开发笔记:如何使用Golang实现一个API网关

{
"upstreams": [
{
"upstream": "http://api.qingyunke.com",
"path": "/jiqieren/",
"trim_path": true,
"is_auth": true
}
],
...
}

{
...
"auth_items": {
"Bearer": {
"oauth_type": "BearerConfig",
"configs": {
"file": "bearer.json"
}
}
}
}

{
"GnPIymAqtPEodx2di0cS9o1GP9QEM2N2-Ur_5ggvANwSKRewH2DLmw": {
"interfaces": [
"/jiqieren/api.php"
],
"headers": {
"TenantId": "100860"
}
}
}

package main
import (
"./Configs"
"./Server"
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"log"
"net/http"
"net/http/httputil"
"net/url"
"os"
"strings"
)
func main() {
var port int
var config string
flag.IntVar(&port, "port", 80, "server port")
flag.StringVar(&config, "config", "", "mapping config")
flag.Parse()
if cOnfig== "" {
log.Fatal("not found config")
}
if fileExist(config) == false {
log.Fatal("not found config file")
}
data, err := ioutil.ReadFile(config)
if err != nil {
log.Fatal(err)
}
var configInstance Configs.Config
err = json.Unmarshal(data, &configInstance)
if err != nil {
log.Fatal(err)
}
auths := make(map[string]Server.IAuthInterface)
if configInstance.AuthItems != nil {
for name, configItem := range configInstance.AuthItems {
auth_item := Server.GetAuthFactoryInstance().CreateAuthInstance(configItem.OAuthType)
if auth_item == nil {
continue
}
auth_item.InitWithConfig(configItem.Configs)
auths[strings.ToLower(name)] = auth_item
log.Println(name, configItem)
}
}
for i := 0; i {
up := configInstance.Upstreams[i]
u, err := url.Parse(up.Upstream)
log.Printf("{%s} => {%s}
", up.Application, up.Upstream)
if err != nil {
log.Fatal(err)
}
rp := httputil.NewSingleHostReverseProxy(u)
http.HandleFunc(up.Application, func(writer http.ResponseWriter, request *http.Request) {
o_path := request.URL.Path
if up.UpHost != "" {
request.Host = up.UpHost
} else {
request.Host = u.Host
}
if up.TrimApplication {
request.URL.Path = strings.TrimPrefix(request.URL.Path, up.Application)
}
if up.IsAuth {
auth_value := request.Header.Get("Authorization")
if auth_value == "" {
writeUnAuthorized(writer)
return
}
sp_index := strings.Index(auth_value, " ")
auth_type := auth_value[:sp_index]
auth_token := auth_value[sp_index+1:]
if auth_instance, ok := auths[strings.ToLower(auth_type)]; ok {
err, headers := auth_instance.GetAuthInfo(auth_token, o_path)
if err != nil {
writeUnAuthorized(writer)
} else {
if headers != nil {
for k, v := range headers {
request.Header.Add(k, v)
}
}
rp.ServeHTTP(writer, request)
}
} else {
writeUnsupportedAuthType(writer)
}
} else {
rp.ServeHTTP(writer, request)
}
})
}
log.Printf("http server start on :%d
", port)
http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
log.Println("finsh")
}
func writeUnsupportedAuthType(writer http.ResponseWriter) () {
writer.Header().Add("Content-Type", "Application/json")
writer.WriteHeader(http.StatusBadRequest)
writer.Write([]byte("{"status":"unsupported authorization"}"))
}
func writeUnAuthorized(writer http.ResponseWriter) {
writer.Header().Add("Content-Type", "Application/json")
writer.WriteHeader(http.StatusUnauthorized)
writer.Write([]byte("{"status":"un-authorized"}"))
}
func fileExist(filename string) bool {
_, err := os.Stat(filename)
return err == nil || os.IsExist(err)
}

package Server
import (
"log"
"strings"
)
type IAuthInterface interface {
GetAuthInfo(token string, url string) (err error, headers map[string]string)
InitWithConfig(config map[string]string)
}
type AuthFactory struct {
}
var auth_factory_instance AuthFactory
func init() {
auth_factory_instance = AuthFactory{}
}
func GetAuthFactoryInstance() *AuthFactory {
return &auth_factory_instance
}
func (this *AuthFactory) CreateAuthInstance(t string) IAuthInterface {
if strings.ToLower(t) == "bearer" {
return &BeareAuth{}
}
if strings.ToLower(t) == "bearerconfig" {
return &BearerConfigAuth{}
}
log.Fatalf("%s 是不支持的类型
", t)
return nil
}

package Server
import (
"encoding/json"
"errors"
"io/ioutil"
"log"
)
type BearerConfigItem struct {
Headers map[string]string `json:"headers"`
Interfaces []string `json:"interfaces"`
}
type BearerConfigAuth struct {
Configs map[string]*BearerConfigItem // token =》 config item
}
func (this *BearerConfigAuth) GetAuthInfo(token string, url string) (err error, headers map[string]string) {
configItem := this.Configs[token]
if cOnfigItem== nil {
err = errors.New("not found token")
return
}
if IndexOf(configItem.Interfaces, url) == -1 {
err = errors.New("un-authorized")
return
}
headers = make(map[string]string)
for k, v := range configItem.Headers {
headers[k] = v
}
return
}
func (this *BearerConfigAuth) InitWithConfig(config map[string]string) {
cFile := config["file"]
if cFile == "" {
return
}
data, err := ioutil.ReadFile(cFile)
if err != nil {
log.Panic(err)
}
var m map[string]*BearerConfigItem
//this.COnfigs= make(map[string]*BearerConfigItem)
err = json.Unmarshal(data, &m)
if err != nil {
log.Panic(err)
}
this.COnfigs= m
}
func IndexOf(array []string, item string) int {
for i := 0; i {
if array[i] == item {
return i
}
}
return -1
}