metz·log

Running (almost) anything on Nginx with uWSGI

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This is a sort of follow-up post to Running Trac on Nginx with Phusion Passenger.

As my hosting needs have slightly changed lately I now have no immediate need for running Ruby, Rails or Rack applications. I’m lately using more and more web applications but they are based on different technologies. The current list looks like:

From the list above, Phusion Passenger currently only supports Trac. Also it doesn’t seem to work with the Firefox Sync Server as its standard installation recommends virtualenv and Passenger always uses the system-wide Python installation unless you want to apply ugly hacks (loading another interpreter from a running Python script).

So overall Phusion Passenger did not look like a good match for my needs anymore and I started looking for something else that could handle as many technologies as possible without me needing to setup a different application server for each technology (and learning a different configuration syntax for each of them).

Enter uWSGI

It turns out that there’s already something that does handle most (if not all) of the above mentioned languages or frameworks and it’s called uWSGI. Despite its name, uWSGI supports far more than running Python-based UWSGI applications thanks to its plugin system and a truckload of plugins that are part of the standard distribution. This also includes Rack-based applications (probably includes Rails as well), PHP and even plain old CGI.

Unfortunately uWSGI is not yet available in Debian Squeeze (stable) but it’s part of Debian Wheezy (testing). Because Wheezy is currently in feature freeze and has proven to be “stable enough” on all my Linux boxes I’ve decided to use Debian Wheezy for my new root-server.

Installing uWSGI on Debian Wheezy

Installing uWSGI is just a matter of apt-get install uwsgi-core and then add any of uwsgi-plugin-foo packages to the mix. I started with uwsgi-plugin-python and uwsgi-plugin-cgi.

For some reason Debian does not package the PHP plugin for uWSGI, fortunately building it manually is not that much work:

  • Install packages libphp5-embed and php5-dev
  • Fetch uwsgi package sources using apt-get source uwsgi
  • Copy debian/buildconf/uwsgi-plugin.ini.in to debian/buildconf/uwsgi-plugin.ini and replace @@curdir@@ with the absolute path to the source directory
  • Execute python uwsgiconfig.py --plugin plugins/php debian/buildconf/uwsgi-plugin.ini to build the plugin
  • The resulting plugin_php.so can now be copied to /usr/lib/uwsgi/plugins/

Please note that every time libphp5-embed received an update so far I also had to rebuild the plugin. I don’t know exactly why that’s the case but I guess it’s a trick to make me submit a patch to the Debian uWSGI packager(s) ;)

Configuring uWSGI and Nginx

In the following I’ll show a few configuration examples how I got different applications and languages working with uWSGI and Nginx.

Because all this is on Debian Wheezy every uWSGI app creates a socket at /var/run/uwsgi/app/APPNAME/socket. For more information about the default configuration of an application just check /usr/share/uwsgi/conf/default.ini and uWSGI Configuration Options.

In my examples all uWSGI apps run as their own user instead of www-data. This is of course not needed but should be a little bit more secure. For even more separation it would probably make sense to add chrooting and setting POSIX Capabilites as documented in the Securing uWSGI section of uWSGI documentation but I’ll omit that to keep the examples small.

Cgit on Nginx with uWSGI

Getting a CGI application like cgit working is quite easy, at least if there’s only one CGI binary to execute.

/etc/uwsgi/apps-available/cgit.ini

[uwsgi]
plugins = cgi
chown-socket = www-data:www-data
uid = cgit
gid = cgit
processes = 1
threads = 8
cgi = /usr/local/lib/cgi-bin/cgit.cgi

For Nginx it’s just a matter of adding a new virtual host and pointing it to the socket created by the above configuration:

/etc/nginx/sites-available/com.example.git.conf

server {
    root /srv/www/com.example.git;
    server_name git.example.com;
    location / {
        try_files $uri @cgit;
    }
    location @cgit {
        include uwsgi_params;
        uwsgi_modifier1 9;
        uwsgi_pass unix:/var/run/uwsgi/app/cgit/socket;
    }
}

Trac on Nginx with uWSGI

Setting up Trac is very similar, except that defining the entry point of a Python-based WSGI application works a bit different:

/etc/uwsgi/apps-available/trac.ini

[uwsgi]
plugins = python
chown-socket = www-data:www-data
uid = trac
gid = trac
env = TRAC_ENV=/srv/trac/projectname
module = trac.web.main:dispatch_request

Adding a virtual host to Nginx is also only a few lines:

/etc/nginx/sites-available/com.example.trac.conf

server {
    root /srv/www/com.example.trac;
    server_name trac.example.com;
    location / {
        include uwsgi_params;
        uwsgi_pass unix:/var/run/uwsgi/app/trac/socket;
    }
}

Piwik on Nginx with uWSGI

Getting Piwik running is easy in terms of uWSGI and shows little changes except for the plugins key:

/etc/uwsgi/apps-available/trac.ini

[uwsgi]
plugins = php
chown-socket = www-data:www-data
uid = piwik
gid = piwik
cheaper = 1
processes = 4

Now the Nginx configuration is a bit more elaborate. Parts of it are based on François Lefèvre’s post about Piwik Hardening with Nginx and PHP-FPM and perusio’s piwik-nginx config example at GitHub.

/etc/nginx/sites-available/com.example.trac.conf

server {
    listen 80;
    root /srv/www/com.example.piwik;
    server_name piwik.example.com;
    index piwik.php;
    # For administrative access
    location = /index.php {
        include uwsgi_params;
        uwsgi_modifier1 14;
        uwsgi_pass unix:/var/run/uwsgi/app/piwik/socket;
        allow 127.0.0.1; # only via ssh tunnel
        deny all;
    }
    # For public access
    location = /piwik.php {
        include uwsgi_params;
        uwsgi_modifier1 14;
        uwsgi_pass unix:/var/run/uwsgi/app/piwik/socket;
    }
    # Any other attempt to access PHP files is forbidden
    location ~* ^.+\.php$ {
        return 403;
    }
    # Redirect to the root if attempting to access a txt file.
    location ~* (?:DESIGN|(?:gpl|README|LICENSE)[^.]*|LEGALNOTICE)(?:\.txt)*$ {
        return 302 /;
    }
    # Disallow access to several helper files.
    location ~* \.(?:bat|html?|git|ini|sh|svn[^.]*|txt|tpl|xml)$ {
        return 404;
    }
    # Disallow access to directories
    location ~ ^/(config|core|lang|misc|tmp)/ {
        deny all;
    }
}

Good bye Apache and mod-fcgid

uWSGI is a real breeze to configure. Combining it with Nginx gave me an IMHO pretty clean solution for separating web applications from eachother and having a single point for configuring apps regardless of what technology they use.

Especially the configuration part got me sold on uWSGI after I looked back at all the hoops I had to jump through in the past with apache fcgid/fastcgi modules, suexec, php-fpm and numerous wrapper-scripts to get fastcgi and suexec to play nicely together.

Finally I also have gained easier control over the number of spawned processes, something which wasn’t so straightforward with mod-fcgid and php5-cgi.