Nginx configuration for Piwik

Introduction

This is a nginx configuration for running Piwik. It assumes that the domain assigned to Piwik is stats.example.com.

Change this according to your server setup.

Features

Filtering of invalid HTTP Host headers.
Filtering of referrer when serving the Piwik JS or any other static files.
Hiding of all text files.
Restricted handling of PHP files. Only index.php and piwik.php are allowed. All other attempts to run a PHP file return a 404.
IPv6 and IPv4 support.
Possibility of using Apache as a backend for dealing with PHP. This means using Nginx as a reverse proxy.
Static files use the OS buffer cache.
Caching of most Piwik pages with exceptions for the installation and administrative tasks.
piwik.php is cached with a long TTL (2h). Hence faster to register an access.
Inline robots.txt that disables all crawling.

Nginx as a Reverse Proxy: Proxying to Apache for PHP

This applies if you absolutely need to use the rather bad habit of deploying web apps relying on .htaccess, or you just want to use Nginx as a reverse proxy. The config allows you to do so. Note that this provides some benefits over using only Apache, since Nginx is much faster than Apache. Furthermore you can use the proxy cache and/or use Nginx as a load balancer.

IPv6 and IPv4

The configuration of the example vhosts uses separate sockets for IPv6 and IPv4. This way is simpler for those not (yet) having IPv6 support to disable it by commenting out the listen directive with the ipv6only=on parameter.

Note that the IPv6 address uses an IP stolen from the IPv6 Wikipedia page. You must replace the indicated address by your address.

Installation

Move the old /etc/nginx directory to /etc/nginx.old.
Clone the git repository from github:

git clone https://github.com/perusio/piwik-nginx.git /etc/nginx
Edit the sites-available/stats.example.com.conf configuration file to suit your needs. Especially replace stats.example.com with your domain.
Setup the PHP handling method. It can be:

Upstream HTTP server like Apache with mod_php. To use this method comment out the include upstream_phpcgi.conf; line in nginx.conf and uncomment the lines:
```
 include reverse_proxy.conf;
 include upstream_phpapache.conf;
```
Now you must set the proper address and port for your backend(s) in the upstream_phpapache.conf. By default it assumes the loopback 127.0.0.1 interface on port 8080. Adjust accordingly to reflect your setup.

Comment out all fastcgi_pass directives in stats.example.com.conf Uncomment out all the proxy_pass directives. They have a comment around them, stating these instructions.
FastCGI process using php-cgi. In this case an init script is required.
PHP FPM, this requires you to configure your fpm setup, in Debian/Ubuntu this is done in the /etc/php5/fpm directory. This is how the server is configured out of the box. It uses UNIX sockets. You can use TCP sockets if you prefer.

Look here for an example configuration of php-fpm.

Check that the socket is properly created and is listening. This can be done with netstat, like this for UNIX sockets:
```
netstat --unix -l
```
or like this for TCP sockets:
```
netstat -t -l
```
It should display the PHP CGI socket.

Note that the default socket type is UNIX and the config assumes it to be listening on unix:/tmp/php-cgi/php-cgi.socket, if using the php-cgi, or in unix:/var/run/php-fpm.sock using php-fpm and that you should change to reflect your setup by editing upstream_phpcgi.conf.

Setup the cache for piwik.php. It depends if you use either FastCGI or Apache for processing PHP.

FastCGI: Create the /var/cache/nginx/fcgicache directory if you're serving PHP with php-fpm or php cgi. This directory must be owned by the unpriveleged nginx user. In debian it's www-data.
Apache: Create the /var/cache/nginx/proxycache directory if you're serving PHP with Apache. This directory must be owned by the unpriveleged nginx user. In debian it's www-data. Comment out all the lines where fcgi_cache is referenced. You must uncomment the line include proxy_cache_zone.conf; on nginx.conf.

Create the /etc/nginx/sites-enabled directory and enable the virtual host using one of the methods described below.

