Round 3 - Add Register function

Signed-off-by: Doug Davis <dug@us.ibm.com>

docs/api/errcode/errors.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/http"
 	"strings"
+	"sync"
 )
 
 // ErrorCode represents the error type. The errors are serialized via strings
@@ -36,49 +37,70 @@ type ErrorDescriptor struct {
 var (
 	errorCodeToDescriptors = map[ErrorCode]ErrorDescriptor{}
 	idToDescriptors        = map[string]ErrorDescriptor{}
+	groupToDescriptors     = map[string][]ErrorDescriptor{}
 )
 
-const (
+// ErrorCodeUnknown is a generic error that can be used as a last
-	// ErrorCodeUnknown is a catch-all for errors not defined below.
+// resort if there is no situation-specific error message that can be used
-	ErrorCodeUnknown ErrorCode = 10000 + iota
+var ErrorCodeUnknown = Register("registry.api.errcode", ErrorDescriptor{
-)
+	Value:   "UNKNOWN",
-
+	Message: "unknown error",
-var errorDescriptors = []ErrorDescriptor{
+	Description: `Generic error returned when the error does not have an
-	{
-		Code:    ErrorCodeUnknown,
-		Value:   "UNKNOWN",
-		Message: "unknown error",
-		Description: `Generic error returned when the error does not have an
 									        API classification.`,
-		HTTPStatusCode: http.StatusInternalServerError,
+	HTTPStatusCode: http.StatusInternalServerError,
-	},
+})
-}
 
-// LoadErrors will register a new set of Errors into the system
+var nextCode = 1000
-func LoadErrors(errs []ErrorDescriptor) {
+var registerLock sync.Mutex
-	for _, descriptor := range errs {
-		if _, ok := idToDescriptors[descriptor.Value]; ok {
-			panic(fmt.Sprintf("ErrorValue %s is already registered", descriptor.Value))
-		}
-		if _, ok := errorCodeToDescriptors[descriptor.Code]; ok {
-			panic(fmt.Sprintf("ErrorCode %d is already registered", descriptor.Code))
-		}
 
-		errorCodeToDescriptors[descriptor.Code] = descriptor
+// Register will make the passed-in error known to the environment and
-		idToDescriptors[descriptor.Value] = descriptor
+// return a new ErrorCode
+func Register(group string, descriptor ErrorDescriptor) ErrorCode {
+	registerLock.Lock()
+	defer registerLock.Unlock()
+	code := ErrorCode(nextCode)
+
+	descriptor.Code = code
+
+	if _, ok := idToDescriptors[descriptor.Value]; ok {
+		panic(fmt.Sprintf("ErrorValue %s is already registered", descriptor.Value))
 	}
-}
+	if _, ok := errorCodeToDescriptors[descriptor.Code]; ok {
-
+		panic(fmt.Sprintf("ErrorCode %d is already registered", descriptor.Code))
-// ParseErrorCode attempts to parse the error code string, returning
-// ErrorCodeUnknown if the error is not known.
-func ParseErrorCode(s string) ErrorCode {
-	desc, ok := idToDescriptors[s]
-
-	if !ok {
-		return ErrorCodeUnknown
 	}
 
-	return desc.Code
+	groupToDescriptors[group] = append(groupToDescriptors[group], descriptor)
+	errorCodeToDescriptors[code] = descriptor
+	idToDescriptors[descriptor.Value] = descriptor
+
+	nextCode++
+	return code
+}
+
+// ParseErrorCode returns the value by the string error code.
+// `ErrorCodeUnknown` will be returned if the error is not known.
+func ParseErrorCode(value string) ErrorCode {
+	ed, ok := idToDescriptors[value]
+	if ok {
+		return ed.Code
+	}
+
+	return ErrorCodeUnknown
+}
+
+// GetGroupNames returns the list of Error group names that are registered
+func GetGroupNames() []string {
+	keys := []string{}
+
+	for k := range groupToDescriptors {
+		keys = append(keys, k)
+	}
+	return keys
+}
+
+// GetErrorCodeGroup returns the named group of error descriptors
+func GetErrorCodeGroup(name string) []ErrorDescriptor {
+	return groupToDescriptors[name]
 }
 
