Skip apply empty changes in the cache provider

Change-Id: Icaf1ffe34e75c320d4efbb428f831deb8784cd11

main.go

@@ -421,7 +421,7 @@ func main() {
 	case "txt":
 		r, err = registry.NewTXTRegistry(p, cfg.TXTPrefix, cfg.TXTSuffix, cfg.TXTOwnerID, cfg.TXTCacheInterval, cfg.TXTWildcardReplacement, cfg.ManagedDNSRecordTypes, cfg.ExcludeDNSRecordTypes, cfg.TXTEncryptEnabled, []byte(cfg.TXTEncryptAESKey))
 	case "aws-sd":
-		r, err = registry.NewAWSSDRegistry(p.(*awssd.AWSSDProvider), cfg.TXTOwnerID)
+		r, err = registry.NewAWSSDRegistry(p, cfg.TXTOwnerID)
 	default:
 		log.Fatalf("unknown registry: %s", cfg.Registry)
 	}

provider/cached_provider.go

@@ -5,6 +5,7 @@ import (
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
+	log "github.com/sirupsen/logrus"
 	"sigs.k8s.io/external-dns/endpoint"
 	"sigs.k8s.io/external-dns/plan"
 )
@@ -41,15 +42,23 @@ type CachedProvider struct {
 
 func (c *CachedProvider) Records(ctx context.Context) ([]*endpoint.Endpoint, error) {
 	if c.needRefresh() {
+		log.Info("Records cache provider: refreshing records list cache")
 		c.cache, c.err = c.Provider.Records(ctx)
+		if c.err != nil {
+			log.Errorf("Records cache provider: list records failed: %v", c.err)
+		}
 		c.lastRead = time.Now()
 		cachedRecordsCallsTotal.WithLabelValues("false").Inc()
 	} else {
+		log.Info("Records cache provider: using records list from cache")
 		cachedRecordsCallsTotal.WithLabelValues("true").Inc()
 	}
 	return c.cache, c.err
 }
 func (c *CachedProvider) ApplyChanges(ctx context.Context, changes *plan.Changes) error {
+	if !changes.HasChanges() {
+		return nil
+	}
 	c.Reset()
 	cachedApplyChangesCallsTotal.Inc()
 	return c.Provider.ApplyChanges(ctx, changes)
@@ -63,8 +72,10 @@ func (c *CachedProvider) Reset() {
 
 func (c *CachedProvider) needRefresh() bool {
 	if c.cache == nil || c.err != nil {
+		log.Debug("Records cache provider is not initialized")
 		return true
 	}
+	log.Debug("Records cache last Read: ", c.lastRead, "expiration: ", c.RefreshDelay, " provider expiration:", c.lastRead.Add(c.RefreshDelay), "expired: ", time.Now().After(c.lastRead.Add(c.RefreshDelay)))
 	return time.Now().After(c.lastRead.Add(c.RefreshDelay))
 }
 

provider/cached_provider_test.go

@@ -140,13 +140,39 @@ func TestCachedProviderForcesCacheRefreshOnUpdate(t *testing.T) {
 	_, err := provider.Records(context.Background())
 	require.NoError(t, err)
 
-	t.Run("When the caching time frame is exceeded", func(t *testing.T) {
+	t.Run("When empty changes are applied", func(t *testing.T) {
 		testProvider.records = recordsNotCalled(t)
 		testProvider.applyChanges = func(ctx context.Context, changes *plan.Changes) error {
 			return nil
 		}
 		err := provider.ApplyChanges(context.Background(), &plan.Changes{})
 		assert.NoError(t, err)
+		t.Run("Next call to Records is cached", func(t *testing.T) {
+			testProvider.applyChanges = applyChangesNotCalled(t)
+			testProvider.records = func(ctx context.Context) ([]*endpoint.Endpoint, error) {
+				return []*endpoint.Endpoint{{DNSName: "new.domain.fqdn"}}, nil
+			}
+			endpoints, err := provider.Records(context.Background())
+
+			assert.NoError(t, err)
+			require.NotNil(t, endpoints)
+			require.Len(t, endpoints, 1)
+			require.NotNil(t, endpoints[0])
+			assert.Equal(t, "domain.fqdn", endpoints[0].DNSName)
+		})
+	})
+
+	t.Run("When changes are applied", func(t *testing.T) {
+		testProvider.records = recordsNotCalled(t)
+		testProvider.applyChanges = func(ctx context.Context, changes *plan.Changes) error {
+			return nil
+		}
+		err := provider.ApplyChanges(context.Background(), &plan.Changes{
+			Create: []*endpoint.Endpoint{
+				{DNSName: "hello.world"},
+			},
+		})
+		assert.NoError(t, err)
 		t.Run("Next call to Records is not cached", func(t *testing.T) {
 			testProvider.applyChanges = applyChangesNotCalled(t)
 			testProvider.records = func(ctx context.Context) ([]*endpoint.Endpoint, error) {