Kratos配置允许跨域请求

写法一 kratos官方实现

kratos官方示例
StackOverflow上的讨论
编写文档时kratos版本为v2.7.0

import (
	...
	"github.com/go-kratos/kratos/v2/transport/http"
	"github.com/gorilla/handlers"
)

func NewHTTPServer(...) *http.Server {
    
    
	var opts = []http.ServerOption{
    
    
		http.Middleware(
			...,
		),
	}
	opts = append(opts, http.Network("0.0.0.0"))
	opts = append(opts, http.Address("8080"))
	opts = append(opts, http.Timeout(...))
	
	opts = append(opts, http.Filter(handlers.CORS(
		handlers.AllowedOrigins([]string{
    
    "*"}),
		handlers.AllowedMethods([]string{
    
    "GET", "POST"}),
		handlers.AllowedHeaders([]string{
    
    "Content-Type", "Authorization"}),
	)))

	srv := http.NewServer(opts...)
	xxx.RegisterxxxHTTPServer(srv, xxx)
	return srv
}

注意事项：

• AllowedMethods 不需要显式包含OPTIONS，这是 CORS 处理程序的一部分；
• AllowedHeaders的*不是有效的通配符，gorilla框架没有实现。Content-Type是发送json请求时用到的请求头，Authorization是进行权限认证时用到的请求头，都加上；
• *是AllowedOrigin的默认值。

写法二 基于kratos中间件

中间件代码：

//MiddlewareCors 设置跨域请求头
func MiddlewareCors() middleware.Middleware {
    
    
	return func(handler middleware.Handler) middleware.Handler {
    
    
		return func(ctx context.Context, req interface{
    
    }) (interface{
    
    }, error) {
    
    
			if ts, ok := transport.FromServerContext(ctx); ok {
    
    
				if ht, ok := tr.(http.Transporter); ok {
    
    
					ht.ReplyHeader().Set("Access-Control-Allow-Origin", "*")
					ht.ReplyHeader().Set("Access-Control-Allow-Methods", "GET,POST,OPTIONS,PUT,PATCH,DELETE")
					ht.ReplyHeader().Set("Access-Control-Allow-Credentials", "true")
					ht.ReplyHeader().Set("Access-Control-Allow-Headers", "Content-Type,"+
					   "X-Requested-With,Access-Control-Allow-Credentials,User-Agent,Content-Length,Authorization")
				}
			return handler(ctx, req)
		}
	}
}

注册中间件

func NewHTTPServer(...) *http.Server {
    
    
	var opts = []http.ServerOption{
    
    
		http.Middleware(
			...,
			//注册中间件
			selector.Server(MiddlewareCors()).Build(),
			...,
		),
	}
	opts = append(opts, http.Network("0.0.0.0"))
	opts = append(opts, http.Address("8080"))
	opts = append(opts, http.Timeout(...)

	srv := http.NewServer(opts...)
	xxx.RegisterxxxHTTPServer(srv, xxx)
	return srv
}