Mounting a disk image with Windows tools only

Coming from the *NIX/Mac world I frequently find myself mounting ISO images as local disks for software installation, etc.

The same requirement recently came up for me on a Windows platform and I was a little stumped as I did not want to spend any money on this (as I see this as an intrinsic part of the the OS) by buying Alcohol or Daemon Tools.

To my surprise Microsoft actually has a (unsupported) tool (Virtual CD-ROM Control Panel) and driver that provides virtual CD-ROM services.

Unfortunately the solution is XP-only. Download the executable above and install the service. Its readme is quite short and to the point so getting this going is pretty easy.

Have fun!

Auto-sizing jQuery-UI Dialog

I recently upgraded all my jquery and jquery-ui (and some supporting) libs. Part of this upgrade was also to get the latest version of nyroModal working.

After several hours of chasing issues with the lib I decided to rip it out of my app and rather use the jquery-ui dialog plugin that ships with the native lib.

A large bugbear with nyroModal has always been that I could never get the dialogs to flow around the different content lengths that I was populating them with properly. After retrofitting the jquery-ui dialog plugin I ran into the similar issues I had with nyroModal.

Whenever the content of my dialog was greater than the distance from the top of the dialog window to the bottom of the viewport, the dialog would simply disappear off the viewport (regardless of whether it had a scrollbar or not).

What I wanted was for the dialog to automagically adjust its vertical height based on the size of the content it contains relative to the top of the dialog position and the bottom of the viewport.

The fact that I am using FBBorderLayout (yep, I am aware this project has been superseded by the jQuery UI plugin but I am taking baby steps here) to set up a nice layout that stops the page from scrolling down and contributes to the dialog sizing off the viewport.

The scene
Based on the documentation on the jquery-ui dialog plugin page I created something like this.

As you can see from this page the dialog stretched off the screen with no scrollbar or way to scroll down to see the content of the dialog.

Styling
Ok, not quite what we wanted so I added the following style code to the head to try and get the dialog container to automatically flow and add a scrollbar if the content was too big.

And? It had no effect whatsoever. I tried all possible styling that I could find to try and get the dialog container to play nice but to no avail.

Unlikely rescuer
I scoured the web for a possible solution. All I found were a lot of questions about this phenomenon but no real usable solutions or suggestions (beyond the styling I'd already tried).

I then thought of trying to calculate the height programatically and set the height of the dialog contents prior to displaying it.

You'll notice I stopped the dialog from displaying automatically by adding the 'autoOpen: false' option to the dialog initialization. This is required so that I am able to calculate the height before displaying the dialog.

Finally
Here's the complete source file for posterity.

Enjoy!

Installing the MySQL gem on OS X

If you manage your system packages via the MacPorts system you may run into some problems when trying to install the native MySQL driver gem on OS X.

Typically, you'd see output like this when trying to install the gem:

$ sudo gem install mysql
Building native extensions.  This could take a while...
ERROR:  Error installing mysql:
        ERROR: Failed to build gem native extension.

/opt/local/bin/ruby extconf.rb
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lm... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lz... yes
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lsocket... no
checking for mysql_query() in -lmysqlclient... no
checking for main() in -lnsl... no
checking for mysql_query() in -lmysqlclient... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers.  Check the mkmf.log file for more
details.  You may need configuration options.

Provided configuration options:
        --with-opt-dir
        --without-opt-dir
        --with-opt-include
        --without-opt-include=${opt-dir}/include
        --with-opt-lib
        --without-opt-lib=${opt-dir}/lib
        --with-make-prog
        --without-make-prog
        --srcdir=.
        --curdir
        --ruby=/opt/local/bin/ruby
        --with-mysql-config
        --without-mysql-config
        --with-mysql-dir
        --without-mysql-dir
        --with-mysql-include
        --without-mysql-include=${mysql-dir}/include
        --with-mysql-lib
        --without-mysql-lib=${mysql-dir}/lib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-mlib
        --without-mlib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-zlib
        --without-zlib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-socketlib
        --without-socketlib
        --with-mysqlclientlib
        --without-mysqlclientlib
        --with-nsllib
        --without-nsllib
        --with-mysqlclientlib
        --without-mysqlclientlib


Gem files will remain installed in /opt/local/lib/ruby/gems/1.8/gems/mysql-2.7 for inspection.
Results logged to /opt/local/lib/ruby/gems/1.8/gems/mysql-2.7/gem_make.out

Based on those errors the configure process seems to be failing when looking for MySQL libs. The default path to the libs based on extconf.rb seems to be /usr/local which is not where the ports system installs MySQL.

