Install nginx with http2 support on Ubuntu

Backup your nginx.conf files (usually under /etc/nginx/sites-available)
Remove old nginx - nginx incl. nginx-common: apt-get autoremove --purge nginx nginx-common
Add sources list for new nginx

Create /etc/apt/sources.list.d/nginx.list with the following content:

deb http://nginx.org/packages/mainline/ubuntu/ trusty nginx
deb-src http://nginx.org/packages/mainline/ubuntu/ trusty nginx

add nginx signing key:wget -q -O- http://nginx.org/keys/nginx_signing.key | sudo apt-key add -
update package cache: sudo apt-get update
install new nginx: sudo apt-get install nginx
fix /etc/nginx/nginx.conf
- add this to the end of the http section:
  - Set user to www-data
  - Set worker_processes to 4
  - Set tcp_nopush to on
  - Set tcp_nodelay to on
  - Set types_hash_max_size to 2048
  - Set server_tokens to off
  - Set gzip to on
  - Set gzip_disable to "msie6"
  - Add include /etc/nginx/sites-enabled/*;
- remove /etc/nginx/conf.d/default.conf
- or, sudo rm -rf /etc/nginx/conf.d/default.conf
fix /etc/nginx/fastcgi_params:
- add fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
- add sites-* folders:sudo mkdir /etc/nginx/sites-available /etc/nginx/sites-enabled
- add your previously backuped site configs and enable them by symlinking in /etc/nginx/sites-enabled.

Enable http2

Add to your https hosts congig:

  listen 443 http2;
  listen [::]:443 http2;

sudo systemctl stop nginx
sudo systemctl start nginx