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Lock down HTTP API error codes

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This commit locks down the set of http error codes that will be part of the
inital V2 specification, proposed in docker/docker#9015. The naming order has
been slightly changed and there are few tweaks to ensure all conditions are
captured but this will be set the docker core will be impleemnted against.

To support this, the errors have been moved into an api/errors package. A new
type, ErrorDescriptor, has been defined to centralize the code, message and
definitions used with each type. The information therein can be used to
generate documentation and response code mappings (yet to come...).

In addition to the refactoring that came along with this change, several tests
have been added to ensure serialization round trips are reliable. This allows
better support for using these error types on the client and server side. This
is coupled with some tweaks in the client code to fix issues with error
reporting.

Other fixes in the client include moving client-specific errors out of the base
package and ensuring that we have correct parameters for finishing uploads.
This commit is contained in:
Stephen J Day 2014-12-09 21:25:54 -08:00
parent 33d89b4bca
commit 7b56d10076
14 changed files with 716 additions and 514 deletions
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135
api/errors/descriptors.go Normal file
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package errors
import "net/http"
// ErrorDescriptor provides relevant information about a given error code.
type ErrorDescriptor struct {
// Code is the error code that this descriptor describes.
Code ErrorCode
// Value provides a unique, string key, often captilized with
// underscores, to identify the error code. This value is used as the
// keyed value when serializing api errors.
Value string
// Message is a short, human readable decription of the error condition
// included in API responses.
Message string
// Description provides a complete account of the errors purpose, suitable
// for use in documentation.
Description string
// DefaultStatusCode should to be returned via the HTTP API. Some error
// may have different status codes depending on the situation.
DefaultStatusCode int
}
var descriptors = []ErrorDescriptor{
{
Code: ErrorCodeUnknown,
Value: "UNKNOWN",
Message: "unknown error",
},
{
Code: ErrorCodeDigestInvalid,
Value: "DIGEST_INVALID",
Message: "provided digest did not match uploaded content",
Description: `When a blob is uploaded, the registry will check that
the content matches the digest provided by the client. The error may
include a detail structure with the key "digest", including the
invalid digest string. This error may also be returned when a manifest
includes an invalid layer digest.`,
DefaultStatusCode: http.StatusBadRequest,
},
{
Code: ErrorCodeSizeInvalid,
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.`,
DefaultStatusCode: http.StatusBadRequest,
},
{
Code: ErrorCodeNameInvalid,
Value: "NAME_INVALID",
Message: "manifest name did not match URI",
Description: `During a manifest upload, if the name in the manifest
does not match the uri name, this error will be returned.`,
DefaultStatusCode: http.StatusBadRequest,
},
{
Code: ErrorCodeTagInvalid,
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.`,
DefaultStatusCode: http.StatusBadRequest,
},
{
Code: ErrorCodeNameUnknown,
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.`,
DefaultStatusCode: http.StatusNotFound,
},
{
Code: ErrorCodeManifestUnknown,
Value: "MANIFEST_UNKNOWN",
Message: "manifest unknown",
Description: `This error is returned when the manifest, identified by
name and tag is unknown to the repository.`,
DefaultStatusCode: http.StatusNotFound,
},
{
Code: ErrorCodeManifestInvalid,
Value: "MANIFEST_INVALID",
Message: "manifest invalid",
Description: `During upload, manifests undergo several checks ensuring
validity. If those checks fail, this error may be returned, unless a
more specific error is included.`,
DefaultStatusCode: http.StatusBadRequest,
},
{
Code: ErrorCodeManifestUnverified,
Value: "MANIFEST_UNVERIFIED",
Message: "manifest failed signature verification",
Description: `During manifest upload, if the manifest fails signature
verification, this error will be returned.`,
DefaultStatusCode: http.StatusBadRequest,
},
{
Code: ErrorCodeBlobUnknown,
Value: "BLOB_UNKNOWN",
Message: "blob unknown to registry",
Description: `This error may be returned when a blob is unknown to the
registry in a specified repository. This can be returned with a
standard get or if a manifest references an unknown layer during
upload.`,
DefaultStatusCode: http.StatusNotFound,
},
{
Code: ErrorCodeBlobUploadUnknown,
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.`,
DefaultStatusCode: http.StatusNotFound,
},
}
var errorCodeToDescriptors map[ErrorCode]ErrorDescriptor
var idToDescriptors map[string]ErrorDescriptor
func init() {
errorCodeToDescriptors = make(map[ErrorCode]ErrorDescriptor, len(descriptors))
idToDescriptors = make(map[string]ErrorDescriptor, len(descriptors))
for _, descriptor := range descriptors {
errorCodeToDescriptors[descriptor.Code] = descriptor
idToDescriptors[descriptor.Value] = descriptor
}
}

