= Passenger users guide =
 
image:images/phusion_banner.png[link="http://www.phusion.nl/"]
 
Passenger is an Apache module, which makes deploying Ruby on Rails applications
on Apache a breeze. It follows the usual Ruby on Rails conventions, such as
"Don't-Repeat-Yourself" and ease of setup.
 
This users guide will teach you:
 
- How to install Passenger.
- How to configure Passenger.
- How to deploy a Ruby on Rails application.
- How to solve common problems.
 
This guide assumes that the reader is somewhat familiar with Apache and with
using the commandline.
 
 
== Supported operating systems ==
 
Passenger works on any POSIX-compliant operating system. In other words:
practically any operating system on earth, except Microsoft Windows.
 
Passenger has been tested on:
 
- Ubuntu Linux 6.06 (x86)
- Ubuntu Linux 7.10 (x86)
- Debian Sarge (x86)
- Debian Etch (x86)
- Debian Lenny/Sid (x86)
- CentOS 5 (x86)
- Red Hat Enterprise Linux 5 (x86)
- Gentoo, March 14 2008 (AMD64)
- FreeBSD 6.1-RELEASE (x86)
- MacOS X Tiger (x86)
- MacOS X Leopard (x86)
 
Other operating systems have not been tested, but Passenger will probably work
fine on them. Please
link:http://code.google.com/p/phusion-passenger/issues/list[report a bug]
or
link:http://groups.google.com/group/phusion-passenger[join our discussion list]
if it doesn't.
 
 
== Installing Passenger ==
 
=== Generic installation instructions ===
 
[[install_passenger]]
==== Overview of download and installation methods ====
 
There are two ways to install Passenger:
 
1. By installing the Passenger gem, as instructed on the
   link:http://www.modrails.com/install.html[``Install'' page on the Passenger website].
2. By downloading a native Linux package (e.g. Debian package) from the Passenger website.
3. By downloading the source tarball from the Passenger website
   ('passenger-x.x.x.tar.gz').
 
In our opinion, installing the gem or the native package is easiest.
 
Passenger provides an easy-to-use installer for installing the Passenger
Apache module ('mod_passenger').
 
TIP: You might have to run the installation commands in the following sections
as 'root'. If the installer fails because of permission errors, it will tell
you.
 
[[specifying_correct_apache_install]]
==== Specifying the correct Apache installation ====
 
NOTE: You can skip this section if you've installed Passenger via a native Linux
package, because no compilation is necessary.
 
If your system has multiple Apache installations (this is likely the case on
MacOS X), then you will need to tell the Passenger installer which one to use.
If you only have one Apache installation (the case on most Linux systems), then
you can skip this section because Passenger will automatically detect it.
 
Every Apache installation has its own `apxs` program. You will need to tell
Passenger the location of this program, by specifying the `APXS2` environment
variable. Suppose that you want to use the Apache installation in
'/opt/apache2'. Then, assuming that the corresponding `apxs` program is located
'/opt/apache2/bin/apxs', type:
----------------------------------
export APXS2=/opt/apache2/bin/apxs
----------------------------------
 
NOTE: On some systems, the `apxs` program might be called `apxs2`, and it might
be located in the `sbin` folder instead of the `bin` folder.
 
[[specifying_ruby_installation]]
==== Specifying the correct Ruby installation ====
 
NOTE: You can skip this section if you've installed Passenger via a native Linux
package, because no compilation is necessary.
 
If your system has multiple Ruby installations (this is likely the case on
MacOS X), then you will need to tell the Passenger installer which one to use.
If you only have one Ruby installation (the case on most Linux systems), then
you can skip this section because Passenger will automatically detect it.
 
To specify the Ruby installation, prepend your Ruby installation's `bin`
directory to the `PATH` environment variable. For example, if you have the
following Ruby installations:
 
- /usr/bin/ruby
- /opt/myruby/bin/ruby
 
and you want to use the latter, then type:
 
----------------------------------
export PATH=/opt/myruby/bin:$PATH
----------------------------------
 
 
==== Installing via the gem ====
 
Please install the gem and then run the Passenger installer, by typing the
following commands:
------------------------------------------------------
gem install passenger-x.x.x.gem
passenger-install-apache2-module
------------------------------------------------------
Please follow the instructions given by the installer.
 
