Implement plugin manager (#37)

* implement plugin manager
* ignore symlinks
* fix Manager.Command
* export constants
* improve error message
* move manager to its own package
* change metadata error messages
* improve the plugin manager interface
* improve Manager.Run
* pr feedback
* remove Command.Capability() and Command.NewResponse()
* remove command validation
* ignore symlinked plugin directories

Signed-off-by: qmuntal <qmuntaldiaz@microsoft.com>

plugin/errors.go

@@ -0,0 +1,74 @@
+package plugin
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+)
+
+type ErrorCode string
+
+const (
+	// Any of the required request fields was empty,
+	// or a value was malformed/invalid.
+	ErrorCodeValidation ErrorCode = "VALIDATION_ERROR"
+
+	// The contract version used in the request is unsupported.
+	ErrorCodeUnsupportedContractVersion ErrorCode = "UNSUPPORTED_CONTRACT_VERSION"
+
+	// Authentication/authorization error to use given key.
+	ErrorCodeAccessDenied ErrorCode = "ACCESS_DENIED"
+
+	// The operation to generate signature timed out
+	// and can be retried by Notation.
+	ErrorCodeTimeout ErrorCode = "TIMEOUT"
+
+	// The operation to generate signature was throttles
+	// and can be retried by Notation.
+	ErrorCodeThrottled ErrorCode = "THROTTLED"
+
+	// Any general error that does not fall into any categories.
+	ErrorCodeGeneric ErrorCode = "ERROR"
+)
+
+type jsonErr struct {
+	Code     ErrorCode         `json:"errorCode"`
+	Message  string            `json:"errorMessage,omitempty"`
+	Metadata map[string]string `json:"errorMetadata,omitempty"`
+}
+
+// RequestError is the common error response for any request.
+type RequestError struct {
+	Code     ErrorCode
+	Err      error
+	Metadata map[string]string
+}
+
+func (e RequestError) Error() string {
+	return fmt.Sprintf("%s: %v", e.Code, e.Err)
+}
+
+func (e RequestError) Unwrap() error {
+	return e.Err
+}
+
+func (e RequestError) MarshalJSON() ([]byte, error) {
+	var msg string
+	if e.Err != nil {
+		msg = e.Err.Error()
+	}
+	return json.Marshal(jsonErr{e.Code, msg, e.Metadata})
+}
+
+func (e *RequestError) UnmarshalJSON(data []byte) error {
+	var tmp jsonErr
+	err := json.Unmarshal(data, &tmp)
+	if err != nil {
+		return err
+	}
+	if tmp.Code == "" && tmp.Message == "" && tmp.Metadata == nil {
+		return errors.New("incomplete json")
+	}
+	*e = RequestError{tmp.Code, errors.New(tmp.Message), tmp.Metadata}
+	return nil
+}

