Adding error codes to image package

Signed-off-by: Srini Brahmaroutu <srbrahma@us.ibm.com>

errors/image.go

@@ -0,0 +1,20 @@
+package errors
+
+// This file contains all of the errors that can be generated from the
+// docker/image component.
+
+import (
+	"net/http"
+
+	"github.com/docker/distribution/registry/api/errcode"
+)
+
+var (
+	// ErrorCodeInvalidImageID is generated when image id specified is incorrectly formatted.
+	ErrorCodeInvalidImageID = errcode.Register(errGroup, errcode.ErrorDescriptor{
+		Value:          "INVALIDIMAGEID",
+		Message:        "image ID '%s' is invalid ",
+		Description:    "The specified image id is incorrectly formatted",
+		HTTPStatusCode: http.StatusInternalServerError,
+	})
+)

image/image.go

@@ -2,10 +2,10 @@ package image
 
 import (
 	"encoding/json"
-	"fmt"
 	"regexp"
 	"time"
 
+	derr "github.com/docker/docker/errors"
 	"github.com/docker/docker/runconfig"
 )
 
@@ -53,7 +53,7 @@ func NewImgJSON(src []byte) (*Image, error) {
 // ValidateID checks whether an ID string is a valid image ID.
 func ValidateID(id string) error {
 	if ok := validHex.MatchString(id); !ok {
-		return fmt.Errorf("image ID '%s' is invalid", id)
+		return derr.ErrorCodeInvalidImageID.WithArgs(id)
 	}
 	return nil
 }