Remove string checking in API error handling

Use strongly typed errors to set HTTP status codes.
Error interfaces are defined in the api/errors package and errors
returned from controllers are checked against these interfaces.

Errors can be wraeped in a pkg/errors.Causer, as long as somewhere in the
line of causes one of the interfaces is implemented. The special error
interfaces take precedence over Causer, meaning if both Causer and one
of the new error interfaces are implemented, the Causer is not
traversed.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

1 files changed, 70 insertions, 14 deletions

diff --git a/distribution/errors.go b/distribution/errors.go
index 0e4942d6a6..dd6ff0a9aa 100644
--- a/distribution/errors.go
+++ b/distribution/errors.go
@@ -1,6 +1,7 @@
 package distribution
 
 import (
+	"fmt"
 	"net/url"
 	"strings"
 	"syscall"
@@ -12,7 +13,6 @@ import (
 	"github.com/docker/distribution/registry/client"
 	"github.com/docker/distribution/registry/client/auth"
 	"github.com/docker/docker/distribution/xfer"
-	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -60,6 +60,45 @@ func shouldV2Fallback(err errcode.Error) bool {
 	return false
 }
 
+type notFoundError struct {
+	cause errcode.Error
+	ref   reference.Named
+}
+
+func (e notFoundError) Error() string {
+	switch e.cause.Code {
+	case errcode.ErrorCodeDenied:
+		// ErrorCodeDenied is used when access to the repository was denied
+		return fmt.Sprintf("pull access denied for %s, repository does not exist or may require 'docker login'", reference.FamiliarName(e.ref))
+	case v2.ErrorCodeManifestUnknown:
+		return fmt.Sprintf("manifest for %s not found", reference.FamiliarString(e.ref))
+	case v2.ErrorCodeNameUnknown:
+		return fmt.Sprintf("repository %s not found", reference.FamiliarName(e.ref))
+	}
+	// Shouldn't get here, but this is better than returning an empty string
+	return e.cause.Message
+}
+
+func (e notFoundError) NotFound() {}
+
+func (e notFoundError) Cause() error {
+	return e.cause
+}
+
+type unknownError struct {
+	cause error
+}
+
+func (e unknownError) Error() string {
+	return e.cause.Error()
+}
+
+func (e unknownError) Cause() error {
+	return e.cause
+}
+
+func (e unknownError) Unknown() {}
+
 // 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
@@ -74,25 +113,15 @@ func TranslatePullError(err error, ref reference.Named) error {
 			return TranslatePullError(v[0], ref)
 		}
 	case errcode.Error:
-		var newErr error
 		switch v.Code {
-		case errcode.ErrorCodeDenied:
-			// ErrorCodeDenied is used when access to the repository was denied
-			newErr = errors.Errorf("pull access denied for %s, repository does not exist or may require 'docker login'", reference.FamiliarName(ref))
-		case v2.ErrorCodeManifestUnknown:
-			newErr = errors.Errorf("manifest for %s not found", reference.FamiliarString(ref))
-		case v2.ErrorCodeNameUnknown:
-			newErr = errors.Errorf("repository %s not found", reference.FamiliarName(ref))
-		}
-		if newErr != nil {
-			logrus.Infof("Translating %q to %q", err, newErr)
-			return newErr
+		case errcode.ErrorCodeDenied, v2.ErrorCodeManifestUnknown, v2.ErrorCodeNameUnknown:
+			return notFoundError{v, ref}
 		}
 	case xfer.DoNotRetry:
 		return TranslatePullError(v.Err, ref)
 	}
 
-	return err
+	return unknownError{err}
 }
 
 // continueOnError returns true if we should fallback to the next endpoint
@@ -157,3 +186,30 @@ func retryOnError(err error) error {
 	// add them to the switch above.
 	return err
 }
+
+type invalidManifestClassError struct {
+	mediaType string
+	class     string
+}
+
+func (e invalidManifestClassError) Error() string {
+	return fmt.Sprintf("Encountered remote %q(%s) when fetching", e.mediaType, e.class)
+}
+
+func (e invalidManifestClassError) InvalidParameter() {}
+
+type invalidManifestFormatError struct{}
+
+func (invalidManifestFormatError) Error() string {
+	return "unsupported manifest format"
+}
+
+func (invalidManifestFormatError) InvalidParameter() {}
+
+type reservedNameError string
+
+func (e reservedNameError) Error() string {
+	return "'" + string(e) + "' is a reserved name"
+}
+
+func (e reservedNameError) Forbidden() {}