Note that if you're using the nginx_ensite script described below it creates the /etc/nginx/sites-enabled directory if it doesn't exist the first time you run it for enabling a site.
Reload Nginx:

/etc/init.d/nginx reload
Check that your site is working using your browser.
Remove the /etc/nginx.old directory.
Done.

Caching status

You can check if the responses are being cached or not. For the short term cache check for a X-Piwik-Cache header with a HIT/EXPIRED/MISS/UPDATING/STALE value. The same applies to the long cache: check for a X-Piwik-Long-Cache header with a HIT/EXPIRED/MISS/UPDATING/STALE value.

Example:

   curl -I stats.example.com/piwik.php
   HTTP/1.1 200 OK
   Server: nginx
   Date: Mon, 02 Jan 2012 13:17:15 GMT
   Content-Type: text/html
   Connection: keep-alive
   Keep-Alive: timeout=10
   Vary: Accept-Encoding
   Expires: Thu, 01 Jan 1970 00:00:01 GMT
   Cache-Control: no-cache
   X-Piwik-Long-Cache: MISS

Acessing the php-fpm status and ping pages

You can get the status and ping pages for the running instance of php-fpm. There is a php_fpm_status.conf file with the configuration for both features.

the status page at /fpm-status;
the ping page at /ping.

For obvious reasons access to these pages is restricted to a given set of IP addresses. In the suggested configuration only from localhost and non-routable IPs of the 192.168.1.0 network.

The allowed hosts are defined in a geo block in file php_fpm_status_allowed_hosts.conf. You should edit the predefined IP addresses to suit your setup.

To enable the status and ping pages uncomment the line in the stats.example.com.conf virtual host configuration file.

Valid referrers and resource usage constraining

Note that this configuration assumes that you are stating exactly which hosts can use your Piwik installation. In the example config, for all static files, i.e., images, Javascript, Flash and CSS there is a valid_referers block where all allowed hosts are enumerated. You should replace the *.mysite.com and othersite.com with the hosts where you want Piwik to be used for analytics.

If that is too much of an hassle for you, then just comment out the valid_referers block.

If you are using this configuration and you are not getting any results for a particular site where you have Piwik enabled, then first check for the valid_referers block. To see if that host is enumerated there.

Blacklisting User Agents and Referers

There are some serious issues with some User Agents out there. Some are operated in a bandwidth hogging fashion. Implementing bots that use and abuse the site is bandwidth. Even more serious is when the User Agent is used for exploits. Trying to penetrate/crack the site through crafted scripts running under the cloak of a well meaning bot.

The same applies to Referers where shady sites sent traffic to you that only hijacks the bandwith and curtail the correct usage of Piwik.

There is a blacklist of User Agents and Referers that is disabled by default. You have to enable it explicitly.

Uncomment the include blacklist.conf line in the nginx.conf configuration file to enable User Agent and Referer blacklisting. Of course you can define your own list of blacklisted User Agents.

Getting the latest Nginx packaged for Debian or Ubuntu

There's a Debian repository with the latest version of Nginx. This is packaged for Debian unstable or testing. The instructions for using the repository are presented on this page.

It may work on Ubuntu. Since Ubuntu seems to appreciate more finding semi-witty names for their releases instead of making clear what is the status of the software included. Is it stable? Is it testing? Is it unstable? The package may work with your currently installed environment or not. I don't have the faintest idea which release to advise. So you are on your own. Generally the APT machinery will sort out for you any dependencies issues that might exist.

Other Nginx configs on github

Securing your PHP configuration

There's a small shell script that parses your php.ini and sets a sane environment, be it for development or production settings.

Grab it here.

Keeping PHP always running

php-fpm is hardly perfect, or better said, it happens quite often that PHP has extremely long running processes that can completely clog PHP processing. To obviate that I've created a shell script that relaunches php-fpm whenever PHP hangs.