Day 20 - A go http/2 server example

I was really excited when i read that support for http2 is now on golang.org! I was thinking about checking out SPDY in go for a long time, but now HTTP/2 support moved one important step further.

I think its one of the "Next big Things" on the interweb (the last change to http was 18! years ago)

So i skip SPDY and go directly for HTTP/2 - this post is about how to get a first grip and test it serverside as a go html server example.

Test preparations clientside:

1. Get a browser that has http/2 support enabled by default: Chrome Canary
2. Download the http2 and spdy indicator addon for chrome 
3. Test your browsers http2 support at: https://http2.akamai.com/demo

 Serverside::

1. Cd into your GOPATH/src
2. Run go get golang.org/x/net/http2
3. Check if the package has been downloaded

Create, build and run:

1. Create a new go project, name it eg. testHttp2Server
2. Create a ssl certificate (localhost.cert and localhost.key)
   You can ether generate a self signed cert: selfsignedcertificate
   or use mine: testHttp2Server
   This two files must be in the same directory as the server binary.
3. Code for http2Server.go:
   
   
   package main

   import (

       "fmt"

       "golang.org/x/net/http2"

       "html"

       "log"

       "net/http"

   )

   func main() {

       var srv http.Server

       http2.VerboseLogs = true

       srv.Addr = ":8080"

       // This enables http2 support

       http2.ConfigureServer(&srv, nil)

       // Plain text test handler

       // Open https://localhost:8080/randomtest

       // in your Chrome Canary browser

       http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {

           fmt.Fprintf(w, "Hi tester %q\n", html.EscapeString(r.URL.Path))

           ShowRequestInfoHandler(w, r)

       })

       // Listen as https ssl server

       // NOTE: WITHOUT SSL IT WONT WORK!!

       // To self generate a test ssl cert/key you could go to

       // http://www.selfsignedcertificate.com/

       // or read the openssl manual

       log.Fatal(srv.ListenAndServeTLS("localhost.cert", "localhost.key"))

   }

   func ShowRequestInfoHandler(w http.ResponseWriter, r *http.Request) {

       w.Header().Set("Content-Type", "text/plain")

       fmt.Fprintf(w, "Method: %s\n", r.Method)

       fmt.Fprintf(w, "Protocol: %s\n", r.Proto)

       fmt.Fprintf(w, "Host: %s\n", r.Host)

       fmt.Fprintf(w, "RemoteAddr: %s\n", r.RemoteAddr)

       fmt.Fprintf(w, "RequestURI: %q\n", r.RequestURI)

       fmt.Fprintf(w, "URL: %#v\n", r.URL)

       fmt.Fprintf(w, "Body.ContentLength: %d (-1 means unknown)\n", r.ContentLength)

       fmt.Fprintf(w, "Close: %v (relevant for HTTP/1 only)\n", r.Close)

       fmt.Fprintf(w, "TLS: %#v\n", r.TLS)

       fmt.Fprintf(w, "\nHeaders:\n")

       r.Header.Write(w)

   }

   
   

4. Compile:  go build http2Server.go
5. Run the http2Server binary

Test it:

1. Open in Chrome Canary: https://localhost:8080/kim
2. Accept the certificate security error, continue to localhost
3. Check if Protocol is HTTP/2.0, example output should be like:
   
   

   Hello tester "/kim"
   Method: GET
   Protocol: HTTP/2.0
   Host: localhost:8080

   ... 

NOTE: http/2 in go ONLY WORKS WITH SSL/TLS! (currently)
I not sure why, but i did not got the server to support http/2 without TLS!
This could be a clientside or serverside issue - i dont know currently.

Some discussions about this:
why-wouldnt-it-be-great-if-http-2-would-only-allow-communication-via-tls
daniel.haxx.se tls-in-http2
arstechnica http2-finished-coming-to-browsers-within-weeks

As far as i have understood it, the spec says it "should be" possible to use it without the need to buy SSL certificates:
https://http2.github.io/http2-spec/
rfc7540 - html2