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fix(provider): normalize alias=A/AAAA to alias=true after AdjustEndpoints (#6454)
* fix(provider): normalize alias=A/AAAA to alias=true after AdjustEndpoints Signed-off-by: u-kai <76635578+u-kai@users.noreply.github.com> * refactor(provider): move AliasNormalizingProvider wrapping into factory.Select Signed-off-by: u-kai <76635578+u-kai@users.noreply.github.com> * refactor(provider): rename AliasNormalizingProvider to AliasNormalizingMiddleware Signed-off-by: u-kai <76635578+u-kai@users.noreply.github.com> * test(factory): restore inner provider type assertions after middleware wrapping Signed-off-by: u-kai <76635578+u-kai@users.noreply.github.com> * refactor(factory): move AliasNormalizingMiddleware into factory package Signed-off-by: u-kai <76635578+u-kai@users.noreply.github.com> --------- Signed-off-by: u-kai <76635578+u-kai@users.noreply.github.com>
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Lines changed: 165 additions & 4 deletions

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‎provider/factory/alias_normalizer.go‎

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/*
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Copyright 2026 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package factory
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import (
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"sigs.k8s.io/external-dns/endpoint"
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"sigs.k8s.io/external-dns/provider"
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)
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// AliasNormalizingMiddleware wraps a Provider and normalizes alias ProviderSpecific
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// values after AdjustEndpoints. Providers may convert CNAME endpoints to A/AAAA
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// alias records but leave the alias property as "A" or "AAAA", while Records()
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// always returns "true" for alias records. This mismatch causes the plan to
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// generate a spurious update on every reconciliation loop.
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type AliasNormalizingMiddleware struct {
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provider.Provider
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}
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func newAliasNormalizingMiddleware(p provider.Provider) *AliasNormalizingMiddleware {
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return &AliasNormalizingMiddleware{Provider: p}
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}
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// AdjustEndpoints delegates to the inner provider then normalizes alias values
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// so they match what Records() returns.
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func (p *AliasNormalizingMiddleware) AdjustEndpoints(endpoints []*endpoint.Endpoint) ([]*endpoint.Endpoint, error) {
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eps, err := p.Provider.AdjustEndpoints(endpoints)
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if err != nil {
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return nil, err
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}
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for _, ep := range eps {
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alias := ep.GetAliasProperty()
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if (ep.RecordType == endpoint.RecordTypeA && alias == endpoint.AliasA) ||
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(ep.RecordType == endpoint.RecordTypeAAAA && alias == endpoint.AliasAAAA) {
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ep.SetProviderSpecificProperty(endpoint.ProviderSpecificAlias, string(endpoint.AliasTrue))
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}
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}
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return eps, nil
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}

‎provider/factory/alias_normalizer_test.go‎

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/*
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Copyright 2026 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package factory
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import (
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"context"
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"testing"
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"github.com/stretchr/testify/assert"
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"github.com/stretchr/testify/require"
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"sigs.k8s.io/external-dns/endpoint"
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"sigs.k8s.io/external-dns/plan"
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"sigs.k8s.io/external-dns/provider"
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)
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type stubProvider struct {
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provider.BaseProvider
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}
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func (s *stubProvider) Records(_ context.Context) ([]*endpoint.Endpoint, error) { return nil, nil }
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func (s *stubProvider) ApplyChanges(_ context.Context, _ *plan.Changes) error { return nil }
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func (s *stubProvider) AdjustEndpoints(eps []*endpoint.Endpoint) ([]*endpoint.Endpoint, error) {
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return eps, nil
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}
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func TestAliasNormalizingMiddleware(t *testing.T) {
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tests := []struct {
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name string
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recordType string
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aliasIn endpoint.AliasType
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aliasWanted endpoint.AliasType
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}{
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{
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name: "A with alias=A normalized to true",
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recordType: endpoint.RecordTypeA,
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aliasIn: endpoint.AliasA,
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aliasWanted: endpoint.AliasTrue,
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},
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{
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name: "AAAA with alias=AAAA normalized to true",
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recordType: endpoint.RecordTypeAAAA,
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aliasIn: endpoint.AliasAAAA,
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aliasWanted: endpoint.AliasTrue,
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},
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{
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name: "A with alias=true unchanged",
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recordType: endpoint.RecordTypeA,
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aliasIn: endpoint.AliasTrue,
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aliasWanted: endpoint.AliasTrue,
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},
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{
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name: "A with alias=AAAA not touched",
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recordType: endpoint.RecordTypeA,
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aliasIn: endpoint.AliasAAAA,
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aliasWanted: endpoint.AliasAAAA,
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},
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{
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name: "AAAA with alias=A not touched",
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recordType: endpoint.RecordTypeAAAA,
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aliasIn: endpoint.AliasA,
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aliasWanted: endpoint.AliasA,
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},
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{
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name: "A with alias=false unchanged",
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recordType: endpoint.RecordTypeA,
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aliasIn: endpoint.AliasFalse,
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aliasWanted: endpoint.AliasFalse,
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},
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{
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name: "A with no alias property unchanged",
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recordType: endpoint.RecordTypeA,
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aliasIn: endpoint.AliasNone,
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aliasWanted: endpoint.AliasNone,
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},
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}
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for _, tt := range tests {
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t.Run(tt.name, func(t *testing.T) {
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ep := endpoint.NewEndpoint("example.com", tt.recordType, "target.example.com")
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if tt.aliasIn != endpoint.AliasNone {
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ep = ep.WithProviderSpecific(endpoint.ProviderSpecificAlias, string(tt.aliasIn))
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}
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p := newAliasNormalizingMiddleware(&stubProvider{})
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result, err := p.AdjustEndpoints([]*endpoint.Endpoint{ep})
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require.NoError(t, err)
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require.Len(t, result, 1)
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assert.Equal(t, tt.aliasWanted, result[0].GetAliasProperty())
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})
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}
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}

‎provider/factory/provider.go‎

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@@ -67,10 +67,10 @@ func Select(
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if err != nil {
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return nil, err
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}
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if p != nil && cfg.ProviderCacheTime > 0 {
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return provider.NewCachedProvider(p, cfg.ProviderCacheTime), nil
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if cfg.ProviderCacheTime > 0 {
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p = provider.NewCachedProvider(p, cfg.ProviderCacheTime)
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}
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return p, nil
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return newAliasNormalizingMiddleware(p), nil
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}
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// providers looks up the constructor for the named provider.

‎provider/factory/provider_test.go‎

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@@ -134,7 +134,9 @@ func TestSelectProvider(t *testing.T) {
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} else {
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require.NoError(t, err)
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require.NotNil(t, p)
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assert.Contains(t, reflect.TypeOf(p).String(), tt.expectedType)
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mw, ok := p.(*AliasNormalizingMiddleware)
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require.True(t, ok, "expected outer *AliasNormalizingMiddleware, got %T", p)
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assert.Equal(t, tt.expectedType, reflect.TypeOf(mw.Provider).String())
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}
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})
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}

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