All you need to do is point to the correct mysql_config and let the gem install command line know of this to get things going:

$ sudo gem install mysql -- --with-mysql-config=/opt/local/bin/mysql_config5  
Building native extensions.  This could take a while...
Successfully installed mysql-2.7
1 gem installed

All's well that ends well.

nginx/passenger: Exception RangeError in PhusionPassenger::Railz::ApplicationSpawner (bignum too big to convert into `long')

Nasty.

I am running nginx+passenger on my OS X laptop and after getting the passenger module installed I got the following stacktrace in /opt/local/var/log/nginx/error.log:

*** Exception RangeError in PhusionPassenger::Railz::ApplicationSpawner (bignum too big to convert into `long') (process
 56051):
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/utils.rb:363:in `setgid'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/utils.rb:363:in `switch_to_user'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/utils.rb:328:in `lower_privilege'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/railz/application_spawner.rb:250:in
 `initialize_server'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/utils.rb:230:in `report_app_init_st
atus'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/railz/application_spawner.rb:237:in
 `initialize_server'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server.rb:193:in `start_sy
nchronously'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server.rb:162:in `start'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/railz/application_spawner.rb:213:in
 `start'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/spawn_manager.rb:261:in `spawn_rail
s_application'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server_collection.rb:126:i
n `lookup_or_add'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/spawn_manager.rb:255:in `spawn_rail
s_application'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server_collection.rb:80:in
 `synchronize'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server_collection.rb:79:in
 `synchronize'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/spawn_manager.rb:254:in `spawn_rail
s_application'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/spawn_manager.rb:153:in `spawn_appl
ication'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/spawn_manager.rb:286:in `handle_spa
wn_application'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server.rb:351:in `__send__
'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server.rb:351:in `main_loo
p'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/lib/phusion_passenger/abstract_server.rb:195:in `start_sy
nchronously'
        from /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/bin/passenger-spawn-server:61

So, what's up?

The old switcheroo
Passenger implements User Switching which works around the age old problem that plagues most other scripting languages where they run in the same context as the web server they are accessed through.

The default behaviour is for rails apps to be started as the owner of config/environment.rb. There are however some points that should be noted:

• The owner of environment.rb must have read access to the rails application folder, and read/write access to the rails application logs folder.


• This feature is only available if nginx is started by root. This is the case on most nginx installations.


• Under no circumstances will applications be run as root. If environment.rb is owned as root or by an unknown user, then the rails application will run as the user specified by passenger_default_user.

In my case the project was owned by root so changing that to a local user fixed the problem.

Home made nginx + phusion passenger OS X port

The instructions to do this are similar to those in my previous article.

Install passenger gem
The first step is to install the Phusion Passenger gem:

$ sudo gem install -V -r passenger
[...]
Installing RDoc documentation for passenger-2.2.4...

Take note of where the passenger gem installed the nginx module code (ext/nginx/*) that will be required further down. In this case the install directory will be /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/ext/.

Compile nginx passenger module
You also need to compile the passenger nginx module if it was not already compiled:

$ cd /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/ext/
$ sudo rake nginx
[...]
g++ ext/nginx/HelperServer.cpp -o ext/nginx/HelperServer -Iext -Iext/common -D_REENTRANT -I/usr/local/include -Wall -g -DPASSENGER_DEBUG -DBOOST_DISABLE_ASSERTS  ext/nginx/libpassenger_common.a ext/nginx/libboost_oxt.a -lpthread

Modify the nginx Portfile
Ensure you have nginx port installed. Your Portfile will most likely be in /opt/local/var/macports/sources/rsync.macports.org/release/ports/www/nginx/Portfile.

Add the following variant block to the end of the file:

variant passenger description {Enable Phusion Passenger (mod_rails) support} {
    configure.args-append   --add-module=/opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4/ext/nginx
}

Rebuild/install nginx
When you try and reinstall nginx now it will use the updated Portfile and add the passenger module to the mix:

$ sudo port uninstall nginx && sudo port clean nginx
$ sudo port -vvvvv install nginx +passenger

Nginx passenger configuration
To enable and take advantage of the passenger nginx module you need to edit the /opt/local/etc/nginx/nginx.conf config. Here's an example:

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
  include       mime.types;
  default_type  application/octet-stream;

  #log_format  main  '$remote_addr - $remote_user [$time_local] $request '
  #                  '"$status" $body_bytes_sent "$http_referer" '
  #                  '"$http_user_agent" "$http_x_forwarded_for"';

  #access_log  logs/access.log  main;

  sendfile        on;
  #tcp_nopush     on;

  #keepalive_timeout  0;
  keepalive_timeout  65;

  gzip  on;

  # Enable Phusion Passenger nginx module
  passenger_root /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4;
  passenger_ruby /opt/local/bin/ruby;

  server {
    listen 80;
    server_name foo.example.com;
    root /var/www/foo/public;   # <--- be sure to point to 'public'!
    passenger_enabled on;
  }
}

Ensure that the port, server_name and root variables have valid values for your environment.

If you want to use a non-production rails environment you can add the following to the block after passenger_enabled:

      rails_env development;

Once done you can restart nginx and you should see the following processes that confirm things are running:

$ ps axw | egrep "nginx|passenger"
55935   ??  Ss     0:00.00 nginx: master process nginx
55936   ??  S      0:00.00 nginx: worker process
55925 s001  S      0:00.01 PassengerNginxHelperServer /opt/local/lib/ruby/gems/1.8/gems/passenger-2.2.4 /opt/local/bin/ruby 3 4 0 6 0 300 1 nobody 4294967294 4294967294 /tmp/passenger.55923
55938 s001  R+     0:00.00 egrep nginx|passenger

The final test to see if everything is working is to open a browser and to browse to the server_name and port defined above. Errors will be reported in /opt/local/var/log/nginx/error.log as well as the development/production logs of the rails project you're running.

Home made nginx + phusion passenger Debian/Ubuntu dep

If you are using Ubuntu Hardy then you could try using Brightbox's repo instead of building your own deb.

If you are however running some other distro then the following (non-definitive) instructions are for you.

Warning: it may be safer to install nginx + passenger via the passenger-install-nginx-module script as it will match passenger with a tested version of nginx.

The instructions below simply add passenger support to the latest nginx deb in your distro of choice.

Install passenger gem
The first step is to install the Phusion Passenger gem:

$ sudo gem install -V -r passenger
[...]
Installing RDoc documentation for passenger-2.2.4...

Take note of where the passenger gem installed the nginx module code that will be required further down:

$ gem contents passenger | egrep '/ext/nginx/' | head -n 1
/var/lib/gems/1.8/gems/passenger-2.2.4/ext/nginx/Configuration.c

In this case the install directory will be /var/lib/gems/1.8/gems/passenger-2.2.4/ext/nginx.

Compile nginx passenger module
You also need to compile the passenger nginx module if it was not already compiled:

$ cd /var/lib/gems/1.8/gems/passenger-2.2.4/ext/nginx
$ sudo rake nginx

(in /var/lib/gems/1.8/gems/passenger-2.2.4)
mkdir -p ext/nginx/libboost_oxt/boost
g++ -Iext  -D_REENTRANT -I/usr/local/include -Wall -g -DPASSENGER_DEBUG -DBOOST_DISABLE_ASSERTS -o ext/nginx/libboost_oxt/boost/exceptions.o -c ext/boost/src/pthread/exceptions.cpp
[...]
g++ ext/nginx/HelperServer.cpp -o ext/nginx/HelperServer -Iext -Iext/common -D_REENTRANT -I/usr/local/include -Wall -g -DPASSENGER_DEBUG -DBOOST_DISABLE_ASSERTS  ext/nginx/libpassenger_common.a ext/nginx/libboost_oxt.a -lpthread

Install build packages

$ sudo aptitude install fakeroot debhelper dpkg-dev autotools-dev libpcre3-dev libssl-dev

Modify APT sources.list
Open /etc/apt/sources.list and ensure you add deb-src lines for each of the universe repos. The easiest way to do this is to simply copy the universe repo lines that exist and change the starting deb to deb-src:

deb http://au.archive.ubuntu.com/ubuntu/ jaunty universe
deb-src http://au.archive.ubuntu.com/ubuntu/ jaunty universe
deb http://au.archive.ubuntu.com/ubuntu/ jaunty-updates universe
deb-src http://au.archive.ubuntu.com/ubuntu/ jaunty-updates universe

Replace 'au.archive.ubuntu.com' with the repo closest to you and also replace 'jaunty' with your distro. Ensure you do a 'sudo aptitude update' to load the latest package indexes.

Set up a packaging environment

$ mkdir -p /var/tmp/nginx-passenger && cd /var/tmp/nginx-passenger
$ apt-get source nginx
Reading package lists... Done
Building dependency tree      
Reading state information... Done
NOTICE: 'nginx' packaging is maintained in the 'Svn' version control system at:
svn://svn.debian.org/svn/collab-maint/deb-maint/nginx/trunk
Need to get 537kB of source archives.
Get:1 http://au.archive.ubuntu.com jaunty/universe nginx 0.6.35-0ubuntu1 (dsc) [1305B]
Get:2 http://au.archive.ubuntu.com jaunty/universe nginx 0.6.35-0ubuntu1 (tar) [525kB]
Get:3 http://au.archive.ubuntu.com jaunty/universe nginx 0.6.35-0ubuntu1 (diff) [11.0kB]
Fetched 537kB in 0s (1504kB/s)
gpg: Signature made Sat 21 Feb 2009 07:02:34 AM EST using DSA key ID 3FE63E00
gpg: Can't check signature: public key not found
dpkg-source: extracting nginx in nginx-0.6.35
dpkg-source: info: unpacking nginx_0.6.35.orig.tar.gz
dpkg-source: info: applying nginx_0.6.35-0ubuntu1.diff.gz
$ ls -la
total 548
drwxr-xr-x 3 root root   4096 2009-06-29 08:55 .
drwxrwxrwt 3 root root   4096 2009-06-29 08:39 ..
drwxr-xr-x 8 root root   4096 2009-06-29 08:55 nginx-0.6.35
-rw-r--r-- 1 root root  11018 2009-02-21 08:04 nginx_0.6.35-0ubuntu1.diff.gz
-rw-r--r-- 1 root root   1305 2009-02-21 08:04 nginx_0.6.35-0ubuntu1.dsc
-rw-r--r-- 1 root root 524987 2009-02-21 08:04 nginx_0.6.35.orig.tar.gz
$ rm -f nginx_*
$ mv nginx-0.6.35 nginx-passenger-0.6.35

Package customizations
In order to build our nginx-passenger custom package we need to modify the following packaging resources:

1. control file


2. changelog file


3. rules file


4. nginx.install file


5. nginx.logrotate file


6. passenger.conf file


7. postinst file

Control file

$ cd nginx-passenger-0.6.35/debian

Edit the control file and change the Source, Maintainer, Uploaders, Package, Provides, Conflicts and Description fields:

Source: nginx-passenger
Maintainer: Charl Matthee
Uploaders: Charl Matthee
Package: nginx-passenger
Provides: httpd, nginx
Conflicts: nginx
Description: small, but very powerful and efficient web server
 Nginx (engine x) is a web server created by Igor Sysoev and kindly provided
 to the open-source community. This server can be used as standalone HTTP
 server and as a reverse proxy server before some Apache or another big
 server to reduce load to backend servers by many concurrent HTTP-sessions.
 .
 This is a custom nginx package that includes Phusion Passenger
 support for nginx.

Note: spacing in the control file is significant.

More information on the control file internals can be found here.

Changelog
Add a new changelog entry in the changelog file:

nginx-passenger (0.6.35-0custom1) jaunty; urgency=low

  * New custom Passenger Phusion nginx module addition

 -- Charl Matthee   Mon, 29 Jun 2009 09:08:36 +0100

nginx (0.6.35-0ubuntu1) jaunty; urgency=low

  * New upstream bugfix release

 -- Daniel Hahler   Fri, 20 Feb 2009 21:01:23 +0100
[...]

More information on the changelog file internals can be found here.

Rules
Add the passenger module inclusion to the configure script options when nginx is built by modifying the './configure $(CONFIGURE_OPTS)' block in the rules file like this:

        ./configure $(CONFIGURE_OPTS) --conf-path=/etc/nginx/nginx.conf \
        --error-log-path=/var/log/nginx/error.log --pid-path=/var/run/nginx.pid \
        --lock-path=/var/lock/nginx.lock   --http-log-path=/var/log/nginx/access.log \
        --http-client-body-temp-path=/var/lib/nginx/body --http-proxy-temp-path=/var/lib/nginx/proxy \
        --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --with-http_stub_status_module \
        --with-http_flv_module --with-http_ssl_module --with-http_dav_module \
        --with-http_realip_module --add-module=PASSENGER_LIB_DIR

Where PASSENGER_LIB_DIR is the path you noted above when you installed the passenger gem. So, the updated block looks like this:

        ./configure $(CONFIGURE_OPTS) --conf-path=/etc/nginx/nginx.conf \
        --error-log-path=/var/log/nginx/error.log --pid-path=/var/run/nginx.pid \
        --lock-path=/var/lock/nginx.lock   --http-log-path=/var/log/nginx/access.log \
        --http-client-body-temp-path=/var/lib/nginx/body --http-proxy-temp-path=/var/lib/nginx/proxy \
        --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --with-http_stub_status_module \
        --with-http_flv_module --with-http_ssl_module --with-http_dav_module \
        --with-http_realip_module --add-module=/var/lib/gems/1.8/gems/passenger-2.2.4/ext/nginx/

More infomration on the changelog file internals can be found here.

nginx.install
Move this file to the correct name based on the package name and add the installation instructions for the default nginx configuration that is required to turn passenger support on:

$ mv nginx.install nginx-passenger.install
$ cat nginx-passenger.install
objs/nginx usr/sbin
html/* var/www/nginx-default
debian/conf/* etc/nginx
debian/passenger.conf etc/nginx/conf.d/
debian/NEWS.Debian usr/share/doc/nginx

nginx.logrotate
Move this file to the correct name based on the package name:

$ mv nginx.logrotate nginx-passenger.logrotate

passenger.conf
Create the following file in the debian directory:

    passenger_root /var/lib/gems/1.8/gems/passenger-2.2.4;
    passenger_ruby /usr/bin/ruby1.8;

Ensure those paths point to the correct passenger isntall and ruby directories.

postinst
Add the following steps to the postinst script after the '#DEBHELPER#' token:

# Phusion Passenger module settings for nginx
echo
echo "***********************************************************************"
echo "For each virtual host you want to add Phusion Passenger support for you"
echo "need to create a config like this in /etc/nginx/site-available:"
echo
echo "    server {
      listen 80;
      server_name DOMAIN_NAME;
      root /var/www/RAILS_PROJECT/public; #<--- be sure to point to 'public'!
      passenger_enabled on;
    }"
echo
echo "Don't forget to add a symlink from this file(s) to"
echo "/etc/nginx/site-enabled to enable the configuration in nginx."
echo "***********************************************************************"
echo

This will warn administrators that install this package that they still need to do some manual work to get a virtual host set up to take advantage of the passenger module.

Package rebuild
The package can then be rebuilt just like any other custom deb:

$ cd /var/tmp/nginx-passenger/nginx-passenger-0.6.35
$ dpkg-buildpackage -rfakeroot
dpkg-buildpackage: set CFLAGS to default value: -g -O2
[...]
dpkg-deb: building package `nginx-passenger' in `../nginx-passenger_0.6.35-0custom1_i386.deb'.
dpkg-deb: ignoring 1 warnings about the control file(s)
 signfile nginx-passenger_0.6.35-0custom1.dsc
gpg: skipped "Charl Matthee ": secret key not available
gpg: [stdin]: clearsign failed: secret key not available

dpkg-genchanges  >../nginx-passenger_0.6.35-0custom1_i386.changes
dpkg-genchanges: warning: the current version (0.6.35-0custom1) is smaller than the previous one (0.6.35-0ubuntu1)
dpkg-genchanges: including full source code in upload
dpkg-buildpackage: full upload; Debian-native package (full source is included)
dpkg-buildpackage: warning: Failed to sign .dsc and .changes file

Those signing errors were triggered because I have did not have the required key infrastructure installed. They can be ignored for the moment.

Install the new package:

$ sudo dpkg -i ../nginx-passenger_0.6.35-0custom1_i386.deb
[...]
Setting up nginx-passenger (0.6.35-0custom1) ...

***********************************************************************
Create a config like this for each virtual host you want to add Phusion
Passenger support to. They should be created in
/etc/nginx/site-available:

    server {
      listen 80;
      server_name DOMAIN_NAME;
      root /var/www/RAILS/public;     # <--- be sure to point to 'public'!
      passenger_enabled on;
    }

Don't forget to add a symlink from this file(s) to
/etc/nginx/site-enabled to enable the configuration in nginx.
***********************************************************************
[...]

Nginx passenger configuration
To enable and take advantage of the passenger nginx module you need to create a /etc/nginx/conf.d/passenger.conf config:

    passenger_root /var/lib/gems/1.8/gems/passenger-2.2.4;
    passenger_ruby /usr/bin/ruby1.8;

This will of course have been done when we installed our custom package.

Next, add a virtual host for each of the rails applications you want to support by dropping a file like 'foo' into /etc/nginx/sites-available/:

    server {
      listen 80;
      server_name foo.example.com;
      root /var/www/foo/public;   # <--- be sure to point to 'public'!
      passenger_enabled on;
    }

Ensure that the port, server_name and root variables have valid values for your environment.

If you want to use a non-production rails environment you can add the following to the block after passenger_enabled:

      rails_env development;

To enable the virtual host(s) you need to ensure that there's a symlink linking the virtual host in sites-available to sites-enabled:

$ sudo ln -s /etc/nginx/sites-available/foo /etc/nginx/sites-enabled/foo
$ ls -la /etc/nginx/sites-enabled
total 8
drwxr-xr-x 2 root root 4096 2009-06-29 12:33 .
drwxr-xr-x 5 root root 4096 2009-06-29 10:51 ..
lrwxrwxrwx 1 root root   34 2009-06-02 07:25 default -> /etc/nginx/sites-available/default
lrwxrwxrwx 1 root root   30 2009-06-29 12:33 foo -> /etc/nginx/sites-available/foo

Once done you can restart nginx and you should see the following processes that confirm things are running:

$ ps axf | egrep "nginx|passenger"
28608 pts/1    S+     0:00                      \_ egrep nginx|passenger
28560 pts/1    Sl     0:00 PassengerNginxHelperServer /var/lib/gems/1.8/gems/passenger-2.2.4 /usr/bin/ruby1.8 3 4 0 6 0 300 1 nobody 33 33 /tmp/passenger.28557
28580 ?        Ss     0:00 nginx: master process /usr/sbin/nginx
28581 ?        S      0:00  \_ nginx: worker process

The final test to see if everything is working is to open a browser and to browse to the server_name and port defined above. Errors will be reported in /var/log/nginx/error.log as well as the development/production logs of the rails project you're running.