更详细的信息，请移步Blog《谈谈Pixiu的Filter》
我们来尝试写一个简单的Filter，这个Filter将会有简单的配置，在Decode阶段把请求的Body Log出来，并翻转后作为Mock的返回值。最后在Encode阶段根据配置把返回值Log出来。
1.首先创建一个Filter
type DemoFilter struct {
logPrefix string
}
// Decode阶段，发生在调用Upstream之前
func (f *DemoFilter) Decode(ctx *contexthttp.HttpContext) filter.FilterStatus {
body, _ := ioutil.ReadAll(ctx.Request.Body)
logger.Infof("request body: %s", body)
//reverse res str
runes := []rune(string(body))
for i := 0; i < len(runes)/2; i += 1 {
runes[i], runes[len(runes)-1-i] = runes[len(runes)-1-i], runes[i]
}
reverse := string(runes)
//mock response
ctx.SendLocalReply(200, []byte(reverse))
return filter.Stop
}
// Encode阶段，此时可以获取到Upstream的Response
func (f *DemoFilter) Encode(ctx *contexthttp.HttpContext) filter.FilterStatus {
res := ctx.SourceResp.(string)
logger.Infof("%s: %s", f.logPrefix, res)
return filter.Continue
}
2.创建Filter Factory
type (
DemoFilterFactory struct {
conf *Config
}
// Config describe the config of Filter
Config struct {
LogPrefix string `yaml:"logPrefix,omitempty"`
}
)
func (f *DemoFilterFactory) PrepareFilterChain(ctx *contexthttp.HttpContext, chain filter.FilterChain) error {
demo := &DemoFilter{logPrefix: f.conf.LogPrefix}
chain.AppendDecodeFilters(demo)
chain.AppendEncodeFilters(demo)
return nil
}
func (f *DemoFilterFactory) Config() interface{} {
return f.conf
}
func (f *DemoFilterFactory) Apply() error {
return nil
}
3.创建Filter Plugin，并注册自己
//important
func init() {
filter.RegisterHttpFilter(&Plugin{})
}
type Plugin struct {
}
func (p *Plugin) Kind() string {
return "dgp.filters.demo"
}
func (p *Plugin) CreateFilterFactory() (filter.HttpFilterFactory, error) {
return &DemoFilterFactory{conf: &Config{}}, nil
}
4.配置文件中配置此Filter，并启动Pixiu
static_resources:
listeners:
- name: "net/http"
protocol_type: "HTTP"
address:
socket_address:
address: "0.0.0.0"
port: 8888
filter_chains:
filters:
- name: dgp.filter.httpconnectionmanager
config:
route_config:
routes:
- match:
prefix: "/"
http_filters:
- name: dgp.filters.demo
config:
5.访问并查看日志与结果
curl localhost:8888/demo -d "eiv al tse’c"
c’est la vie%
日志
2022-02-19T20:20:11.900+0800 INFO demo/demo.go:62 request body: eiv al tse’c
2022-02-19T20:20:11.900+0800 INFO demo/demo.go:71 : eiv al tse’c