 // Descriptor returns the descriptor for the error code.
@@ -183,8 +205,3 @@ func (errs Errors) Error() string {
 func (errs Errors) Len() int {
 	return len(errs)
 }
-
-// init loads the default errors that are part of the errcode package
-func init() {
-	LoadErrors(errorDescriptors)
-}

docs/api/errcode/errors_test.go

@@ -2,67 +2,86 @@ package errcode
 
 import (
 	"encoding/json"
-	// "reflect"
+	"net/http"
+	"reflect"
 	"testing"
-
-	// "github.com/docker/distribution/digest"
 )
 
 // TestErrorCodes ensures that error code format, mappings and
 // marshaling/unmarshaling. round trips are stable.
 func TestErrorCodes(t *testing.T) {
-	for _, desc := range errorDescriptors {
+	if len(errorCodeToDescriptors) == 0 {
-		if desc.Code.String() != desc.Value {
+		t.Fatal("errors aren't loaded!")
-			t.Fatalf("error code string incorrect: %q != %q", desc.Code.String(), desc.Value)
+	}
+
+	for ec, desc := range errorCodeToDescriptors {
+		if ec != desc.Code {
+			t.Fatalf("error code in descriptor isn't correct, %q != %q", ec, desc.Code)
 		}
 
-		if desc.Code.Message() != desc.Message {
+		if idToDescriptors[desc.Value].Code != ec {
-			t.Fatalf("incorrect message for error code %v: %q != %q", desc.Code, desc.Code.Message(), desc.Message)
+			t.Fatalf("error code in idToDesc isn't correct, %q != %q", idToDescriptors[desc.Value].Code, ec)
 		}
 
-		// Serialize the error code using the json library to ensure that we
+		if ec.Message() != desc.Message {
-		// get a string and it works round trip.
+			t.Fatalf("ec.Message doesn't mtach desc.Message: %q != %q", ec.Message(), desc.Message)
-		p, err := json.Marshal(desc.Code)
+		}
 
+		// Test (de)serializing the ErrorCode
+		p, err := json.Marshal(ec)
 		if err != nil {
-			t.Fatalf("error marshaling error code %v: %v", desc.Code, err)
+			t.Fatalf("couldn't marshal ec %v: %v", ec, err)
 		}
 
 		if len(p) <= 0 {
-			t.Fatalf("expected content in marshaled before for error code %v", desc.Code)
+			t.Fatalf("expected content in marshaled before for error code %v", ec)
 		}
 
 		// First, unmarshal to interface and ensure we have a string.
 		var ecUnspecified interface{}
 		if err := json.Unmarshal(p, &ecUnspecified); err != nil {
-			t.Fatalf("error unmarshaling error code %v: %v", desc.Code, err)
+			t.Fatalf("error unmarshaling error code %v: %v", ec, err)
 		}
 
 		if _, ok := ecUnspecified.(string); !ok {
-			t.Fatalf("expected a string for error code %v on unmarshal got a %T", desc.Code, ecUnspecified)
+			t.Fatalf("expected a string for error code %v on unmarshal got a %T", ec, ecUnspecified)
 		}
 
 		// Now, unmarshal with the error code type and ensure they are equal
 		var ecUnmarshaled ErrorCode
 		if err := json.Unmarshal(p, &ecUnmarshaled); err != nil {
-			t.Fatalf("error unmarshaling error code %v: %v", desc.Code, err)
+			t.Fatalf("error unmarshaling error code %v: %v", ec, err)
 		}
 
-		if ecUnmarshaled != desc.Code {
+		if ecUnmarshaled != ec {
-			t.Fatalf("unexpected error code during error code marshal/unmarshal: %v != %v", ecUnmarshaled, desc.Code)
+			t.Fatalf("unexpected error code during error code marshal/unmarshal: %v != %v", ecUnmarshaled, ec)
 		}
 	}
+
 }
 