==== Installing via a native Linux package ====
 
Please install the native Linux package, e.g.:
------------------------------------------------------
gdebi passenger_x.x.x-i386.deb
------------------------------------------------------
 
Next, you'll need to configure Apache. Run the "installer", as it will tell you
the correct configuration options for Apache:
------------------------------------------------------
passenger-install-apache2-module
------------------------------------------------------
 
NOTE: The installer doesn't actually install anything because it will automatically
detect that Passenger has already been installed. The only thing the installer
will do in this case, is showing the correct Apache configurations.
 
==== Installing via the source tarball ====
 
Extract the tarball to whatever location you prefer. The Passenger files
are to reside in that location permanently. For example, if you would like
Passenger to reside in `/opt/passenger-x.x.x`:
------------------------------------------------------
cd /opt
tar xzvf ~/YourDownloadsFolder/passenger-x.x.x.tar.gz
------------------------------------------------------
 
Next, run the included installer:
------------------------------------------------------
/opt/passenger-x.x.x/bin/passenger-install-apache2-module
------------------------------------------------------
Please follow the instructions given by the installer.
 
IMPORTANT: Please do not remove the 'passenger-x.x.x' folder after
installation. Furthermore, the 'passenger-x.x.x' folder must be accessible by Apache.
 
 
=== Operating system-specific instructions and information ===
 
==== MacOS X ====
 
Ben Ruebenstein has written an excellent
link:http://benr75.com/articles/2008/04/12/setup-mod_rails-phusion-mac-os-x-leopard[tutorial
on installing Phusion Passenger on OS X].
 
==== Ubuntu Linux ====
 
Ben Hughes has written an link:http://www.railsgarden.com/2008/04/12/configurating-passenger-mod_rails-on-slicehost-with-ubuntu-710/[article on installing Passenger on Ubuntu].
 
 
== Deploying a Ruby on Rails application ==
 
Suppose you have a Ruby on Rails application in '/webapps/mycook', and you own
the domain 'www.mycook.com'. You can either deploy your application in the
virtual host's root (i.e. the application will be accessible from the root URL,
'http://www.mycook.com/'), or in a sub URI (i.e. the application will be
accessible from a sub URL, such as 'http://www.mycook.com/railsapplication').
 
NOTE: The default `RAILS_ENV` environment in which deployed Rails applications
are run, is ``production''. You can change this by changing the
<<rails_env,'RailsEnv'>> configuration option.
 
=== Deploying to a virtual host's root ===
 
Add a virtual host entry to your Apache configuration file. The virtual host's
document root must point to your Ruby on Rails application's 'public' folder.
For example:
-------------------------------------------
<VirtualHost *:80>
    ServerName www.mycook.com
    DocumentRoot /webapps/mycook/public
</VirtualHost>
-------------------------------------------
Then restart Apache. The application has now been deployed.
 
[[deploying_to_sub_uri]]
=== Deploying to a sub URI ===
 
Suppose that you already have a virtual host:
 
-------------------------------------------
<VirtualHost *:80>
    ServerName www.phusion.nl
    DocumentRoot /websites/phusion
</VirtualHost>
-------------------------------------------
 
And you want your Ruby on Rails application to be accessible from the URL
'http://www.phusion.nl/rails'.
 
To do this, make a symlink from your Ruby on Rails application's 'public'
folder to a directory in the document root. For example:
-------------------------------------------
ln -s /webapps/mycook/public /websites/phusion/rails
-------------------------------------------
 
Next, add a `RailsBaseURI` option to the virtual host configuration:
-------------------------------------------
<VirtualHost *:80>
    ServerName www.phusion.nl
    DocumentRoot /websites/phusion
    RailsBaseURI /rails                # This line has been added.
</VirtualHost>
-------------------------------------------
Then restart Apache. The application has now been deployed.
 