plugin/errors_test.go

@@ -0,0 +1,90 @@
+package plugin
+
+import (
+	"encoding/json"
+	"errors"
+	"reflect"
+	"testing"
+)
+
+func TestRequestError_Error(t *testing.T) {
+	err := RequestError{Code: ErrorCodeAccessDenied, Err: errors.New("an error")}
+	want := string(ErrorCodeAccessDenied) + ": an error"
+	if got := err.Error(); got != want {
+		t.Errorf("RequestError.Error() = %v, want %v", got, want)
+	}
+}
+
+func TestRequestError_Unwrap(t *testing.T) {
+	want := errors.New("an error")
+	got := RequestError{Code: ErrorCodeAccessDenied, Err: want}.Unwrap()
+	if got != want {
+		t.Errorf("RequestError.Unwrap() = %v, want %v", got, want)
+	}
+}
+
+func TestRequestError_MarshalJSON(t *testing.T) {
+	tests := []struct {
+		name string
+		e    RequestError
+		want []byte
+	}{
+		{"empty", RequestError{}, []byte("{\"errorCode\":\"\"}")},
+		{"with code", RequestError{Code: ErrorCodeAccessDenied}, []byte("{\"errorCode\":\"ACCESS_DENIED\"}")},
+		{"with message", RequestError{Code: ErrorCodeAccessDenied, Err: errors.New("failed")}, []byte("{\"errorCode\":\"ACCESS_DENIED\",\"errorMessage\":\"failed\"}")},
+		{
+			"with metadata",
+			RequestError{Code: ErrorCodeAccessDenied, Err: errors.New("failed"), Metadata: map[string]string{"a": "b"}},
+			[]byte("{\"errorCode\":\"ACCESS_DENIED\",\"errorMessage\":\"failed\",\"errorMetadata\":{\"a\":\"b\"}}"),
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.e.MarshalJSON()
+			if err != nil {
+				t.Fatalf("RequestError.MarshalJSON() error = %v, wantErr false", err)
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("RequestError.MarshalJSON() = %s, want %s", got, tt.want)
+			}
+			if tt.e.Code == "" {
+				return
+			}
+			var got1 RequestError
+			err = json.Unmarshal(got, &got1)
+			if err != nil {
+				t.Fatalf("RequestError.UnmarshalJSON() error = %v, wantErr false", err)
+			}
+			if got1.Code != tt.e.Code || !reflect.DeepEqual(got1.Metadata, tt.e.Metadata) {
+				t.Fatalf("RequestError.UnmarshalJSON() = %s, want %s", got1, tt.e)
+			}
+		})
+	}
+}
+
+func TestRequestError_UnmarshalJSON(t *testing.T) {
+	type args struct {
+		data []byte
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    RequestError
+		wantErr bool
+	}{
+		{"invalid", args{[]byte("")}, RequestError{}, true},
+		{"empty", args{[]byte("{}")}, RequestError{}, true},
+		{"with code", args{[]byte("{\"errorCode\":\"ACCESS_DENIED\"}")}, RequestError{Code: ErrorCodeAccessDenied}, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var e RequestError
+			if err := e.UnmarshalJSON(tt.args.data); (err != nil) != tt.wantErr {
+				t.Errorf("RequestError.UnmarshalJSON() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			if !tt.wantErr && (e.Code != tt.want.Code || !reflect.DeepEqual(e.Metadata, tt.want.Metadata)) {
+				t.Fatalf("RequestError.UnmarshalJSON() = %s, want %s", e, tt.want)
+			}
+		})
+	}
+}

plugin/manager/integration_test.go

@@ -0,0 +1,78 @@
+package manager
+
+import (
+	"context"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"reflect"
+	"testing"
+
+	"github.com/notaryproject/notation-go/plugin"
+)
+
+func preparePlugin(t *testing.T) string {
+	root := t.TempDir()
+	src, err := os.Open("./testdata/main.go")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer src.Close()
+
+	dst, err := os.Create(filepath.Join(root, "main.go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer dst.Close()
+	_, err = io.Copy(dst, src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = os.WriteFile(filepath.Join(root, "go.mod"), []byte("module main"), 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = os.Mkdir(filepath.Join(root, "foo"), 0755)
+	if err != nil {
+		t.Fatal(err)
+	}
+	out := filepath.Join(root, "foo", plugin.Prefix+"foo")
+	out = addExeSuffix(out)
+	cmd := exec.Command("go", "build", "-o", out)
+	cmd.Dir = root
+	err = cmd.Run()
+	if err != nil {
+		t.Fatal(err)
+	}
+	return root
+}
+
+func TestIntegration(t *testing.T) {
+	if _, err := exec.LookPath("go"); err != nil {
+		t.Skip()
+	}
+	root := preparePlugin(t)
+	mgr := &Manager{rootedFS{os.DirFS(root), root}, execCommander{}}
+	p, err := mgr.Get(context.Background(), "foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if p.Err != nil {
+		t.Fatal(p.Err)
+	}
+	list, err := mgr.List(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(list) != 1 {
+		t.Fatalf("Manager.List() len got %d, want 1", len(list))
+	}
+	if !reflect.DeepEqual(list[0].Metadata, p.Metadata) {
+		t.Errorf("Manager.List() got %v, want %v", list[0], p)
+	}
+	_, err = mgr.Run(context.Background(), "foo", plugin.CommandGetMetadata, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+}