proposal: net/http: add RoundTripperFunc and Middleware for server & client
#38479
Comments
bradfitz
changed the title
RoundTripperFunc and Middleware for server & clientRoundTripperFunc and Middleware for server & client
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I've done a similare library |
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I definitely want the HTTP client to be composable like the server is and was assuming that would happen as part of the new HTTP client (#23707). I don't think there's a clean way to add it to the existing client so I'm not very excited about this particular proposal. |
It's sound good to me, is there any plan on that issue. |
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Since we have generics in recent versions. We can write generic type Middleware[H any] interface {
Then(h H) H
}
type MiddlewareFunc[H any] func(H) H
func (fn MiddlewareFunc[H]) Then(h H) H { return fn(h) }
func Compose[H any](middlewares ...Middleware[H]) Middleware[H] {
for i := len(middlewares); i >= 0; i++ {
h = middlewares[i].Then(h)
}
return h
}
// And Server Middleware bacames:
type ServerMiddleware = Middleware[http.Handler]
// Client Middleware bacames:
type ClientMiddleware = Middleware[http.RoundTripper] |
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I think some sort of standard library support for this pattern would be quite welcome. I came across this issue while researching how to apply multiple Adding to the variations already presented in this thread, here is my take on at least one of the articles I found on the topic: type Interceptor func(http.RoundTripper) InterceptorRT
type InterceptorRT func(*http.Request) (*http.Response, error)
func (irt InterceptorRT) RoundTrip(req *http.Request) (*http.Response, error) {
return irt(req)
}
// InterceptorChain is a series of [Interceptor] functions that will be applied
// on each request. A chain should be supplied as the [http.Client.Transport]
// on a http client.
func InterceptorChain(rt http.RoundTripper, interceptors ...Interceptor) http.RoundTripper {
if rt == nil {
rt = http.DefaultTransport
}
for _, interceptor := range interceptors {
rt = interceptor(rt)
}
return rt
} |
Now, in
net/http, for server side, we haveHandler&HandlerFunc,HandlerFuncis the convenient way for user to define new handler, but in client side, we only haveRoundTripper, so I proposal to addRoundTripperFunctonet/http.With this new type, we can easily implement
RoundTripperinterface.In modern web application, middleware pattern is widely used. With
Middlewarewe can add more action before/after handler/request call.For the server side, we can define
Middlewareor similar:For the client side, we define
Interceptoror similar:All the above are not necessary, but can reduce and simplify user's boilerplate code.
Please consider this proposal.
The original code is middleware, interceptor & RoundTripperFunc
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