Merge pull request #5149 from saikatharryc/fix-txt-record-panic

fix(registry): handle empty targets in TXT records logging an error

Author: k8s-ci-robot

registry/txt.go

@@ -146,6 +146,11 @@ func (im *TXTRegistry) Records(ctx context.Context) ([]*endpoint.Endpoint, error
 			continue
 		}
 		// We simply assume that TXT records for the registry will always have only one target.
+		// If there are no targets (e.g for routing policy based records in google), direct targets will be empty
+		if len(record.Targets) == 0 {
+			log.Errorf("TXT record has no targets %s", record.DNSName)
+			continue
+		}
 		labels, err := endpoint.NewLabelsFromString(record.Targets[0], im.txtEncryptAESKey)
 		if errors.Is(err, endpoint.ErrInvalidHeritage) {
 			// if no heritage is found or it is invalid

registry/txt_test.go

@@ -26,6 +26,8 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
+	log "github.com/sirupsen/logrus"
+
 	"sigs.k8s.io/external-dns/endpoint"
 	"sigs.k8s.io/external-dns/internal/testutils"
 	"sigs.k8s.io/external-dns/plan"
@@ -1798,3 +1800,40 @@ func TestApplyChangesWithNewFormatOnly(t *testing.T) {
 			"TXT record should have 'a-' prefix when using new format only")
 	}
 }
+
+func TestTXTRegistryRecordsWithEmptyTargets(t *testing.T) {
+	ctx := context.Background()
+	p := inmemory.NewInMemoryProvider()
+	p.CreateZone(testZone)
+	p.ApplyChanges(ctx, &plan.Changes{
+		Create: []*endpoint.Endpoint{
+			{
+				DNSName:    "empty-targets.test-zone.example.org",
+				RecordType: endpoint.RecordTypeTXT,
+				Targets:    endpoint.Targets{},
+			},
+			{
+				DNSName:    "valid-targets.test-zone.example.org",
+				RecordType: endpoint.RecordTypeTXT,
+				Targets:    endpoint.Targets{"target1"},
+			},
+		},
+	})
+
+	r, _ := NewTXTRegistry(p, "", "", "owner", time.Hour, "", []string{}, []string{}, false, nil, false)
+	b := testutils.LogsToBuffer(log.ErrorLevel, t)
+	records, err := r.Records(ctx)
+	require.NoError(t, err)
+
+	expectedRecords := []*endpoint.Endpoint{
+		{
+			DNSName:    "valid-targets.test-zone.example.org",
+			Targets:    endpoint.Targets{"target1"},
+			RecordType: endpoint.RecordTypeTXT,
+			Labels:     map[string]string{},
+		},
+	}
+
+	assert.True(t, testutils.SameEndpoints(records, expectedRecords))
+	assert.Contains(t, b.String(), "TXT record has no targets empty-targets.test-zone.example.org")
+}