英文:
CORS failure from Go backend to frontend on docker image
问题
所以我在本地运行一个后端服务器，并在Docker容器中的localhost:8080上运行前端。当我打开前端时，我得到以下错误：
Access to fetch at 'http://localhost:3000/myservice' from origin 'http://localhost:8080' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
我在网上搜索了一下，看到了各种设置头文件的版本。但是没有一个有效。我现在的设置如下：
func (m MyService) initializeRoutes() {
m.router.HandleFunc(VERSION+"/stuff", corsHandler(b.getStuff)).Methods("GET")
}
func corsHandler(h http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
log.Print("preflight detected: ", r.Header)
w.Header().Add("Connection", "keep-alive")
w.Header().Add("Access-Control-Allow-Origin", "*")
w.Header().Add("Access-Control-Allow-Methods", "POST, OPTIONS, GET, DELETE, PUT")
w.Header().Add("Access-Control-Allow-Headers", "content-type")
w.Header().Add("Access-Control-Max-Age", "86400")
// continue with my method
h(w, r)
}
}
func (m MyService) getStuff(w http.ResponseWriter, r *http.Request) {
//Do what is required
}
但是无论我设置什么，我始终得到相同的错误。有人知道为什么会出现这个错误以及如何解决吗？
英文:
So I am running a backend server locally, and the frontend in a Docker container at localhost:8080. When I open the front end, I get:
Access to fetch at 'http://localhost:3000/myservice' from origin 'http://localhost:8080' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
I had a root around online and saw various versions of setting headers. None worked. The one i have now is like this:
func (m MyService) initializeRoutes() {
m.router.HandleFunc(VERSION+"/stuff", corsHandler(b.getStuff)).Methods("GET")
}
func corsHandler(h http.HandlerFunc) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
log.Print("preflight detected: ", r.Header)
w.Header().Add("Connection", "keep-alive")
w.Header().Add("Access-Control-Allow-Origin", "*")
w.Header().Add("Access-Control-Allow-Methods", "POST, OPTIONS, GET, DELETE, PUT")
w.Header().Add("Access-Control-Allow-Headers", "content-type")
w.Header().Add("Access-Control-Max-Age", "86400")
// continue with my method
h(w, r)
}
}
func (m MyService) getStuff(w http.ResponseWriter, r *http.Request) {
//Do what is required
}
But i get the same error from the start no matter what i seem to set. Anyone know why I am getting this and how to fix it?
答案1
得分: 1
创建一个中间件：
func EnableCORS(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Vary", "Origin")
w.Header().Add("Vary", "Access-Control-Request-Method")
if r.Header.Get("Origin") != "" {
w.Header().Set("Access-Control-Allow-Origin", "*")
if isPreflight(r) {
w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, PUT, PATCH, DELETE")
w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
w.WriteHeader(http.StatusOK)
return
}
break
}
next.ServeHTTP(w, r)
})
}
func isPreflight(r *http.Request) bool {
return r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != ""
}
将中间件包装在你的路由器周围：
r := http.NewServeMux()
http.ListenAndServe(":8080", EnableCors(r))
希望能帮到你。
编辑于2023-06-26：
如jub0bs在评论中建议的那样，使用一个维护良好的cors包：
英文:
Create a middleware:
func EnableCORS(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Vary", "Origin")
w.Header().Add("Vary", "Access-Control-Request-Method")
if r.Header.Get("Origin") != "" {
w.Header().Set("Access-Control-Allow-Origin", "*")
if isPreflight(r) {
w.Header().Set("Access-Control-Allow-Methods", "OPTIONS, PUT, PATCH, DELETE")
w.Header().Set("Access-Control-Allow-Headers", "Authorization, Content-Type")
w.WriteHeader(http.StatusOK)
return
}
break
}
next.ServeHTTP(w, r)
})
}
func isPreflight(r *http.Request) bool {
return r.Method == http.MethodOptions && r.Header.Get("Access-Control-Request-Method") != ""
}
Wrap the middleware around your router:
r := http.NewServeMux()
http.ListenAndServe(":8080", EnableCors(r))
Hope that helps.
EDIT 2023-06-26:
As jub0bs recommended in the comments, use a cors package which is maintained like:
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