distribution: un-export internal errors and error-utilities

un-exports errors that were only used internally:

- Remove ErrNoSupport as it was not emitted anywhere
- ImageConfigPullError -> imageConfigPullError
- TranslatePullError() -> translatePullError()

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

distribution/errors.go

@@ -18,17 +18,6 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-// ErrNoSupport is an error type used for errors indicating that an operation
-// is not supported. It encapsulates a more specific error.
-type ErrNoSupport struct{ Err error }
-
-func (e ErrNoSupport) Error() string {
-	if e.Err == nil {
-		return "not supported"
-	}
-	return e.Err.Error()
-}
-
 // fallbackError wraps an error that can possibly allow fallback to a different
 // endpoint.
 type fallbackError struct {
@@ -74,18 +63,18 @@ func (e notFoundError) Cause() error {
 	return e.cause
 }
 
-// TranslatePullError is used to convert an error from a registry pull
+// translatePullError is used to convert an error from a registry pull
 // operation to an error representing the entire pull operation. Any error
 // information which is not used by the returned error gets output to
 // log at info level.
-func TranslatePullError(err error, ref reference.Named) error {
+func translatePullError(err error, ref reference.Named) error {
 	switch v := err.(type) {
 	case errcode.Errors:
 		if len(v) != 0 {
 			for _, extra := range v[1:] {
-				logrus.Infof("Ignoring extra error returned from registry: %v", extra)
+				logrus.WithError(extra).Infof("Ignoring extra error returned from registry")
 			}
-			return TranslatePullError(v[0], ref)
+			return translatePullError(v[0], ref)
 		}
 	case errcode.Error:
 		switch v.Code {
@@ -93,7 +82,7 @@ func TranslatePullError(err error, ref reference.Named) error {
 			return notFoundError{v, ref}
 		}
 	case xfer.DoNotRetry:
-		return TranslatePullError(v.Err, ref)
+		return translatePullError(v.Err, ref)
 	}
 
 	return errdefs.Unknown(err)
@@ -125,14 +114,12 @@ func continueOnError(err error, mirrorEndpoint bool) bool {
 			return true
 		}
 		return continueOnError(v[0], mirrorEndpoint)
-	case ErrNoSupport:
-		return continueOnError(v.Err, mirrorEndpoint)
 	case errcode.Error:
 		return mirrorEndpoint
 	case *client.UnexpectedHTTPResponseError:
 		return true
-	case ImageConfigPullError:
-		// ImageConfigPullError only happens with v2 images, v1 fallback is
+	case imageConfigPullError:
+		// imageConfigPullError only happens with v2 images, v1 fallback is
 		// unnecessary.
 		// Failures from a mirror endpoint should result in fallback to the
 		// canonical repo.

distribution/errors_test.go

@@ -18,15 +18,13 @@ var alwaysContinue = []error{
 	errUnexpected,
 	// nested
 	errcode.Errors{errUnexpected},
-	ErrNoSupport{Err: errUnexpected},
 }
 
 var continueFromMirrorEndpoint = []error{
-	ImageConfigPullError{},
+	imageConfigPullError{},
 	errcode.Error{},
 	// nested
 	errcode.Errors{errcode.Error{}},
-	ErrNoSupport{Err: errcode.Error{}},
 }
 
 var neverContinue = []error{

distribution/pull.go

@@ -64,15 +64,6 @@ func Pull(ctx context.Context, ref reference.Named, imagePullConfig *ImagePullCo
 	var (
 		lastErr error
 
-		// discardNoSupportErrors is used to track whether an endpoint encountered an error of type registry.ErrNoSupport
-		// By default it is false, which means that if an ErrNoSupport error is encountered, it will be saved in lastErr.
-		// As soon as another kind of error is encountered, discardNoSupportErrors is set to true, avoiding the saving of
-		// any subsequent ErrNoSupport errors in lastErr.
-		// It's needed for pull-by-digest on v1 endpoints: if there are only v1 endpoints configured, the error should be
-		// returned and displayed, but if there was a v2 endpoint which supports pull-by-digest, then the last relevant
-		// error is the ones from v2 endpoints not v1.
-		discardNoSupportErrors bool
-
 		// confirmedTLSRegistries is a map indicating which registries
 		// are known to be using TLS. There should never be a plaintext
 		// retry for any of these.
@@ -110,22 +101,12 @@ func Pull(ctx context.Context, ref reference.Named, imagePullConfig *ImagePullCo
 				}
 			}
 			if fallback {
-				if _, ok := err.(ErrNoSupport); !ok {
-					// Because we found an error that's not ErrNoSupport, discard all subsequent ErrNoSupport errors.
-					discardNoSupportErrors = true
-					// append subsequent errors
-					lastErr = err
-				} else if !discardNoSupportErrors {
-					// Save the ErrNoSupport error, because it's either the first error or all encountered errors
-					// were also ErrNoSupport errors.
-					// append subsequent errors
-					lastErr = err
-				}
+				lastErr = err
 				logrus.Infof("Attempting next endpoint for pull after error: %v", err)
 				continue
 			}
 			logrus.Errorf("Not continuing with pull after error: %v", err)
-			return TranslatePullError(err, ref)
+			return translatePullError(err, ref)
 		}
 
 		imagePullConfig.ImageEventLogger(reference.FamiliarString(ref), reference.FamiliarName(repoInfo.Name), "pull")
@@ -136,7 +117,7 @@ func Pull(ctx context.Context, ref reference.Named, imagePullConfig *ImagePullCo
 		lastErr = fmt.Errorf("no endpoints found for %s", reference.FamiliarString(ref))
 	}
 
-	return TranslatePullError(lastErr, ref)
+	return translatePullError(lastErr, ref)
 }
 
 // writeStatus writes a status message to out. If layersDownloaded is true, the

distribution/pull_v2.go

@@ -41,14 +41,14 @@ var (
 	errRootFSInvalid  = errors.New("invalid rootfs in image configuration")
 )
 
-// ImageConfigPullError is an error pulling the image config blob
+// imageConfigPullError is an error pulling the image config blob
 // (only applies to schema2).
-type ImageConfigPullError struct {
+type imageConfigPullError struct {
 	Err error
 }
 
-// Error returns the error string for ImageConfigPullError.
-func (e ImageConfigPullError) Error() string {
+// Error returns the error string for imageConfigPullError.
+func (e imageConfigPullError) Error() string {
 	return "error pulling image configuration: " + e.Err.Error()
 }
 
@@ -619,7 +619,7 @@ func (p *v2Puller) pullSchema2Layers(ctx context.Context, target distribution.De
 	go func() {
 		configJSON, err := p.pullSchema2Config(ctx, target.Digest)
 		if err != nil {
-			configErrChan <- ImageConfigPullError{Err: err}
+			configErrChan <- imageConfigPullError{Err: err}
 			cancel()
 			return
 		}