UPSTREAM: <carry>: pkg/migrator: Log some errors on V(2)

Some errors that can happen when writing resources back during migration
are not particularly significant, yet they can cause a lot or log spam.

This change marks some errors coming from the try function to be logged
on V(2) so that there are not that many log messages. These include:

* conflict
* not found
* UID precondition failed (effectively a conflict)

Author: tchap

pkg/migrator/core.go

@@ -32,7 +32,6 @@ import (
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/client-go/dynamic"
 	"k8s.io/klog/v2"
-
 	"sigs.k8s.io/kube-storage-version-migrator/pkg/migrator/metrics"
 )
 
@@ -209,19 +208,11 @@ func (m *migrator) migrateOneItem(ctx context.Context, item *unstructured.Unstru
 			return nil
 		}
 		if canRetry(err) {
-			seconds, delay := errors.SuggestsClientDelay(err)
-			switch {
-			case delay && len(namespace) > 0:
-				klog.Warningf("migration of %s, in the %s namespace, will be retried after a %ds delay: %v", name, namespace, seconds, err)
-				time.Sleep(time.Duration(seconds) * time.Second)
-			case delay:
-				klog.Warningf("migration of %s will be retried after a %ds delay: %v", name, seconds, err)
-				time.Sleep(time.Duration(seconds) * time.Second)
-			case !delay && len(namespace) > 0:
-				klog.Warningf("migration of %s, in the %s namespace, will be retried: %v", name, namespace, err)
-			default:
-				klog.Warningf("migration of %s will be retried: %v", name, err)
-			}
+			delaySeconds, _ := errors.SuggestsClientDelay(err)
+			delay := time.Duration(delaySeconds) * time.Second
+			klog.V(logLevelForTryError(err)).InfoS("Retrying migration",
+				"object", klog.KRef(namespace, name), "delay", delay, "err", err)
+			time.Sleep(delay)
 			continue
 		}
 		// error is not retriable
@@ -244,7 +235,7 @@ func (m *migrator) try(ctx context.Context, namespace, name string, item *unstru
 	if err == nil {
 		return false, nil
 	}
-	return errors.IsConflict(err), err
+	return isConflictError(err), err
 
 	// TODO: The oc admin uses a defer function to do bandwidth limiting
 	// after doing all operations. The rate limiter is marked as an alpha

pkg/migrator/errors.go

@@ -21,6 +21,7 @@ import (
 
 	"k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/util/net"
+	"k8s.io/klog/v2"
 )
 
 // ErrRetriable is a wrapper for an error that a migrator may use to indicate the
@@ -52,6 +53,18 @@ func isConnectionRefusedError(err error) bool {
 	return strings.Contains(err.Error(), "connection refused")
 }
 
+// isUIDPreconditionError checks whether the error contains "Precondition failed: UID in precondition".
+// This error message is typically present when the resource is deleted before it can be written back.
+func isUIDPreconditionError(err error) bool {
+	return strings.Contains(err.Error(), "Precondition failed: UID in precondition")
+}
+
+// isConflictError checks whether the given error is a conflict error.
+// This is true when errors.IsConflict or isUIDPreconditionError returns true.
+func isConflictError(err error) bool {
+	return errors.IsConflict(err) || isUIDPreconditionError(err)
+}
+
 // interpret adds retry information to the provided error. And it might change
 // the error to nil.
 func interpret(err error) error {
@@ -63,7 +76,7 @@ func interpret(err error) error {
 		return nil
 	case errors.IsMethodNotSupported(err):
 		return ErrNotRetriable{err}
-	case errors.IsConflict(err):
+	case isConflictError(err):
 		return ErrRetriable{err}
 	case errors.IsServerTimeout(err):
 		return ErrRetriable{err}
@@ -91,3 +104,12 @@ func canRetry(err error) bool {
 	}
 	return true
 }
+
+func logLevelForTryError(err error) klog.Level {
+	switch {
+	case errors.IsNotFound(err), isConflictError(err):
+		return 2
+	default:
+		return 0
+	}
+}