 // TestErrorsManagement does a quick check of the Errors type to ensure that
 // members are properly pushed and marshaled.
-/*
+var ErrorCodeTest1 = Register("v2.errors", ErrorDescriptor{
+	Value:          "TEST1",
+	Message:        "test error 1",
+	Description:    `Just a test message #1.`,
+	HTTPStatusCode: http.StatusInternalServerError,
+})
+
+var ErrorCodeTest2 = Register("v2.errors", ErrorDescriptor{
+	Value:          "TEST2",
+	Message:        "test error 2",
+	Description:    `Just a test message #2.`,
+	HTTPStatusCode: http.StatusNotFound,
+})
+
 func TestErrorsManagement(t *testing.T) {
 	var errs Errors
 
-	errs.Push(ErrorCodeDigestInvalid)
+	errs = append(errs, NewError(ErrorCodeTest1))
-	errs.Push(ErrorCodeBlobUnknown,
+	errs = append(errs, NewError(ErrorCodeTest2,
-		map[string]digest.Digest{"digest": "sometestblobsumdoesntmatter"})
+		map[string]interface{}{"digest": "sometestblobsumdoesntmatter"}))
 
 	p, err := json.Marshal(errs)
 
@@ -70,15 +89,25 @@ func TestErrorsManagement(t *testing.T) {
 		t.Fatalf("error marashaling errors: %v", err)
 	}
 
-	expectedJSON := "{\"errors\":[{\"code\":\"DIGEST_INVALID\",\"message\":\"provided digest did not match uploaded content\"},{\"code\":\"BLOB_UNKNOWN\",\"message\":\"blob unknown to registry\",\"detail\":{\"digest\":\"sometestblobsumdoesntmatter\"}}]}"
+	expectedJSON := "[{\"code\":\"TEST1\"},{\"code\":\"TEST2\",\"detail\":{\"digest\":\"sometestblobsumdoesntmatter\"}}]"
 
 	if string(p) != expectedJSON {
 		t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
 	}
 
-	errs.Clear()
+	// Now test the reverse
-	errs.Push(ErrorCodeUnknown)
+	var unmarshaled Errors
-	expectedJSON = "{\"errors\":[{\"code\":\"UNKNOWN\",\"message\":\"unknown error\"}]}"
+	if err := json.Unmarshal(p, &unmarshaled); err != nil {
+		t.Fatalf("unexpected error unmarshaling error envelope: %v", err)
+	}
+
+	if !reflect.DeepEqual(unmarshaled, errs) {
+		t.Fatalf("errors not equal after round trip:\nunmarshaled:\n%#v\n\nerrs:\n%#v", unmarshaled, errs)
+	}
+
+	// Test again with a single value this time
+	errs = Errors{NewError(ErrorCodeUnknown)}
+	expectedJSON = "[{\"code\":\"UNKNOWN\"}]"
 	p, err = json.Marshal(errs)
 
 	if err != nil {
@@ -88,80 +117,15 @@ func TestErrorsManagement(t *testing.T) {
 	if string(p) != expectedJSON {
 		t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
 	}
-}
 
-// TestMarshalUnmarshal ensures that api errors can round trip through json
+	// Now test the reverse
-// without losing information.
+	unmarshaled = nil
-func TestMarshalUnmarshal(t *testing.T) {
-
-	var errors Errors
-
-	for _, testcase := range []struct {
-		description string
-		err         Error
-	}{
-		{
-			description: "unknown error",
-			err: Error{
-
-				Code:    ErrorCodeUnknown,
-				Message: ErrorCodeUnknown.Descriptor().Message,
-			},
-		},
-		{
-			description: "unknown manifest",
-			err: Error{
-				Code:    ErrorCodeManifestUnknown,
-				Message: ErrorCodeManifestUnknown.Descriptor().Message,
-			},
-		},
-		{
-			description: "unknown manifest",
-			err: Error{
-				Code:    ErrorCodeBlobUnknown,
-				Message: ErrorCodeBlobUnknown.Descriptor().Message,
-				Detail:  map[string]interface{}{"digest": "asdfqwerqwerqwerqwer"},
-			},
-		},
-	} {
-		fatalf := func(format string, args ...interface{}) {
-			t.Fatalf(testcase.description+": "+format, args...)
-		}
-
-		unexpectedErr := func(err error) {
-			fatalf("unexpected error: %v", err)
-		}
-
-		p, err := json.Marshal(testcase.err)
-		if err != nil {
-			unexpectedErr(err)
-		}
-
-		var unmarshaled Error
-		if err := json.Unmarshal(p, &unmarshaled); err != nil {
-			unexpectedErr(err)
-		}
-
-		if !reflect.DeepEqual(unmarshaled, testcase.err) {
-			fatalf("errors not equal after round trip: %#v != %#v", unmarshaled, testcase.err)
-		}
-
-		// Roll everything up into an error response envelope.
-		errors.PushErr(testcase.err)
-	}
-
-	p, err := json.Marshal(errors)
-	if err != nil {
-		t.Fatalf("unexpected error marshaling error envelope: %v", err)
-	}
-
-	var unmarshaled Errors
 	if err := json.Unmarshal(p, &unmarshaled); err != nil {
 		t.Fatalf("unexpected error unmarshaling error envelope: %v", err)
 	}
 