193
api/errors/errors.go Normal file
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// Package errors describes the error codes that may be returned via the
// Docker Registry JSON HTTP API V2. In addition to declaractions,
// descriptions about the error codes and the conditions causing them are
// avialable in detail.
//
// Error definitions here are considered to be locked down for the V2 registry
// api. Any changes must be considered carefully and should not proceed
// without a change proposal in docker core.
package errors
import (
"fmt"
"strings"
)
// ErrorCode represents the error type. The errors are serialized via strings
// and the integer format may change and should *never* be exported.
type ErrorCode int
const (
// ErrorCodeUnknown is a catch-all for errors not defined below.
ErrorCodeUnknown ErrorCode = iota
// 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
// 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
)
// 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
}
// Descriptor returns the descriptor for the error code.
func (ec ErrorCode) Descriptor() ErrorDescriptor {
d, ok := errorCodeToDescriptors[ec]
if !ok {
return ErrorCodeUnknown.Descriptor()
}
return d
}
// String returns the canonical identifier for this error code.
func (ec ErrorCode) String() string {
return ec.Descriptor().Value
}
// Message returned the human-readable error message for this error code.
func (ec ErrorCode) Message() string {
return ec.Descriptor().Message
}
// MarshalText encodes the receiver into UTF-8-encoded text and returns the
// result.
func (ec ErrorCode) MarshalText() (text []byte, err error) {
return []byte(ec.String()), nil
}
// UnmarshalText decodes the form generated by MarshalText.
func (ec *ErrorCode) UnmarshalText(text []byte) error {
desc, ok := idToDescriptors[string(text)]
if !ok {
desc = ErrorCodeUnknown.Descriptor()
}
*ec = desc.Code
return nil
}
// Error provides a wrapper around ErrorCode with extra Details provided.
type Error struct {
Code ErrorCode `json:"code"`
Message string `json:"message,omitempty"`
Detail interface{} `json:"detail,omitempty"`
}
// Error returns a human readable representation of the error.
func (e Error) Error() string {
return fmt.Sprintf("%s: %s",
strings.ToLower(strings.Replace(e.Code.String(), "_", " ", -1)),
e.Message)
}
// Errors provides the envelope for multiple errors and a few sugar methods
// for use within the application.
type Errors struct {
Errors []Error `json:"errors,omitempty"`
}
// Push pushes an error on to the error stack, with the optional detail
// argument. It is a programming error (ie panic) to push more than one
// detail at a time.
func (errs *Errors) Push(code ErrorCode, details ...interface{}) {
if len(details) > 1 {
panic("please specify zero or one detail items for this error")
}
var detail interface{}
if len(details) > 0 {
detail = details[0]
}
if err, ok := detail.(error); ok {
detail = err.Error()
}
errs.PushErr(Error{
Code: code,
Message: code.Message(),
Detail: detail,
})
}
// PushErr pushes an error interface onto the error stack.
func (errs *Errors) PushErr(err error) {
switch err.(type) {
case Error:
errs.Errors = append(errs.Errors, err.(Error))
default:
errs.Errors = append(errs.Errors, Error{Message: err.Error()})
}
}
func (errs *Errors) Error() string {
switch errs.Len() {
case 0:
return "<nil>"
case 1:
return errs.Errors[0].Error()
default:
msg := "errors:\n"
for _, err := range errs.Errors {
msg += err.Error() + "\n"
}
return msg
}
}
// Clear clears the errors.
func (errs *Errors) Clear() {
errs.Errors = errs.Errors[:0]
}
// Len returns the current number of errors.
func (errs *Errors) Len() int {
return len(errs.Errors)
}

165
api/errors/errors_test.go Normal file
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package errors
import (
"encoding/json"
"reflect"
"testing"
"github.com/docker/docker-registry/digest"
)
// TestErrorCodes ensures that error code format, mappings and
// marshaling/unmarshaling. round trips are stable.
func TestErrorCodes(t *testing.T) {
for _, desc := range descriptors {
if desc.Code.String() != desc.Value {
t.Fatalf("error code string incorrect: %q != %q", desc.Code.String(), desc.Value)
}
if desc.Code.Message() != desc.Message {
t.Fatalf("incorrect message for error code %v: %q != %q", desc.Code, desc.Code.Message(), desc.Message)
}
// Serialize the error code using the json library to ensure that we
// get a string and it works round trip.
p, err := json.Marshal(desc.Code)
if err != nil {
t.Fatalf("error marshaling error code %v: %v", desc.Code, err)
}
if len(p) <= 0 {
t.Fatalf("expected content in marshaled before for error code %v", desc.Code)
}
// 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)
}
if _, ok := ecUnspecified.(string); !ok {
t.Fatalf("expected a string for error code %v on unmarshal got a %T", desc.Code, 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)
}
if ecUnmarshaled != desc.Code {
t.Fatalf("unexpected error code during error code marshal/unmarshal: %v != %v", ecUnmarshaled, desc.Code)
}
}
}
// TestErrorsManagement does a quick check of the Errors type to ensure that
// members are properly pushed and marshaled.
func TestErrorsManagement(t *testing.T) {
var errs Errors
errs.Push(ErrorCodeDigestInvalid)
errs.Push(ErrorCodeBlobUnknown,
map[string]digest.Digest{"digest": "sometestblobsumdoesntmatter"})
p, err := json.Marshal(errs)
if err != nil {
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\"}}]}"
if string(p) != expectedJSON {
t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
}
errs.Clear()
errs.Push(ErrorCodeUnknown)
expectedJSON = "{\"errors\":[{\"code\":\"UNKNOWN\",\"message\":\"unknown error\"}]}"
p, err = json.Marshal(errs)
if err != nil {
t.Fatalf("error marashaling errors: %v", err)
}
if string(p) != expectedJSON {
t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
}
}
// TestMarshalUnmarshal ensures that api errors can round trip through json
// without losing information.
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) {
t.Fatalf("errors not equal after round trip: %#v != %#v", unmarshaled, errors)
}
}