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, 5 insertions, 4 deletions

diff --git a/registry/service.go b/registry/service.go
index b4f747380a..d36b11f0e1 100644
--- a/registry/service.go
+++ b/registry/service.go
@@ -2,7 +2,6 @@ package registry
 
 import (
 	"crypto/tls"
-	"fmt"
 	"net/http"
 	"net/url"
 	"strings"
@@ -14,6 +13,7 @@ import (
 	"github.com/docker/distribution/registry/client/auth"
 	"github.com/docker/docker/api/types"
 	registrytypes "github.com/docker/docker/api/types/registry"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
@@ -117,12 +117,12 @@ func (s *DefaultService) Auth(ctx context.Context, authConfig *types.AuthConfig,
 	}
 	u, err := url.Parse(serverAddress)
 	if err != nil {
-		return "", "", fmt.Errorf("unable to parse server address: %v", err)
+		return "", "", validationError{errors.Errorf("unable to parse server address: %v", err)}
 	}
 
 	endpoints, err := s.LookupPushEndpoints(u.Host)
 	if err != nil {
-		return "", "", err
+		return "", "", validationError{err}
 	}
 
 	for _, endpoint := range endpoints {
@@ -140,6 +140,7 @@ func (s *DefaultService) Auth(ctx context.Context, authConfig *types.AuthConfig,
 			logrus.Infof("Error logging in to %s endpoint, trying next endpoint: %v", endpoint.Version, err)
 			continue
 		}
+
 		return "", "", err
 	}
 
@@ -258,7 +259,7 @@ type APIEndpoint struct {
 }
 
 // ToV1Endpoint returns a V1 API endpoint based on the APIEndpoint
-func (e APIEndpoint) ToV1Endpoint(userAgent string, metaHeaders http.Header) (*V1Endpoint, error) {
+func (e APIEndpoint) ToV1Endpoint(userAgent string, metaHeaders http.Header) *V1Endpoint {
 	return newV1Endpoint(*e.URL, e.TLSConfig, userAgent, metaHeaders)
 }