, help).Default(def...).StringsVar(target)
return
Expand Down
10 changes: 5 additions & 5 deletions pkg/apis/externaldns/types.go
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Expand Up @@ -56,7 +56,7 @@ type Config struct {
Sources []string
Namespace string
AnnotationFilter string
AnnotationPrefix string
AnnotationPrefixes []string
LabelFilter string
IngressClassNames []string
FQDNTemplate []string
Expand Down Expand Up @@ -241,7 +241,7 @@ var defaultConfig = &Config{
AkamaiServiceConsumerDomain: "",
AlibabaCloudConfigFile: "/etc/kubernetes/alibaba-cloud.json",
AnnotationFilter: "",
AnnotationPrefix: annotations.DefaultAnnotationPrefix,
AnnotationPrefixes: []string{annotations.DefaultAnnotationPrefix, annotations.AlphaAnnotationPrefix},
APIServerURL: "",
AWSAPIRetries: 3,
AWSAssumeRole: "",
Expand Down Expand Up @@ -468,8 +468,8 @@ var allowedSources = []string{
// NewConfig returns new Config object
func NewConfig() *Config {
return &Config{
AnnotationPrefix: annotations.DefaultAnnotationPrefix,
AWSSDCreateTag: map[string]string{},
AnnotationPrefixes: []string{annotations.DefaultAnnotationPrefix, annotations.AlphaAnnotationPrefix},
AWSSDCreateTag: map[string]string{},
}
}

Expand Down Expand Up @@ -540,7 +540,7 @@ func bindFlags(b flags.FlagBinder, cfg *Config) {
// Flags related to processing source
b.BoolVar("always-publish-not-ready-addresses", "Always publish also not ready addresses for headless services (optional)", false, &cfg.AlwaysPublishNotReadyAddresses)
b.StringVar("annotation-filter", "Filter resources queried for endpoints by annotation, using label selector semantics", defaultConfig.AnnotationFilter, &cfg.AnnotationFilter)
b.StringVar("annotation-prefix", "Annotation prefix for external-dns annotations (default: external-dns.kubernetes.io/)", defaultConfig.AnnotationPrefix, &cfg.AnnotationPrefix)
b.StringsVar("annotation-prefix", "Annotation prefix for external-dns annotations (default: external-dns.kubernetes.io/, ); specify multiple times to support additional prefixes", defaultConfig.AnnotationPrefixes, &cfg.AnnotationPrefixes)
b.EnumVar("compatibility", "Process annotation semantics from legacy implementations (optional, options: mate, molecule, kops-dns-controller)", defaultConfig.Compatibility, &cfg.Compatibility, "", "mate", "molecule", "kops-dns-controller")
b.StringVar("connector-source-server", "The server to connect for connector source, valid only when using connector source", defaultConfig.ConnectorSourceServer, &cfg.ConnectorSourceServer)
b.StringVar("crd-source-apiversion", "API version of the CRD for crd source, e.g. `externaldns.k8s.io/v1alpha1`, valid only when using crd source", defaultConfig.CRDSourceAPIVersion, &cfg.CRDSourceAPIVersion)
Expand Down
7 changes: 5 additions & 2 deletions pkg/apis/externaldns/types_test.go
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Expand Up @@ -44,7 +44,7 @@ var (
SkipperRouteGroupVersion: "zalando.org/v1",
Sources: []string{"service"},
Namespace: "",
AnnotationPrefix: "external-dns.kubernetes.io/",
AnnotationPrefixes: []string{"external-dns.kubernetes.io/", "external-dns.alpha.kubernetes.io/"},
FQDNTemplate: nil,
Compatibility: "",
Provider: ProviderGoogle,
Expand Down Expand Up @@ -150,7 +150,7 @@ var (
SkipperRouteGroupVersion: "zalando.org/v2",
Sources: []string{"service", "ingress", "connector"},
Namespace: "namespace",
AnnotationPrefix: "external-dns.kubernetes.io/",
AnnotationPrefixes: []string{"external-dns.example.com/", "external-dns.alpha.example.com/"},
IgnoreHostnameAnnotation: true,
IgnoreNonHostNetworkPods: true,
IgnoreIngressTLSSpec: true,
Expand Down Expand Up @@ -312,6 +312,8 @@ func TestParseFlags(t *testing.T) {
"--server=http://127.0.0.1:8080",
"--kubeconfig=/some/path",
"--request-timeout=77s",
"--annotation-prefix=external-dns.example.com/",
"--annotation-prefix=external-dns.alpha.example.com/",
"--gloo-namespace=gloo-not-system",
"--gloo-namespace=gloo-second-system",
"--skipper-routegroup-groupversion=zalando.org/v2",
Expand Down Expand Up @@ -445,6 +447,7 @@ func TestParseFlags(t *testing.T) {
"EXTERNAL_DNS_SERVER": "http://127.0.0.1:8080",
"EXTERNAL_DNS_KUBECONFIG": "/some/path",
"EXTERNAL_DNS_REQUEST_TIMEOUT": "77s",
"EXTERNAL_DNS_ANNOTATION_PREFIX": "external-dns.example.com/\nexternal-dns.alpha.example.com/",
"EXTERNAL_DNS_CONTOUR_LOAD_BALANCER": "heptio-contour-other/contour-other",
"EXTERNAL_DNS_GLOO_NAMESPACE": "gloo-not-system\ngloo-second-system",
"EXTERNAL_DNS_SKIPPER_ROUTEGROUP_GROUPVERSION": "zalando.org/v2",
Expand Down
11 changes: 8 additions & 3 deletions pkg/apis/externaldns/validation/validation.go
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Expand Up @@ -56,11 +56,16 @@ func ValidateConfig(cfg *externaldns.Config) error {
return errors.New("--annotation-filter does not specify a valid label selector")
}

if cfg.AnnotationPrefix == "" {
if len(cfg.AnnotationPrefixes) == 0 {
return errors.New("--annotation-prefix cannot be empty")
}
if !strings.HasSuffix(cfg.AnnotationPrefix, "/") {
return errors.New("--annotation-prefix must end with '/'")
for _, prefix := range cfg.AnnotationPrefixes {
if len(prefix) == 0 {
return errors.New("--annotation-prefix cannot be empty")
}
if !strings.HasSuffix(prefix, "/") {
return errors.New("--annotation-prefix must end with '/'")
}
}

if cfg.KubeAPIQPS <= 0 {
Expand Down
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