MINOR: filter: add support for lua filters

Add a new "lua" filter type accepting the "filter lua.<name> [args...]"
directive. This includes the config-parser Lua parser and dispatch, the
specification enum and lua_name/lua_args fields, the regenerated models,
and the configuration CRUD wiring.

Author: Jakub Suchy

config-parser/parsers/filters/filter-lua.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2019 HAProxy Technologies
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package filters
+
+import (
+	"strings"
+
+	"github.com/haproxytech/client-native/v6/config-parser/common"
+	"github.com/haproxytech/client-native/v6/config-parser/errors"
+)
+
+// Lua represents a Lua filter declared with "filter lua.<name> [args...]".
+// The filter keyword is the name registered from Lua via core.register_filter().
+type Lua struct {
+	Name    string
+	Args    []string
+	Comment string
+}
+
+func (f *Lua) Parse(parts []string, comment string) error {
+	if comment != "" {
+		f.Comment = comment
+	}
+	if len(parts) < 2 {
+		return errors.ErrInvalidData
+	}
+	name := strings.TrimPrefix(parts[1], "lua.")
+	if name == "" || name == parts[1] {
+		return errors.ErrInvalidData
+	}
+	f.Name = name
+	if len(parts) > 2 {
+		f.Args = append([]string{}, parts[2:]...)
+	}
+	return nil
+}
+
+func (f *Lua) Result() common.ReturnResultLine {
+	var result strings.Builder
+	result.WriteString("filter lua.")
+	result.WriteString(f.Name)
+	for _, arg := range f.Args {
+		result.WriteString(" ")
+		result.WriteString(arg)
+	}
+	return common.ReturnResultLine{
+		Data:    result.String(),
+		Comment: f.Comment,
+	}
+}

config-parser/parsers/filters/filter.go

@@ -17,6 +17,8 @@ limitations under the License.
 package filters
 
 import (
+	"strings"
+
 	"github.com/haproxytech/client-native/v6/config-parser/common"
 	"github.com/haproxytech/client-native/v6/config-parser/errors"
 	"github.com/haproxytech/client-native/v6/config-parser/types"
@@ -60,7 +62,12 @@ func (h *Filters) Parse(line string, parts []string, comment string) (string, er
 		case "bwlim-in", "bwlim-out":
 			err = h.ParseFilter(&BandwidthLimit{}, parts, comment)
 		default:
-			return "", &errors.ParseError{Parser: "FilterLines", Line: line}
+			// Lua filters use a dynamic keyword "lua.<name>", so they can't be matched as a fixed case above.
+			if strings.HasPrefix(parts[1], "lua.") {
+				err = h.ParseFilter(&Lua{}, parts, comment)
+			} else {
+				return "", &errors.ParseError{Parser: "FilterLines", Line: line}
+			}
 		}
 		if err != nil {
 			return "", err

config-parser/tests/filter_generated_test.go

@@ -209,6 +209,10 @@ type Filter interface {
 //test:ok:filter trace random-forwarding hexdump
 //test:ok:filter trace hexdump
 //test:ok:filter trace
+//test:ok:filter lua.my-filter
+//test:ok:filter lua.my-filter arg1 arg2
+//test:fail:filter lua
+//test:fail:filter lua.
 //test:fail:filter bwlim-in
 //test:fail:filter bwlim-in name
 //test:fail:filter bwlim-in name default-limit

config-parser/types/types-other.go

@@ -323,6 +323,13 @@ func ParseFilter(f types.Filter) *models.Filter {
 			CacheName: v.Name,
 			Metadata:  misc.ParseMetadata(v.Comment),
 		}
+	case *filters.Lua:
+		return &models.Filter{
+			Type:     models.FilterTypeLua,
+			LuaName:  v.Name,
+			LuaArgs:  append([]string{}, v.Args...),
+			Metadata: misc.ParseMetadata(v.Comment),
+		}
 	}
 	return nil
 }
@@ -389,6 +396,12 @@ func SerializeFilter(f models.Filter, opt *options.ConfigurationOptions) types.F
 			Table:         &f.Table,
 			Comment:       comment,
 		}
+	case models.FilterTypeLua:
+		return &filters.Lua{
+			Name:    f.LuaName,
+			Args:    append([]string{}, f.LuaArgs...),
+			Comment: comment,
+		}
 	}
 	return nil
 }

configuration/filter.go

@@ -8078,6 +8078,23 @@ definitions:
               - bwlim-in
               - bwlim-out
         x-size: true
+      lua_args:
+        description: Optional arguments passed to the Lua filter constructor.
+        items:
+          type: string
+        type: array
+        x-dependency:
+          type:
+            value: lua
+        x-omitempty: true
+      lua_name:
+        description: Name of the Lua filter as registered by core.register_filter(), used in the 'filter lua.<name>' directive.
+        pattern: ^[^\s]+$
+        type: string
+        x-dependency:
+          type:
+            required: true
+            value: lua
       metadata:
         additionalProperties:
           type: object
@@ -8152,6 +8169,7 @@ definitions:
           - fcgi-app
           - spoe
           - trace
+          - lua
         type: string
         x-nullable: false
     required: