HTTP/2 (HTTP/2.0) is the major upgrade over older version HTTP/1.1 protocol.HTTP/1 was released in 1997 and after a long time the HTTP/2 is released in 2015. HTTP/2 protocol is based on SPDY (generally known as speedy). Some of the key improvements of HTTP/2 are:

• Server push: Server will pro-actively sent components to clients, So clients doesn’t need to wait for sending requests to server.
• Multiplexing: Reducing number of active connection by bundling multiple HTTP requests from client and sent to server.
• Encryption: efficiently use to encryption with TLS protocol in HTTP/2 over HTTP/1.1.
• HTTP header compression: Compressed headers will reduce the overhead of additional requests to web server.

This article will help you to enable HTTP/2.0 in Apache web server on CentOS / Red Hat/ Debian and Ubuntu systems.

Install or Update Apache

HTTP/2 protocol supported over Apache version >=2.4.17. So make sure that your Apache version supporting HTTP/2 protocol. If you have not installed Apache or using older version upgrade it first. Use the following commands to add PPA for installing latest Apache2 version on your Ubuntu system.

$ sudo apt-get install python-software-properties
$ sudo add-apt-repository ppa:ondrej/apache2
$ sudo apt-get update
$ sudo apt-get install apache2

Verify Apache Version

After successful installation of Apache2 web server on your system, make sure you have Apache >=2.4.17, Earlier version does not supports HTTP/2 protocol.

$ apache2 -v

Server version: Apache/2.4.17 (Ubuntu)
Server built:   2015-11-05T00:00:00

Enable HTTP/2 in Apache

HTTP/2 protocol requires SSL/TLS virtual hosts. You can’t use HTTP/2 protocol without SSL/TLS enabled websites. Now edit your website VirtualHost and add http2 keyword in listen section.

$ sudo a2enmod http2
$ sudo service apache2 restart

Verify HTTP/2

Now configure a VirtualHost with SSL for your domain and use following online tool for testing HTTP/2 support on your website.

https://tools.keycdn.com/http2-test