feat: plugins integration.

pkg/server/middleware/middlewares.go

@@ -28,6 +28,7 @@ import (
 	"github.com/containous/traefik/v2/pkg/middlewares/stripprefix"
 	"github.com/containous/traefik/v2/pkg/middlewares/stripprefixregex"
 	"github.com/containous/traefik/v2/pkg/middlewares/tracing"
+	"github.com/containous/traefik/v2/pkg/plugins"
 	"github.com/containous/traefik/v2/pkg/server/provider"
 )
 
@@ -40,6 +41,7 @@ const (
 // Builder the middleware builder.
 type Builder struct {
 	configs        map[string]*runtime.MiddlewareInfo
+	pluginBuilder  *plugins.Builder
 	serviceBuilder serviceBuilder
 }
 
@@ -48,8 +50,8 @@ type serviceBuilder interface {
 }
 
 // NewBuilder creates a new Builder.
-func NewBuilder(configs map[string]*runtime.MiddlewareInfo, serviceBuilder serviceBuilder) *Builder {
-	return &Builder{configs: configs, serviceBuilder: serviceBuilder}
+func NewBuilder(configs map[string]*runtime.MiddlewareInfo, serviceBuilder serviceBuilder, pluginBuilder *plugins.Builder) *Builder {
+	return &Builder{configs: configs, serviceBuilder: serviceBuilder, pluginBuilder: pluginBuilder}
 }
 
 // BuildChain creates a middleware chain.
@@ -338,6 +340,27 @@ func (b *Builder) buildConstructor(ctx context.Context, middlewareName string) (
 		}
 	}
 
+	// Plugin
+	if config.Plugin != nil {
+		if middleware != nil {
+			return nil, badConf
+		}
+
+		pluginType, rawPluginConfig, err := findPluginConfig(config.Plugin)
+		if err != nil {
+			return nil, err
+		}
+
+		m, err := b.pluginBuilder.Build(pluginType, rawPluginConfig, middlewareName)
+		if err != nil {
+			return nil, err
+		}
+
+		middleware = func(next http.Handler) (http.Handler, error) {
+			return m.NewHandler(ctx, next)
+		}
+	}
+
 	if middleware == nil {
 		return nil, fmt.Errorf("invalid middleware %q configuration: invalid middleware type or middleware does not exist", middlewareName)
 	}

pkg/server/middleware/middlewares_test.go

@@ -18,7 +18,7 @@ func TestBuilder_BuildChainNilConfig(t *testing.T) {
 	testConfig := map[string]*runtime.MiddlewareInfo{
 		"empty": {},
 	}
-	middlewaresBuilder := NewBuilder(testConfig, nil)
+	middlewaresBuilder := NewBuilder(testConfig, nil, nil)
 
 	chain := middlewaresBuilder.BuildChain(context.Background(), []string{"empty"})
 	_, err := chain.Then(nil)
@@ -29,7 +29,7 @@ func TestBuilder_BuildChainNonExistentChain(t *testing.T) {
 	testConfig := map[string]*runtime.MiddlewareInfo{
 		"foobar": {},
 	}
-	middlewaresBuilder := NewBuilder(testConfig, nil)
+	middlewaresBuilder := NewBuilder(testConfig, nil, nil)
 
 	chain := middlewaresBuilder.BuildChain(context.Background(), []string{"empty"})
 	_, err := chain.Then(nil)
@@ -270,7 +270,7 @@ func TestBuilder_BuildChainWithContext(t *testing.T) {
 					Middlewares: test.configuration,
 				},
 			})
-			builder := NewBuilder(rtConf.Middlewares, nil)
+			builder := NewBuilder(rtConf.Middlewares, nil, nil)
 
 			result := builder.BuildChain(ctx, test.buildChain)
 
@@ -329,7 +329,7 @@ func TestBuilder_buildConstructor(t *testing.T) {
 			Middlewares: testConfig,
 		},
 	})
-	middlewaresBuilder := NewBuilder(rtConf.Middlewares, nil)
+	middlewaresBuilder := NewBuilder(rtConf.Middlewares, nil, nil)
 
 	testCases := []struct {
 		desc          string

pkg/server/middleware/plugins.go

@@ -0,0 +1,32 @@
+package middleware
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/containous/traefik/v2/pkg/config/dynamic"
+)
+
+func findPluginConfig(rawConfig map[string]dynamic.PluginConf) (string, map[string]interface{}, error) {
+	if len(rawConfig) != 1 {
+		return "", nil, errors.New("plugin: invalid configuration: no configuration or too many plugin definition")
+	}
+
+	var pluginType string
+	var rawPluginConfig map[string]interface{}
+
+	for pType, pConfig := range rawConfig {
+		pluginType = pType
+		rawPluginConfig = pConfig
+	}
+
+	if pluginType == "" {
+		return "", nil, errors.New("plugin: missing plugin type")
+	}
+
+	if len(rawPluginConfig) == 0 {
+		return "", nil, fmt.Errorf("plugin: missing plugin configuration: %s", pluginType)
+	}
+
+	return pluginType, rawPluginConfig, nil
+}