Example function to proxy a PDF from one URL to a http handler func

main.go

package main

import (
	"fmt"
	"io"
	"net"
	"net/http"
	"time"
)

func main() {
	pdfLocation := "http://www.bcregistryservices.gov.bc.ca/local/bcreg/documents/forms/reg50a.pdf"
	fileName := fmt.Sprintf("%s_%s-%d.pdf", "Alice", "Smith", time.Now().Unix())
	http.HandleFunc("/", getFileProxyHandler(pdfLocation, fileName))

	fmt.Println("Listening on port 8080")
	err := http.ListenAndServe(":8080", nil)
	if err != nil {
		// TODO(jon) handle error
		panic(err)
	}
}

func getFileProxyHandler(url, fileName string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		// this might have to change depending on api2pdf delays
		timeout := time.Duration(30) * time.Second
		transport := &http.Transport{
			ResponseHeaderTimeout: timeout,
			Dial: func(network, addr string) (net.Conn, error) {
				return net.DialTimeout(network, addr, timeout)
			},
			DisableKeepAlives: true,
		}
		client := &http.Client{
			Transport: transport,
		}
		resp, err := client.Get(url)
		if err != nil {
			// TODO(jon) handle error
			panic(err)
		}
		defer resp.Body.Close()

		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s", fileName))
		w.Header().Set("Content-Type", resp.Header.Get("Content-Type"))
		w.Header().Set("Content-Length", resp.Header.Get("Content-Length"))

		_, err = io.Copy(w, resp.Body)
		if err != nil && err != io.EOF {
			// TODO(jon) handle error
			panic(err)
		}
	}
}