=== Redeploying (restarting the Ruby on Rails application) ===
 
Deploying a new version of a Ruby on Rails application is as simple as
re-uploading the application files, and restarting the application.
 
There are two ways to restart the application:
 
1. By restarting Apache.
2. By creating or modifying the file 'tmp/restart.txt' in the Rails
   application's root folder. Passenger will automatically restart the
   application.
 
For example, to restart our example MyCook application, we type this in the
command line:
-------------------------------------------
touch /webapps/mycook/tmp/restart.txt
-------------------------------------------
 
=== Migrations ===
 
Passenger is not related to Ruby on Rails migrations in any way. To run
migrations on your deployment server, please login to your deployment server
(e.g. with 'ssh') and type `rake db:migrate RAILS_ENV=production' in a shell
console, just like one normally runs migrations.
 
 
== Configuring Passenger ==
 
After installation, Passenger does not need any further configurations.
Nevertheless, the system administrator may be interested in changing
Passenger's behavior. Passenger's Apache module supports the following
configuration options:
 
RailsSpawnServer <filename>::
  The location to the Passenger spawn server. This configuration option is
  essential to Passenger. The correct value is given by the installer,
  and should usually not be changed manually.
+
This option may only occur once, in the global server configuration. If
this option is not given, then Passenger will look for the program
`passenger-spawn-server` in `$PATH`.
 
RailsBaseURI <uri>::
  Used to specify that the given URI is a Rails application. See
  <<deploying_to_sub_uri,Deploying to a sub URI>> for an example.
+
This option may occur multiple times, in the global server configuration or in a
virtual host configuration block.
 
RailsAutoDetect <on|off>::
  Whether Passenger should automatically detect whether a virtual host's
  document root is a Ruby on Rails application. The default is 'on'.
+
This option may occur in the global server configuration or in a virtual host
configuration block.
+
For example, consider the following configuration:
+
-----------------------------
RailsAutoDetect off
<VirtualHost *:80>
    ServerName www.mycook.com
    DocumentRoot /webapps/mycook/public
</VirtualHost>
-----------------------------
+
If one goes to 'http://www.mycook.com/', the visitor will see the contents of
the '/webapps/mycook/public' folder, instead of the output of the Ruby on Rails
application.
+
It is possible to explicitly specify that the host is a Ruby on Rails
application by using the `RailsBaseURI` configuration option:
+
-----------------------------
RailsAutoDetect off
<VirtualHost *:80>
    ServerName www.mycook.com
    DocumentRoot /webapps/mycook/public
    RailsBaseURI /
</VirtualHost>
-----------------------------
 
[[RailsAllowModRewrite]]
RailsAllowModRewrite <on|off>::
  If enabled, Passenger will not override mod_rewrite rules. Please read
  <<conflicting_apache_modules,Conflicting Apache modules>> for details.
+
This option may occur in the global server configuration or in a virtual host
configuration block. The default value is 'off'.
 
RailsRuby <filename>::
  This option allows one to specify the Ruby interpreter to use.
+
This option may only occur once, in the global server configuration.
The default is 'ruby'.
 
[[rails_env]]
RailsEnv <string>::
  This option allows one to specify the default `RAILS_ENV` value.
+
This option may only occur once, in the global server configuration.
The default is 'production'.
+
TIP: Even though it is not possible to specify a different RailsEnv
per virtual host in the Apache configuration file, one can set the
Rails environment by editing `RAILS_ENV=...` in the application's
'config/environment.rb'.
 
