How to do a https request with proxy

I am able to do a http or https client request without setting up a proxy,

enter code here
tr := &http.Transport{
	TLSClientConfig: &tls.Config{InsecureSkipVerify: true},		
}

client := &http.Client{}
client.Transport = tr

request, err := http.NewRequest("HEAD", "http://www.???.com", nil)
request.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36")

resp, err := client.Do(request)

if err != nil {
	log.Fatalln(err)
	return
}
defer resp.Body.Close()

httpcode = resp.Status

This script is working ok, I get a 200 ok when I request https url, but if I set up proxy , the script:

proxyString := "https://47.91.179.xxx:443"
proxyUrl, _ := url.Parse(proxyString)

tr := &http.Transport{
    Proxy: http.ProxyURL(proxyUrl),
	TLSClientConfig: &tls.Config{InsecureSkipVerify: true},	
    
}

client := &http.Client{}
client.Transport = tr

....................

I always get "Bad request", I read docs: https://golang.org/pkg/net/http/:

...........
Starting with Go 1.6, the http package has transparent support for the HTTP/2 protocol when using HTTPS. Programs that must disable HTTP/2 can do so by setting Transport.TLSNextProto (for clients) or Server.TLSNextProto (for servers) to a non-nil, empty map. Alternatively, the following GODEBUG environment variables are currently supported:
..............

So, I tried to stop http2:

tr := &http.Transport{
	Proxy: http.ProxyURL(proxyUrl),
	//Proxy: http.ProxyFromEnvironment,
	TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
	TLSNextProto:    make(map[string]func(authority string, c *tls.Conn) http.RoundTripper),
}

same problem, "Bad request". I tried os.Setenv("HTTPS_PROXY", "47.91.???.???:443"), It is the same result.
This is logged in server:

{S;}220.255.95.68{S;}-{S;}07/Mar/2017:17:01:47 +0800{S;}CONNECT www.panpacific.com:443 HTTP/1.1{S;}400{S;}173{S;}340{S;}-{S;}-{S;}-{S;}-{S;}-{S;}www.panpacific.com

So, Does golang support https client request via proxy? How do I get correct results?

There doesn't appear to be anything wrong with your Client.Transport.Proxy configuration. Both attempted approaches (ProxyURL and ProxyFromEnvironment) should work fine to specify a forward proxy.

Relevant question: https://stackoverflow.com/q/51845690/86967

Something to look out for, however unlikely, is that subsequent client-side calls to not somehow bypass the use of WriteProxy and instead call Write directly -- since this would defeat the proxy specification.

Given the information provided here, "Bad Request" likely indicates that you are reaching the proxy, but that it is not working correctly as a generic HTTP/HTTPS forward proxy, which is what Client.Transport.Proxy would specify.

Maybe some clarity would be added here: How to use Nginx as a HTTP/HTTPS proxy server?. In summary, NGINX is not normally used as a forward proxy, so maybe this isn't what you are trying to do.

If you are trying to use NGINX as a reverse proxy, then configuration is a server-side concern and your clients do not need special proxy configuration -- just change your request URL to point to the proxy.

Side note: If not otherwise specified, &http.Client{} will use DefaultTransport which automatically includes ProxyFromEnvironment, so the extra proxy configuration is only required if you are constructing a non-default Transport (as is done in the question in order to specify InsecureSkipVerify) or you want to have an application-specific proxy confuration. And, to repeat, client-side proxy configuration is only needed when using a forward proxy.