Add http-wasm plugin support to Traefik

pkg/plugins/middlewareyaegi.go

@@ -0,0 +1,146 @@
+package plugins
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"os"
+	"path"
+	"reflect"
+	"strings"
+
+	"github.com/mitchellh/mapstructure"
+	"github.com/rs/zerolog"
+	"github.com/rs/zerolog/log"
+	"github.com/traefik/traefik/v3/pkg/logs"
+	"github.com/traefik/yaegi/interp"
+	"github.com/traefik/yaegi/stdlib"
+)
+
+type yaegiMiddlewareBuilder struct {
+	fnNew          reflect.Value
+	fnCreateConfig reflect.Value
+}
+
+func newYaegiMiddlewareBuilder(i *interp.Interpreter, basePkg, imp string) (*yaegiMiddlewareBuilder, error) {
+	if basePkg == "" {
+		basePkg = strings.ReplaceAll(path.Base(imp), "-", "_")
+	}
+
+	fnNew, err := i.Eval(basePkg + `.New`)
+	if err != nil {
+		return nil, fmt.Errorf("failed to eval New: %w", err)
+	}
+
+	fnCreateConfig, err := i.Eval(basePkg + `.CreateConfig`)
+	if err != nil {
+		return nil, fmt.Errorf("failed to eval CreateConfig: %w", err)
+	}
+
+	return &yaegiMiddlewareBuilder{
+		fnNew:          fnNew,
+		fnCreateConfig: fnCreateConfig,
+	}, nil
+}
+
+func (b yaegiMiddlewareBuilder) newMiddleware(config map[string]interface{}, middlewareName string) (pluginMiddleware, error) {
+	vConfig, err := b.createConfig(config)
+	if err != nil {
+		return nil, err
+	}
+
+	return &YaegiMiddleware{
+		middlewareName: middlewareName,
+		config:         vConfig,
+		builder:        b,
+	}, nil
+}
+
+func (b yaegiMiddlewareBuilder) newHandler(ctx context.Context, next http.Handler, cfg reflect.Value, middlewareName string) (http.Handler, error) {
+	args := []reflect.Value{reflect.ValueOf(ctx), reflect.ValueOf(next), cfg, reflect.ValueOf(middlewareName)}
+	results := b.fnNew.Call(args)
+
+	if len(results) > 1 && results[1].Interface() != nil {
+		err, ok := results[1].Interface().(error)
+		if !ok {
+			return nil, fmt.Errorf("invalid error type: %T", results[0].Interface())
+		}
+
+		return nil, err
+	}
+
+	handler, ok := results[0].Interface().(http.Handler)
+	if !ok {
+		return nil, fmt.Errorf("invalid handler type: %T", results[0].Interface())
+	}
+
+	return handler, nil
+}
+
+func (b yaegiMiddlewareBuilder) createConfig(config map[string]interface{}) (reflect.Value, error) {
+	results := b.fnCreateConfig.Call(nil)
+	if len(results) != 1 {
+		return reflect.Value{}, fmt.Errorf("invalid number of return for the CreateConfig function: %d", len(results))
+	}
+
+	vConfig := results[0]
+	if len(config) == 0 {
+		return vConfig, nil
+	}
+
+	cfg := &mapstructure.DecoderConfig{
+		DecodeHook:       mapstructure.StringToSliceHookFunc(","),
+		WeaklyTypedInput: true,
+		Result:           vConfig.Interface(),
+	}
+
+	decoder, err := mapstructure.NewDecoder(cfg)
+	if err != nil {
+		return reflect.Value{}, fmt.Errorf("failed to create configuration decoder: %w", err)
+	}
+
+	err = decoder.Decode(config)
+	if err != nil {
+		return reflect.Value{}, fmt.Errorf("failed to decode configuration: %w", err)
+	}
+
+	return vConfig, nil
+}
+
+// YaegiMiddleware is an HTTP handler plugin wrapper.
+type YaegiMiddleware struct {
+	middlewareName string
+	config         reflect.Value
+	builder        yaegiMiddlewareBuilder
+}
+
+// NewHandler creates a new HTTP handler.
+func (m *YaegiMiddleware) NewHandler(ctx context.Context, next http.Handler) (http.Handler, error) {
+	return m.builder.newHandler(ctx, next, m.config, m.middlewareName)
+}
+
+func newInterpreter(ctx context.Context, goPath string, manifestImport string) (*interp.Interpreter, error) {
+	i := interp.New(interp.Options{
+		GoPath: goPath,
+		Env:    os.Environ(),
+		Stdout: logs.NoLevel(*log.Ctx(ctx), zerolog.DebugLevel),
+		Stderr: logs.NoLevel(*log.Ctx(ctx), zerolog.ErrorLevel),
+	})
+
+	err := i.Use(stdlib.Symbols)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load symbols: %w", err)
+	}
+
+	err = i.Use(ppSymbols())
+	if err != nil {
+		return nil, fmt.Errorf("failed to load provider symbols: %w", err)
+	}
+
+	_, err = i.Eval(fmt.Sprintf(`import "%s"`, manifestImport))
+	if err != nil {
+		return nil, fmt.Errorf("failed to import plugin code %q: %w", manifestImport, err)
+	}
+
+	return i, nil
+}