RailsMaxPoolSize <integer>::
  The maximum number of Ruby on Rails application instances that may
  be simultaneously active. A larger number results in higher memory usage,
  but improved ability to handle concurrent HTTP clients.
+
The optimal value depends on your system's hardware and the server's average
load. You should experiment with different values. But generally speaking,
the value should be at least equal to the number of CPUs (or CPU cores) that
you have. If your system has 2 GB of RAM, then we recommend a value of '30'.
If your system is a Virtual Private Server (VPS) and has about 256 MB RAM, and
is also running other services such as MySQL, then we recommend a value of '2'.
+
If you find that your server is unable to handle the load on your Rails websites
(i.e. running out of memory) then you should lower this value. (Though if your
sites are really that popular, then you should strongly consider upgrading your
hardware or getting more servers.)
+
This option may only occur once, in the global server configuration.
The default value is '20'.
+
TIP: We strongly recommend you to <<reducing_memory_usage,use Ruby Enterprise
Edition>>. This allows you to reduce your memory usage by about 33%. And it's
not hard to install.
 
RailsPoolIdleTime <integer>::
  The maximum number of seconds that a Ruby on Rails application instance
  may be idle. That is, if an application instance hasn't done anything after
  the given number of seconds, then it will be shutdown in order to conserve
  memory.
+
Decreasing this value means that Rails applications will have to be spawned
more often. Since spawning is a relatively slow operation, some visitors may
notice a small delay when they visit your Rails site. However, it will also
free up resources used by Rails applications more quickly.
+
The optimal value depends on the average time that a visitor spends on a single
Rails web page. We recommend a value of `2 * x`, where `x` is the average
number of seconds that a visitor spends on a single Rails web page. But your
mileage may vary.
+
This option may only occur once, in the global server configuration.
The default value is '120'.
 
[[RailsUserSwitching]]
RailsUserSwitching <on|off>::
  Whether to enable <<user_switching,user switching support>>.
+
This option may only occur once, in the global server configuration.
The default value is 'on'.
 
[[RailsDefaultUser]]
RailsDefaultUser <username>::
  Passenger enables <<user_switching,user switching support>> by default.
  This configuration option allows one to specify which user Rails
  applications must run as, if user switching fails or is disabled.
+
This option may only occur once, in the global server configuration.
The default value is 'nobody'.
 
 
== Troubleshooting ==
 
=== Operating system-specific problems ===
 
==== MacOS X: The installer cannot locate MAMP's Apache ====
 
.Symptoms
*******************************************************************************
The installer finds Apache 2 development headers at `/Applications/MAMP/Library/bin/apxs`.
However, Apache cannot be found. The installer also outputs the following error:
------------------------------------
cannot open /Applications/MAMP/Library/build/config_vars.mk:
No such file or directory at /Applications/MAMP/Library/bin/apxs line 218.
------------------------------------
*******************************************************************************
 
Your MAMP installation seems to be broken. In particular, 'config_vars.mk' is missing.
Please read link:http://forum.mamp.info/viewtopic.php?t=1866[this forum topic] to learn how
to fix this problem.
 
See also link:http://code.google.com/p/phusion-passenger/issues/detail?id=12[this bug report].
 
 
=== Problems during installation ===
 
[[installing_ruby_dev]]
==== Ruby development headers aren't installed ====
 
.Symptoms
*******************************************************************************
Installing Passenger fails because of one of the following errors:
 
- The Passenger installer tells you that the Ruby development headers aren't
  installed.
- The error message ``'no such file to load -- mkmf''' occurs.
- The error message ``'ruby.h: No such file or directory''' occurs.
*******************************************************************************
 
Passenger makes use of a native extension, so the Ruby development headers
must be installed. On most Linux systems, Ruby and the Ruby development headers
are contained in separate packages, so having Ruby installed does not
automatically imply having the development headers installed.
 
Here's how you can install the development headers:
 
Ubuntu/Debian::
  Please type:
+
-----------------------------------------
sudo apt-get install ruby1.8-dev
-----------------------------------------
 
Fedora/CentOS/RHEL::
  Please type:
+
-----------------------------------------
su -c 'yum install ruby-devel'
-----------------------------------------
 
FreeBSD::
  Please install Ruby from 'ports' or with `pkg_add`. If that fails,
  please install Ruby from source.
 
MacOS X::
  Please install Ruby from source.
 
Other operating systems::
  Please consult your operating system's native package database.
  There should be a package containing the Ruby development headers.
  If that fails, please install Ruby from source.
 
