174 lines
4.8 KiB
Go
174 lines
4.8 KiB
Go
package plugins
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import (
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"context"
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"fmt"
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"net/http"
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"path"
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"reflect"
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"strings"
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"github.com/mitchellh/mapstructure"
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"github.com/traefik/yaegi/interp"
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"github.com/traefik/yaegi/stdlib"
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)
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const devPluginName = "dev"
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// Constructor creates a plugin handler.
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type Constructor func(context.Context, http.Handler) (http.Handler, error)
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// pluginContext The static part of a plugin configuration.
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type pluginContext struct {
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// GoPath plugin's GOPATH
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GoPath string `json:"goPath,omitempty" toml:"goPath,omitempty" yaml:"goPath,omitempty"`
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// Import plugin's import/package
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Import string `json:"import,omitempty" toml:"import,omitempty" yaml:"import,omitempty"`
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// BasePkg plugin's base package name (optional)
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BasePkg string `json:"basePkg,omitempty" toml:"basePkg,omitempty" yaml:"basePkg,omitempty"`
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interpreter *interp.Interpreter
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}
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// Builder is a plugin builder.
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type Builder struct {
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descriptors map[string]pluginContext
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}
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// NewBuilder creates a new Builder.
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func NewBuilder(client *Client, plugins map[string]Descriptor, devPlugin *DevPlugin) (*Builder, error) {
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pb := &Builder{
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descriptors: map[string]pluginContext{},
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}
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for pName, desc := range plugins {
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manifest, err := client.ReadManifest(desc.ModuleName)
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if err != nil {
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_ = client.ResetAll()
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return nil, fmt.Errorf("%s: failed to read manifest: %w", desc.ModuleName, err)
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}
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i := interp.New(interp.Options{GoPath: client.GoPath()})
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i.Use(stdlib.Symbols)
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_, err = i.Eval(fmt.Sprintf(`import "%s"`, manifest.Import))
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if err != nil {
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return nil, fmt.Errorf("%s: failed to import plugin code %q: %w", desc.ModuleName, manifest.Import, err)
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}
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pb.descriptors[pName] = pluginContext{
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interpreter: i,
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GoPath: client.GoPath(),
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Import: manifest.Import,
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BasePkg: manifest.BasePkg,
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}
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}
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if devPlugin != nil {
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manifest, err := ReadManifest(devPlugin.GoPath, devPlugin.ModuleName)
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if err != nil {
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return nil, fmt.Errorf("%s: failed to read manifest: %w", devPlugin.ModuleName, err)
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}
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i := interp.New(interp.Options{GoPath: devPlugin.GoPath})
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i.Use(stdlib.Symbols)
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_, err = i.Eval(fmt.Sprintf(`import "%s"`, manifest.Import))
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if err != nil {
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return nil, fmt.Errorf("%s: failed to import plugin code %q: %w", devPlugin.ModuleName, manifest.Import, err)
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}
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pb.descriptors[devPluginName] = pluginContext{
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interpreter: i,
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GoPath: devPlugin.GoPath,
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Import: manifest.Import,
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BasePkg: manifest.BasePkg,
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}
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}
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return pb, nil
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}
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// Build builds a plugin.
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func (b Builder) Build(pName string, config map[string]interface{}, middlewareName string) (Constructor, error) {
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if b.descriptors == nil {
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return nil, fmt.Errorf("plugin: no plugin definition in the static configuration: %s", pName)
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}
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descriptor, ok := b.descriptors[pName]
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if !ok {
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return nil, fmt.Errorf("plugin: unknown plugin type: %s", pName)
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}
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m, err := newMiddleware(descriptor, config, middlewareName)
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if err != nil {
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return nil, err
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}
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return m.NewHandler, err
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}
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// Middleware is a HTTP handler plugin wrapper.
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type Middleware struct {
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middlewareName string
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fnNew reflect.Value
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config reflect.Value
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}
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func newMiddleware(descriptor pluginContext, config map[string]interface{}, middlewareName string) (*Middleware, error) {
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basePkg := descriptor.BasePkg
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if basePkg == "" {
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basePkg = strings.ReplaceAll(path.Base(descriptor.Import), "-", "_")
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}
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vConfig, err := descriptor.interpreter.Eval(basePkg + `.CreateConfig()`)
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if err != nil {
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return nil, fmt.Errorf("plugin: failed to eval CreateConfig: %w", err)
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}
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cfg := &mapstructure.DecoderConfig{
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DecodeHook: mapstructure.StringToSliceHookFunc(","),
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WeaklyTypedInput: true,
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Result: vConfig.Interface(),
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}
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decoder, err := mapstructure.NewDecoder(cfg)
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if err != nil {
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return nil, fmt.Errorf("plugin: failed to create configuration decoder: %w", err)
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}
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err = decoder.Decode(config)
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if err != nil {
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return nil, fmt.Errorf("plugin: failed to decode configuration: %w", err)
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}
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fnNew, err := descriptor.interpreter.Eval(basePkg + `.New`)
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if err != nil {
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return nil, fmt.Errorf("plugin: failed to eval New: %w", err)
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}
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return &Middleware{
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middlewareName: middlewareName,
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fnNew: fnNew,
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config: vConfig,
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}, nil
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}
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// NewHandler creates a new HTTP handler.
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func (m *Middleware) NewHandler(ctx context.Context, next http.Handler) (http.Handler, error) {
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args := []reflect.Value{reflect.ValueOf(ctx), reflect.ValueOf(next), m.config, reflect.ValueOf(m.middlewareName)}
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results := m.fnNew.Call(args)
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if len(results) > 1 && results[1].Interface() != nil {
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return nil, results[1].Interface().(error)
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}
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handler, ok := results[0].Interface().(http.Handler)
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if !ok {
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return nil, fmt.Errorf("plugin: invalid handler type: %T", results[0].Interface())
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}
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return handler, nil
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}
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