Merge pull request #711 from stevvooe/errors-marshaling

Initial implementation of API errors data structure

errors.go

@@ -0,0 +1,177 @@
+package registry
+
+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 ErrorCode = iota
+
+	// The following errors can happen during a layer upload.
+	ErrorCodeInvalidChecksum
+	ErrorCodeInvalidLength
+	ErrorCodeInvalidTarsum
+
+	// The following errors can happen during manifest upload.
+	ErrorCodeInvalidName
+	ErrorCodeInvalidTag
+	ErrorCodeUnverifiedManifest
+	ErrorCodeUnknownLayer
+	ErrorCodeUntrustedSignature
+)
+
+var errorCodeStrings = map[ErrorCode]string{
+	ErrorCodeUnknown:            "UNKNOWN",
+	ErrorCodeInvalidChecksum:    "INVALID_CHECKSUM",
+	ErrorCodeInvalidLength:      "INVALID_LENGTH",
+	ErrorCodeInvalidTarsum:      "INVALID_TARSUM",
+	ErrorCodeInvalidName:        "INVALID_NAME",
+	ErrorCodeInvalidTag:         "INVALID_TAG",
+	ErrorCodeUnverifiedManifest: "UNVERIFIED_MANIFEST",
+	ErrorCodeUnknownLayer:       "UNKNOWN_LAYER",
+	ErrorCodeUntrustedSignature: "UNTRUSTED_SIGNATURE",
+}
+
+var errorCodesMessages = map[ErrorCode]string{
+	ErrorCodeUnknown:            "unknown error",
+	ErrorCodeInvalidChecksum:    "provided checksum did not match uploaded content",
+	ErrorCodeInvalidLength:      "provided length did not match content length",
+	ErrorCodeInvalidTarsum:      "provided tarsum did not match binary content",
+	ErrorCodeInvalidName:        "Manifest name did not match URI",
+	ErrorCodeInvalidTag:         "Manifest tag did not match URI",
+	ErrorCodeUnverifiedManifest: "Manifest failed signature validation",
+	ErrorCodeUnknownLayer:       "Referenced layer not available",
+	ErrorCodeUntrustedSignature: "Manifest signed by untrusted source",
+}
+
+var stringToErrorCode map[string]ErrorCode
+
+func init() {
+	stringToErrorCode = make(map[string]ErrorCode, len(errorCodeStrings))
+
+	// Build up reverse error code map
+	for k, v := range errorCodeStrings {
+		stringToErrorCode[v] = k
+	}
+}
+
+// ParseErrorCode attempts to parse the error code string, returning
+// ErrorCodeUnknown if the error is not known.
+func ParseErrorCode(s string) ErrorCode {
+	ec, ok := stringToErrorCode[s]
+
+	if !ok {
+		return ErrorCodeUnknown
+	}
+
+	return ec
+}
+
+// String returns the canonical identifier for this error code.
+func (ec ErrorCode) String() string {
+	s, ok := errorCodeStrings[ec]
+
+	if !ok {
+		return errorCodeStrings[ErrorCodeUnknown]
+	}
+
+	return s
+}
+
+func (ec ErrorCode) Message() string {
+	m, ok := errorCodesMessages[ec]
+
+	if !ok {
+		return errorCodesMessages[ErrorCodeUnknown]
+	}
+
+	return m
+}
+
+func (ec ErrorCode) MarshalText() (text []byte, err error) {
+	return []byte(ec.String()), nil
+}
+
+func (ec *ErrorCode) UnmarshalText(text []byte) error {
+	*ec = stringToErrorCode[string(text)]
+
+	return nil
+}
+
+type Error struct {
+	Code    ErrorCode   `json:"code,omitempty"`
+	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.Title(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]
+	}
+
+	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) {
+	errs.Errors = append(errs.Errors, err)
+}
+
+func (errs *Errors) Error() string {
+	switch len(errs.Errors) {
+	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
+	}
+}
+
+// detailUnknownLayer provides detail for unknown layer errors, returned by
+// image manifest push for layers that are not yet transferred. This intended
+// to only be used on the backend to return detail for this specific error.
+type DetailUnknownLayer struct {
+
+	// Unknown should contain the contents of a layer descriptor, which is a
+	// single json object with the key "blobSum" currently.
+	Unknown struct {
+
+		// BlobSum contains the uniquely identifying tarsum of the layer.
+		BlobSum string `json:"blobSum"`
+	} `json:"unknown"`
+}

errors_test.go

@@ -0,0 +1,77 @@
+package registry
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+// TestErrorCodes ensures that error code format, mappings and
+// marshaling/unmarshaling. round trips are stable.
+func TestErrorCodes(t *testing.T) {
+	for ec, _ := range errorCodeStrings {
+		if ec.String() != errorCodeStrings[ec] {
+			t.Fatalf("error code string incorrect: %q != %q", ec.String(), errorCodeStrings[ec])
+		}
+
+		if ec.Message() != errorCodesMessages[ec] {
+			t.Fatalf("incorrect message for error code %v: %q != !q", ec, ec.Message(), errorCodesMessages[ec])
+		}
+
+		// Serialize the error code using the json library to ensure that we
+		// get a string and it works round trip.
+		p, err := json.Marshal(ec)
+
+		if err != nil {
+			t.Fatalf("error marshaling error code %v: %v", ec, err)
+		}
+
+		if len(p) <= 0 {
+			t.Fatalf("expected content in marshaled before for error code %v: %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", ec, err)
+		}
+
+		if _, ok := ecUnspecified.(string); !ok {
+			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", ec, err)
+		}
+
+		if ecUnmarshaled != ec {
+			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.
+func TestErrorsManagement(t *testing.T) {
+	var errs Errors
+
+	errs.Push(ErrorCodeInvalidChecksum)
+
+	var detail DetailUnknownLayer
+	detail.Unknown.BlobSum = "sometestblobsumdoesntmatter"
+
+	errs.Push(ErrorCodeUnknownLayer, detail)
+
+	p, err := json.Marshal(errs)
+
+	if err != nil {
+		t.Fatalf("error marashaling errors: %v", err)
+	}
+
+	expectedJSON := "{\"errors\":[{\"code\":\"INVALID_CHECKSUM\",\"message\":\"provided checksum did not match uploaded content\"},{\"code\":\"UNKNOWN_LAYER\",\"message\":\"Referenced layer not available\",\"detail\":{\"unknown\":{\"blobSum\":\"sometestblobsumdoesntmatter\"}}}]}"
+
+	if string(p) != expectedJSON {
+		t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
+	}
+}