NOTE: If you've installed a new Ruby version (i.e. your system now contains
multiple Ruby installations), then you will need to tell Passenger which Ruby
installation you want to use. Please read
<<specifying_ruby_installation,Specifying the correct Ruby installation>>.
 
==== Apache development headers aren't installed ====
 
.Symptoms
*******************************************************************************
Installing Passenger fails because of one of the following errors:
 
- The installer says that the Apache development headers aren't installed.
- The error message ``'httpd.h: No such file or directory''' occurs.
+
(Instead of 'httpd.h', the message might also be 'http_config.h' or something
else similar to 'http_*.h'.)
*******************************************************************************
 
Ubuntu::
  Please type:
+
-----------------------------------------
sudo apt-get install apache2-prefork-dev
-----------------------------------------
 
Debian::
  Please type:
+
-----------------------------------------
sudo apt-get install apache2-dev
-----------------------------------------
 
Fedora/CentOS/RHEL::
  Please type:
+
--------------------------------
su -c 'yum install httpd-devel'
--------------------------------
 
FreeBSD::
  Please install Apache from 'ports' or with `pkg_add`. If that fails,
  please install Apache from source.
 
MacOS X::
  Please install Apache from source.
 
Other operating systems::
  Please consult your operating system's native package database.
  There should be a package containing the Apache development headers.
  If that fails, please install Apache from source.
 
 
==== APR development headers aren't installed ====
 
.Symptoms
*******************************************************************************
Installing Passenger fails because one of the following errors:
 
- The installer tells you that APR development headers aren't installed.
- The error message ``'apr_pools.h: No such file or directory''' occurs.
- The error message ``'apr_strings.h: No such file or directory''' occurs.
*******************************************************************************
 
Ubuntu::
  Please type:
+
-----------------------------------------
sudo apt-get install libapr1-dev
-----------------------------------------
 
Debian::
  Please type:
+
-----------------------------------------
sudo apt-get install libapr1-dev
-----------------------------------------
 
Fedora/CentOS/RHEL::
  Please type:
+
--------------------------------
su -c 'yum install apr-devel'
--------------------------------
 
Other Linux distributions::
  Please consult your distribution's package database. There should be a
  package which provides APR development headers.
 
Other operating systems::
  The APR development are bundled with Apache. If the APR headers aren't,
  then it probably means that they have been removed after Apache's been
  installed. Please reinstall Apache to get back the APR headers.
 
 
==== Passenger is using the wrong Apache during installation ====
 
Please <<specifying_correct_apache_install,Specifying the correct Apache
installation>>, and re-run the Passenger installer.
 
 
==== Passenger is using the wrong Ruby during installation ====
 
Please <<specifying_ruby_installation,Specifying the correct Ruby
installation>>, and re-run the Passenger installer.
 
 
=== Problems after installation ===
 
[TIP]
.The golden tip: read your Apache error logs!
=====================================================
'mod_passenger' will write all errors to the Apache error log. So if
you're experiencing post-installation problems, please look
inside the Apache error logs. It will tell you what exactly went wrong.
=====================================================
 
==== Passenger has been compiled against the wrong Apache installation ====
 
.Symptoms
*******************************************************************************
Apache crashes during startup (after being daemonized). The Apache error log
says ``'seg fault or similar nasty error detected in the parent process'''.
*******************************************************************************
 
This problem is most likely to occur on MacOS X. Most OS X users have multiple
Apache installations on their system.
 
To solve this problem, please <<specifying_correct_apache_install,specify the
correct Apache installation>>, and <<install_passenger,reinstall Passenger>>.
 
==== I get a "304 Forbidden" error ====
 
See next subsection.
 
