pixiu/pkg/filter/http/loadbalancer/loadbalancer.go

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 loadbalancer

import (
	"math/rand"
	"strings"
)

import (
	"github.com/apache/dubbo-go-pixiu/pixiu/pkg/common/constant"
	"github.com/apache/dubbo-go-pixiu/pixiu/pkg/common/extension/filter"
	contexthttp "github.com/apache/dubbo-go-pixiu/pixiu/pkg/context/http"
)

const (
	Kind = constant.HTTPLoadBalanceFilter
)

func init() {
	filter.RegisterHttpFilter(&Plugin{})
}

type (
	// Plugin is http filter plugin.
	Plugin struct {
	}

	// FilterFactory is http filter instance
	FilterFactory struct {
		cfg *Config
	}
	// Filter is http filter instance
	Filter struct {
		cfg *Config
	}
	Config struct{}
)

func (p *Plugin) Kind() string {
	return Kind
}

func (p *Plugin) CreateFilterFactory() (filter.HttpFilterFactory, error) {
	return &FilterFactory{cfg: &Config{}}, nil
}

func (factory *FilterFactory) Config() interface{} {
	return factory.cfg
}

func (factory *FilterFactory) Apply() error {
	return nil
}

func (factory *FilterFactory) PrepareFilterChain(ctx *contexthttp.HttpContext, chain filter.FilterChain) error {
	f := &Filter{cfg: factory.cfg}
	chain.AppendDecodeFilters(f)
	return nil
}

func (f *Filter) Decode(c *contexthttp.HttpContext) filter.FilterStatus {
	allInstances := strings.Split(c.GetAPI().IntegrationRequest.HTTPBackendConfig.URL, ",")
	idx := rand.Int31n(int32(len(allInstances)))
	c.Api.IntegrationRequest.HTTPBackendConfig.URL = strings.TrimSpace(allInstances[idx])
	return filter.Continue
}