-	if !reflect.DeepEqual(unmarshaled, errors) {
+	if !reflect.DeepEqual(unmarshaled, errs) {
-		t.Fatalf("errors not equal after round trip: %#v != %#v", unmarshaled, errors)
+		t.Fatalf("errors not equal after round trip:\nunmarshaled:\n%#v\n\nerrs:\n%#v", unmarshaled, errs)
 	}
+
 }
-*/

docs/api/v2/descriptors.go

@@ -172,13 +172,8 @@ const (
 var APIDescriptor = struct {
 	// RouteDescriptors provides a list of the routes available in the API.
 	RouteDescriptors []RouteDescriptor
-
-	// ErrorDescriptors provides a list of the error codes and their
-	// associated documentation and metadata.
-	ErrorDescriptors []errcode.ErrorDescriptor
 }{
 	RouteDescriptors: routeDescriptors,
-	ErrorDescriptors: errorDescriptors,
 }
 
 // RouteDescriptor describes a route specified by name.

docs/api/v2/errors.go

@@ -6,81 +6,28 @@ import (
 	"github.com/docker/distribution/registry/api/errcode"
 )
 
-const (
+var (
 	// ErrorCodeUnsupported is returned when an operation is not supported.
-	ErrorCodeUnsupported = iota
+	ErrorCodeUnsupported = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
-
-	// ErrorCodeUnauthorized is returned if a request is not authorized.
-	ErrorCodeUnauthorized
-
-	// ErrorCodeDigestInvalid is returned when uploading a blob if the
-	// provided digest does not match the blob contents.
-	ErrorCodeDigestInvalid
-
-	// ErrorCodeSizeInvalid is returned when uploading a blob if the provided
-	// size does not match the content length.
-	ErrorCodeSizeInvalid
-
-	// ErrorCodeNameInvalid is returned when the name in the manifest does not
-	// match the provided name.
-	ErrorCodeNameInvalid
-
-	// ErrorCodeTagInvalid is returned when the tag in the manifest does not
-	// match the provided tag.
-	ErrorCodeTagInvalid
-
-	// ErrorCodeNameUnknown when the repository name is not known.
-	ErrorCodeNameUnknown
-
-	// ErrorCodeManifestUnknown returned when image manifest is unknown.
-	ErrorCodeManifestUnknown
-
-	// ErrorCodeManifestInvalid returned when an image manifest is invalid,
-	// typically during a PUT operation. This error encompasses all errors
-	// encountered during manifest validation that aren't signature errors.
-	ErrorCodeManifestInvalid
-
-	// ErrorCodeManifestUnverified is returned when the manifest fails
-	// signature verfication.
-	ErrorCodeManifestUnverified
-
-	// ErrorCodeManifestBlobUnknown is returned when a manifest blob is
-	// unknown to the registry.
-	ErrorCodeManifestBlobUnknown
-
-	// ErrorCodeBlobUnknown is returned when a blob is unknown to the
-	// registry. This can happen when the manifest references a nonexistent
-	// layer or the result is not found by a blob fetch.
-	ErrorCodeBlobUnknown
-
-	// ErrorCodeBlobUploadUnknown is returned when an upload is unknown.
-	ErrorCodeBlobUploadUnknown
-
-	// ErrorCodeBlobUploadInvalid is returned when an upload is invalid.
-	ErrorCodeBlobUploadInvalid
-)
-
-// ErrorDescriptors provides a list of HTTP API Error codes that may be
-// encountered when interacting with the registry API.
-var errorDescriptors = []errcode.ErrorDescriptor{
-	{
-		Code:    ErrorCodeUnsupported,
 		Value:   "UNSUPPORTED",
 		Message: "The operation is unsupported.",
 		Description: `The operation was unsupported due to a missing
 		implementation or invalid set of parameters.`,
-	},
+	})
-	{
+
-		Code:    ErrorCodeUnauthorized,
+	// ErrorCodeUnauthorized is returned if a request is not authorized.
+	ErrorCodeUnauthorized = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "UNAUTHORIZED",
 		Message: "access to the requested resource is not authorized",
 		Description: `The access controller denied access for the operation on
 		a resource. Often this will be accompanied by a 401 Unauthorized
 		response status.`,
 		HTTPStatusCode: http.StatusForbidden,
-	},
+	})
-	{
+
-		Code:    ErrorCodeDigestInvalid,
+	// ErrorCodeDigestInvalid is returned when uploading a blob if the
+	// provided digest does not match the blob contents.
+	ErrorCodeDigestInvalid = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "DIGEST_INVALID",
 		Message: "provided digest did not match uploaded content",
 		Description: `When a blob is uploaded, the registry will check that
@@ -89,50 +36,60 @@ var errorDescriptors = []errcode.ErrorDescriptor{
 		invalid digest string. This error may also be returned when a manifest
 		includes an invalid layer digest.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeSizeInvalid,
+	// ErrorCodeSizeInvalid is returned when uploading a blob if the provided
+	ErrorCodeSizeInvalid = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "SIZE_INVALID",
 		Message: "provided length did not match content length",
 		Description: `When a layer is uploaded, the provided size will be
 		checked against the uploaded content. If they do not match, this error
 		will be returned.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeNameInvalid,
+	// ErrorCodeNameInvalid is returned when the name in the manifest does not
+	// match the provided name.
+	ErrorCodeNameInvalid = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "NAME_INVALID",
 		Message: "invalid repository name",
 		Description: `Invalid repository name encountered either during
 		manifest validation or any API operation.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeTagInvalid,
+	// ErrorCodeTagInvalid is returned when the tag in the manifest does not
+	// match the provided tag.
+	ErrorCodeTagInvalid = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "TAG_INVALID",
 		Message: "manifest tag did not match URI",
 		Description: `During a manifest upload, if the tag in the manifest
 		does not match the uri tag, this error will be returned.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeNameUnknown,
+	// ErrorCodeNameUnknown when the repository name is not known.
+	ErrorCodeNameUnknown = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "NAME_UNKNOWN",
 		Message: "repository name not known to registry",
 		Description: `This is returned if the name used during an operation is
 		unknown to the registry.`,
 		HTTPStatusCode: http.StatusNotFound,
-	},
+	})
-	{
+
-		Code:    ErrorCodeManifestUnknown,
+	// ErrorCodeManifestUnknown returned when image manifest is unknown.
+	ErrorCodeManifestUnknown = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "MANIFEST_UNKNOWN",
 		Message: "manifest unknown",
 		Description: `This error is returned when the manifest, identified by
 		name and tag is unknown to the repository.`,
 		HTTPStatusCode: http.StatusNotFound,
-	},
+	})
-	{
+
-		Code:    ErrorCodeManifestInvalid,
+	// ErrorCodeManifestInvalid returned when an image manifest is invalid,
+	// typically during a PUT operation. This error encompasses all errors
+	// encountered during manifest validation that aren't signature errors.
+	ErrorCodeManifestInvalid = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "MANIFEST_INVALID",
 		Message: "manifest invalid",
 		Description: `During upload, manifests undergo several checks ensuring
@@ -140,25 +97,32 @@ var errorDescriptors = []errcode.ErrorDescriptor{
 		more specific error is included. The detail will contain information
 		the failed validation.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeManifestUnverified,
+	// ErrorCodeManifestUnverified is returned when the manifest fails
+	// signature verfication.
+	ErrorCodeManifestUnverified = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "MANIFEST_UNVERIFIED",
 		Message: "manifest failed signature verification",
 		Description: `During manifest upload, if the manifest fails signature
 		verification, this error will be returned.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeManifestBlobUnknown,
+	// ErrorCodeManifestBlobUnknown is returned when a manifest blob is
+	// unknown to the registry.
+	ErrorCodeManifestBlobUnknown = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "MANIFEST_BLOB_UNKNOWN",
 		Message: "blob unknown to registry",
 		Description: `This error may be returned when a manifest blob is 
 		unknown to the registry.`,
 		HTTPStatusCode: http.StatusBadRequest,
-	},
+	})
-	{
+
-		Code:    ErrorCodeBlobUnknown,
+	// ErrorCodeBlobUnknown is returned when a blob is unknown to the
+	// registry. This can happen when the manifest references a nonexistent
+	// layer or the result is not found by a blob fetch.
+	ErrorCodeBlobUnknown = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "BLOB_UNKNOWN",
 		Message: "blob unknown to registry",
 		Description: `This error may be returned when a blob is unknown to the
@@ -166,27 +130,23 @@ var errorDescriptors = []errcode.ErrorDescriptor{
 		standard get or if a manifest references an unknown layer during
 		upload.`,
 		HTTPStatusCode: http.StatusNotFound,
-	},
+	})
 