==== Static assets such as images and stylesheets aren't being displayed ====
 
Static assets are accelerated, i.e. they are served directly by Apache and do not
go through the Rails stack. There are two reasons why Apache doesn't serve static
assets correctly:
 
1. Your Apache configuration is too strict, and does not allow HTTP clients to
   access static assets. This can be achieved with an `Allow from all` directive
   in the correct place. For example:
+
-----------------------------------------
<Directory "/webapps/mycook/public">
   Options FollowSymLinks
   AllowOverride None
   Order allow,deny
   Allow from all
</Directory>
-----------------------------------------
+
See also link:http://groups.google.com/group/phusion-passenger/browse_thread/thread/9699a639a87f85f4/b9d71a03bf2670a5[this discussion].
 
2. The Apache process doesn't have permission to access your Rails application's folder.
   Please make sure that the Rails application's folder, as well as all of its parent folders,
   have the correct permissions and/or ownerships.
 
==== The Apache error log says that the spawn manager script does not exist, or that it does not have permission to execute it ====
 
If you are sure that the RailsSpawnServer configuration option is set correctly,
then this problem is most likely caused by the fact that you're running Apache
with SELinux. On Fedora, CentOS and RedHat Enterprise Linux, Apache is locked
down by SELinux policies.
 
To solve this problem, you must set some permissions on the Passenger files and
folders, so that Apache can access them.
 
- If you've installed Passenger via a gem, then run this command to determine
  Passenger's root folder:
+
------------------------------------------------------------------
passenger-config --root
------------------------------------------------------------------
+
Next, run the following command:
+
------------------------------------------------------------------
chcon -R -h -t httpd_sys_content_t /path-to-passenger-root
------------------------------------------------------------------
+
where '/path-to-passenger-root' should be replaced with whatever
`passenger-config --root` printed.
 
- If you've installed Passenger via the source tarball, then run the following
  command:
+
------------------------------------------------------------------
chcon -R -h -t httpd_sys_content_t /path/to/passenger/folder
------------------------------------------------------------------
 
Once the permissions are fixed, restart Apache.
 
==== The Rails application reports that it's unable to start because of a permission error ====
 
Please check whether your Rails application's folder has the correct
permissions. By default, Rails applications are started as the owner of the
file 'config/environment.rb', except if the file is owned by root. If the
file is owned by root, then the Rails application will be started as 'nobody'
(or as the user specify by <<RailsDefaultUser,RailsDefaultUser>>, if that's
specified).
 
Please read <<user_switching,User switching (security)>> for details.
 
==== My Rails application's log file is not being written to ====
 
There are a couple things that you should be aware of:
 
- By default, Passenger runs Rails applications in 'production' mode, so please
  be sure to check 'production.log' instead of 'development.log'. See
  <<RailsEnv,RailsEnv>> for configuration.
- By default, Passenger runs Rails applications as the owner of 'environment.rb'.
  So the log file can only be written to if that user has write permission to the
  log file. Please 'chmod' or 'chown' your log file accordingly.
+
See <<User_switching,User switching (security)>> for details.
 
If you're using a RedHat-derived Linux distribution (such as Fedora or CentOS)
then it is link:http://code.google.com/p/phusion-passenger/issues/detail?id=4[possible
that SELinux is interfering]. RedHat's SELinux policy only allows Apache to read/write
directories that have the 'httpd_sys_content_t' security context. Please run the
following command to give your Rails application folder that context:
 
-----------------------------------------------------------
chcon -R -h -t httpd_sys_content_t /path/to/your/rails/app
-----------------------------------------------------------
 
[[conflicting_apache_modules]]
=== Conflicting Apache modules ===
 
==== mod_rewrite and mod_alias ====
 
Passenger conflicts with 'mod_rewrite' and 'mod_alias'. Those modules may be
installed and loaded together with 'mod_passenger', and they will work fine
outside virtual hosts that contain a Rails application, but we recommend you
not to use their features inside virtual hosts that contain a Rails
application.
 
By default, Passenger will override mod_rewrite rules on Rails hosts. This is
because the default .htaccess, as provided by Ruby on Rails, redirects all
requests to `dispatch.cgi' using mod_rewrite. This is a CGI application which
loads the entire Ruby on Rails framework for every request, and thus is very
slow. If we do not override mod_rewrite, then Ruby on Rails apps will be slow
on Passenger by default -- but we want a good out-of-the-box experience.
 
