Go: `NewSingleHostReverseProxy`

HTTPS proxy:

main.go

package main

import (
    "log"
    "net/http"
    "net/http/httputil"
    "net/url"
)

func main() {
    target, err := url.Parse("https://rs.aspsp.ob.forgerock.financial:443")
    log.Printf("forwarding to -> %s%s\n", target.Scheme, target.Host)

    if err != nil {
        log.Fatal(err)
    }
    proxy := httputil.NewSingleHostReverseProxy(target)

    http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
        // https://stackoverflow.com/questions/38016477/reverse-proxy-does-not-work
        // https://forum.golangbridge.org/t/explain-how-reverse-proxy-work/6492/7
        // https://stackoverflow.com/questions/34745654/golang-reverseproxy-with-apache2-sni-hostname-error

        // log.Println("req.Host=", req.Host)
        // log.Println("req.URL.Host=", req.URL.Host)
        req.Host = req.URL.Host

        proxy.ServeHTTP(w, req)
    })

    err = http.ListenAndServe(":8989", nil)
    if err != nil {
        panic(err)
    }
}

build and run

$ go run main.go &
2018/10/23 19:53:12 forwarding to -> httpsrs.aspsp.ob.forgerock.financial:443
$ curl http://localhost:8989/open-banking/v2.0/accounts
{"Code":"OBRI.FR.Request.Invalid","Id":"c37baec213dd1227","Message":"An error happened when parsing the request arguments","Errors":[{"ErrorCode":"UK.OBIE.Header.Missing","Message":"Missing request header 'x-fapi-financial-id' for method parameter of type String","Url":"https://docs.ob.forgerock.financial/errors#UK.OBIE.Header.Missing"}]}%