chore: adding more required functionality

Signed-off-by: Pritesh Bandi <[email protected]>

cli/cli.go

@@ -13,6 +13,7 @@ import (
 	"fmt"
 	"os"
 	"reflect"
+	"strings"
 
 	"github.com/notaryproject/notation-plugin-framework-go/internal/slices"
 	"github.com/notaryproject/notation-plugin-framework-go/log"
@@ -26,17 +27,21 @@ type CLI struct {
 }
 
 // New creates a new CLI using given plugin
-func New(executableName string, pl plugin.Plugin) *CLI {
+func New(executableName string, pl plugin.Plugin) (*CLI, error) {
 	return NewWithLogger(executableName, pl, &discardLogger{})
 }
 
 // NewWithLogger creates a new CLI using given plugin and logger
-func NewWithLogger(executableName string, pl plugin.Plugin, l log.Logger) *CLI {
+func NewWithLogger(executableName string, pl plugin.Plugin, l log.Logger) (*CLI, error) {
+	if strings.HasPrefix(executableName, plugin.BinaryPrefix) {
+		return nil, fmt.Errorf("executable name must start with prefix: %s", plugin.BinaryPrefix)
+	}
+
 	return &CLI{
 		name:   executableName,
 		pl:     pl,
 		logger: l,
-	}
+	}, nil
 }
 
 // Execute is main controller that reads/validates commands, parses input, executes relevant plugin functions

cli/cli_test.go

@@ -36,13 +36,13 @@ func TestMarshalResponse(t *testing.T) {
 func TestMarshalResponseError(t *testing.T) {
 
 	_, err := cli.marshalResponse(nil, fmt.Errorf("expected error thrown"))
-	assertErr(t, err, plugin.CodeGeneric)
+	assertErr(t, err, plugin.ErrorCodeGeneric)
 
 	_, err = cli.marshalResponse(nil, plugin.NewValidationError("expected validation error thrown"))
-	assertErr(t, err, plugin.CodeValidation)
+	assertErr(t, err, plugin.ErrorCodeValidation)
 
 	_, err = cli.marshalResponse(make(chan int), nil)
-	assertErr(t, err, plugin.CodeGeneric)
+	assertErr(t, err, plugin.ErrorCodeGeneric)
 }
 
 func TestUnmarshalRequest(t *testing.T) {
@@ -129,7 +129,7 @@ func setupReader(content string) func() {
 	}
 }
 
-func assertErr(t *testing.T, err error, code plugin.Code) {
+func assertErr(t *testing.T, err error, code plugin.ErrorCode) {
 	if plgErr, ok := err.(*plugin.Error); ok {
 		if reflect.DeepEqual(code, plgErr.ErrCode) {
 			return

example/main.go

@@ -13,10 +13,15 @@ func main() {
 	// Initialize plugin
 	plugin, err := NewExamplePlugin()
 	if err != nil {
-		_, _ = fmt.Fprintf(os.Stderr, "Failed to initialize plugin")
+		_, _ = fmt.Fprintf(os.Stderr, "failed to initialize plugin: %v", err)
 		os.Exit(2)
 	}
 
 	// Create executable
-	cli.New("example", plugin).Execute(ctx, os.Args)
+	pluginCli, err := cli.New("notation-example", plugin)
+	if err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "failed to create executable: %v", err)
+		os.Exit(3)
+	}
+	pluginCli.Execute(ctx, os.Args)
 }

plugin/errors.go

@@ -5,14 +5,15 @@ import (
 	"fmt"
 )
 
-type Code string
+type ErrorCode string
 
 const (
-	CodeValidation                 Code = "VALIDATION_ERROR"
-	CodeUnsupportedContractVersion Code = "UNSUPPORTED_CONTRACT_VERSION"
-	CodeAccessDenied               Code = "ACCESS_DENIED"
-	CodeThrottled                  Code = "THROTTLED"
-	CodeGeneric                    Code = "ERROR"
+	ErrorCodeValidation                 ErrorCode = "VALIDATION_ERROR"
+	ErrorCodeUnsupportedContractVersion ErrorCode = "UNSUPPORTED_CONTRACT_VERSION"
+	ErrorCodeAccessDenied               ErrorCode = "ACCESS_DENIED"
+	ErrorCodeTimeout                    ErrorCode = "TIMEOUT"
+	ErrorCodeThrottled                  ErrorCode = "THROTTLED"
+	ErrorCodeGeneric                    ErrorCode = "ERROR"
 )
 
 const (
@@ -23,39 +24,40 @@ const (
 // Error is used when the signature associated is no longer
 // valid.
 type Error struct {
-	ErrCode Code   `json:"errorCode"`
-	Msg     string `json:"errorMessage"`
+	ErrCode  ErrorCode         `json:"errorCode"`
+	Message  string            `json:"errorMessage,omitempty"`
+	Metadata map[string]string `json:"errorMetadata,omitempty"`
 }
 
-func NewError(code Code, msg string) *Error {
+func NewError(code ErrorCode, msg string) *Error {
 	return &Error{
 		ErrCode: code,
-		Msg:     msg,
+		Message: msg,
 	}
 }
 
 func NewGenericError(msg string) *Error {
-	return NewError(CodeGeneric, msg)
+	return NewError(ErrorCodeGeneric, msg)
 }
 
 func NewGenericErrorf(format string, msg string) *Error {
-	return NewError(CodeGeneric, fmt.Sprintf(format, msg))
+	return NewError(ErrorCodeGeneric, fmt.Sprintf(format, msg))
 }
 
 func NewUnsupportedError(msg string) *Error {
-	return NewError(CodeValidation, msg+" is not supported")
+	return NewError(ErrorCodeValidation, msg+" is not supported")
 }
 
 func NewValidationError(msg string) *Error {
-	return NewError(CodeValidation, msg)
+	return NewError(ErrorCodeValidation, msg)
 }
 
 func NewValidationErrorf(format string, msg string) *Error {
-	return NewError(CodeValidation, fmt.Sprintf(format, msg))
+	return NewError(ErrorCodeValidation, fmt.Sprintf(format, msg))
 }
 
 func NewUnsupportedContractVersionError(version string) *Error {
-	return NewError(CodeUnsupportedContractVersion, fmt.Sprintf("%q is not a supported notary plugin contract version", version))
+	return NewError(ErrorCodeUnsupportedContractVersion, fmt.Sprintf("%q is not a supported notary plugin contract version", version))
 }
 
 func NewJSONParsingError(msg string) *Error {

plugin/proto.go

@@ -2,6 +2,12 @@
 // and notation external plugin.
 package plugin
 
+// BinaryPrefix is the prefix required on all plugin binary names.
+const BinaryPrefix = "notation-"
+
+// ContractVersion is the <major>.<minor> version of the plugin contract.
+const ContractVersion = "1.0"
+
 // Capability is a feature available in the plugin contract.
 type Capability string
 
@@ -26,6 +32,11 @@ const (
 // Command is a CLI command available in the plugin contract.
 type Command string
 
+// Request defines a plugin request, which is always associated to a command.
+type Request interface {
+	Command() Command
+}
+
 const (
 	// CommandGetMetadata is the name of the plugin command
 	// which must be supported by every plugin and returns the