Furthermore, the primary reason why people use mod_rewrite with Rails
applications, is to accelerate page caching. Passenger supports page caching
out-of-the-box, without mod_rewrite.
 
It is not fully understood how mod_alias conflicts with Passenger, but we
recommend you not to use it on Rails virtual hosts. mod_alias rules can result
in surprising problems.
 
If you really want to use mod_rewrite on Rails virtual hosts, then please set
the <<RailsAllowModRewrite,RailsAllowModRewrite>> configuration option. But
please note that you will have to delete Rails applications' default .htaccess
file, or add rewrite rules to negate its effects.
 
==== mod_userdir ====
 
'mod_userdir' is not compatible with Phusion Passenger at the moment.
 
==== VirtualDocumentRoot ====
 
VirtualDocumentRoot is not compatible with Phusion Passenger at the moment.
 
 
== Tips and notes ==
 
[[user_switching]]
=== User switching (security) ===
 
There is a problem that plagues most PHP web host, namely the fact that all PHP
applications are run in the same user context as the web server. So for
example, Joe's PHP application will be able to read Jane's PHP application's
passwords. This is obviously undesirable on many servers.
 
Passenger solves this problem by implementing 'user switching'. A Rails
application is started as the owner of the file 'config/environment.rb'. So if
'/home/webapps/foo/config/environment.rb' is owned by 'joe', then Passenger
will launch the corresponding Rails application as 'joe' as well.
 
This behavior is the default, and you don't need to configure anything. But
there are things that you should keep in mind:
 
- The owner of 'environment.rb' must have read access to the Rails application's
  folder, and read/write access to the Rails application's 'logs' folder.
- This feature is only available if Apache is started by 'root'. This is the
  case on most Apache installations.
- Under no circumstances will Rails 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
  <<RailsDefaultUser,RailsDefaultUser>>.
 
User switching can be disabled with the
<<RailsUserSwitching,RailsUserSwitching>> option.
 
 
[[reducing_memory_usage]]
=== Reducing memory consumption of Ruby on Rails apps by 33% ===
 
Is it possible to reduce memory consumption of your Rails apps by 33% on average,
by using http://www.rubyenterpriseedition.com/[Ruby Enterprise Edition].
Please visit the website for details.
 
=== Moving Passenger to a different directory ===
 
It is possible to relocate the Passenger files to a different directory. It
involves two steps:
 
1. Moving the directory.
2. Updating the ``RailsSpawnServer'' configuration option in Apache.
 
For example, if Passenger is located in '/opt/passenger/', and you'd like to
move it to '/usr/local/passenger/', then do this:
 
1. Run the following command:
+
------------------------------------
mv /opt/passenger /usr/local/passenger
------------------------------------
2. Edit your Apache configuration file, and set:
+
------------------------------------
RailsSpawnServer /usr/local/passenger/bin/passenger-spawn-server
------------------------------------
 
=== Installing multiple Ruby on Rails versions ===
 
Each Ruby on Rails applications that are going to be deployed may require a
specific Ruby on Rails version. You can install a specific version with
this command:
-----------------------------
gem install rails -v X.X.X
-----------------------------
where 'X.X.X' is the version number of Ruby on Rails.
 
All of these versions will exist in parallel, and will not conflict with each
other. Passenger will automatically make use of the correct version.
 
=== X-Sendfile support ===
 
Passenger does not provide X-Sendfile support by itself. Please install
link:http://tn123.ath.cx/mod_xsendfile/[mod_xsendfile] for X-Sendfile support.
 
 
== Appendix A: About this document ==
 
The text of this document is licensed under the
link:http://creativecommons.org/licenses/by-sa/3.0/[Creative Commons
Attribution-Share Alike 3.0 Unported License].
 
image:images/by_sa.png[link="http://creativecommons.org/licenses/by-sa/3.0/"]
 
Passenger is brought to you by Phusion.
 
image:images/phusion_banner.png[link="http://www.phusion.nl/"]