HTTP2

Compiling Nginx with HTTP/2 and ALPN

by Orange

To have HTTP/2 fully supported in Nginx, you will need OpenSSL 1.0.2+ to have APLN enabled (What is APLN)

Unfortunately, nowadays most linux distributions are shipping with older version of OpenSSL. For example Ubuntu 14.04 is using openssl 1.0.1f

I can also use 3rd party repositories but I couldn’t find out something I think it is trusted

So it leaves me with only one option: compiling from source

Good thing is, it is pretty easy to compile nginx with a custom OpenSSL. You don’t even have to compile the OpenSSL and install into the system (which could break your system dependences)

All you have to do are:

  1. Download the latest stable OpenSSL from https://www.openssl.org/source/ and extract the tar
  2. Download the latest stable nginx from http://nginx.org/en/download.html and extract the tar
  3. Go into nginx source folder and 
    ./configure --with-openssl=/path/to/openssl-1.0.2f --with-http_ssl_module --with-http_v2_module
make && make install
    • Note: –with-openssl points to the openssl source folder instead of the installation folder
  4. Enable HTTP/2 in nginx configure file

That’s it

And here is how you can verify if your website is now supporting HTTP/2 and ALPN

echo |  /usr/local/ssl/bin/openssl s_client -alpn h2 -connect c11e.wodemo.com:443 | grep ALPN

Which will report

  • “ALPN protocol: h2”
  • or “No ALPN negotiated”

什么是 ALPN(应用层协议协商) What is ALPN (Application-Layer Protocol Negotiation)

by Orange

在没有启用 ALPN 的时候，加载一个 HTTP/2 页面的步骤是：

Without ALPN, the steps to load a HTTP/2 page would be like:

  1. TLS 握手 (TLS handshake)
  2. 浏览器/客户端 发送带有 “Upgrade: h2c” 头的 HTTP/1.1 请求 (Browser/Client speaks HTTP/1.1 to server with “Upgrade: h2c” Header)
  3. 服务器回复 101 Switching 并将链接升级至 HTTP2 (Server responds with 101 Switching to upgrade to HTTP2)
  4. 现在服务器和客户端采用 HTTP2 协议交流 (Now they talks via HTTP2)

在启用了 ALPN 的情况下：

With ALPN, the steps would be:

  1. TLS握手，并且在握手过程中，客户端告诉服务器一个客户端支持的协议列表，然后服务器回复客户端支持 HTTP2 协议 (TLS handshake and in the handshake client tells the server the list of protocol it supports and server respond in handshake saying that it supports HTTP2 as well)
  2. 现在服务器和客户端采用 HTTP2 协议交流 (Now they talks via HTTP2)

可以看出，使用 ALPN 之后，客户端和服务器的交互少了一轮握手（不需要 Upgrade 和 101 Switching）

As you can see there is one less round trip with ALPN (No step of Upgrade and 101 Switching)

RFC: http://tools.ietf.org/html/rfc7301