-	{
+	// ErrorCodeBlobUploadUnknown is returned when an upload is unknown.
-		Code:    ErrorCodeBlobUploadUnknown,
+	ErrorCodeBlobUploadUnknown = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "BLOB_UPLOAD_UNKNOWN",
 		Message: "blob upload unknown to registry",
 		Description: `If a blob upload has been cancelled or was never
 		started, this error code may be returned.`,
 		HTTPStatusCode: http.StatusNotFound,
-	},
+	})
-	{
+
-		Code:    ErrorCodeBlobUploadInvalid,
+	// ErrorCodeBlobUploadInvalid is returned when an upload is invalid.
+	ErrorCodeBlobUploadInvalid = errcode.Register("registry.api.v2", errcode.ErrorDescriptor{
 		Value:   "BLOB_UPLOAD_INVALID",
 		Message: "blob upload invalid",
 		Description: `The blob upload encountered an error and can no
 		longer proceed.`,
 		HTTPStatusCode: http.StatusNotFound,
-	},
+	})
-}
+)
-
-// init registers our errors with the errcode system
-func init() {
-	errcode.LoadErrors(errorDescriptors)
-}

docs/handlers/app.go

@@ -452,6 +452,7 @@ func (app *App) authorized(w http.ResponseWriter, r *http.Request, context *Cont
 	if err != nil {
 		switch err := err.(type) {
 		case auth.Challenge:
+			// NOTE(duglin):
 			// Since err.ServeHTTP will set the HTTP status code for us
 			// we need to set the content-type here.  The serveJSON
 			// func will try to do it but it'll be too late at that point.

docs/handlers/app_test.go

@@ -186,11 +186,9 @@ func TestNewApp(t *testing.T) {
 		t.Fatalf("unexpected status code during request: %v", err)
 	}
 
-	/*
+	if req.Header.Get("Content-Type") != "application/json; charset=utf-8" {
-		if req.Header.Get("Content-Type") != "application/json; charset=utf-8" {
+		t.Fatalf("unexpected content-type: %v != %v", req.Header.Get("Content-Type"), "application/json; charset=utf-8")
-			t.Fatalf("unexpected content-type: %v != %v", req.Header.Get("Content-Type"), "application/json; charset=utf-8")
+	}
-		}
-	*/
 
 	expectedAuthHeader := "Bearer realm=\"realm-test\",service=\"service-test\""
 	if e, a := expectedAuthHeader, req.Header.Get("WWW-Authenticate"); e != a {

docs/handlers/helpers.go

@@ -2,9 +2,10 @@ package handlers
 
 import (
 	"encoding/json"
-	"github.com/docker/distribution/registry/api/errcode"
 	"io"
 	"net/http"
+
+	"github.com/docker/distribution/registry/api/errcode"
 )
 
 // serveJSON marshals v and sets the content-type header to