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Users guide Apache.txt
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Users guide Apache.txt
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= Phusion Passenger users guide =
image:images/phusion_banner.png[link="http://www.phusion.nl/"]
Phusion Passenger is an Apache module, which makes deploying Ruby and 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, while at the
same time providing enough flexibility.
This users guide will teach you:
- How to install Phusion Passenger.
- How to configure Phusion Passenger.
- How to deploy a Ruby on Rails application.
- How to deploy a link:http://rack.rubyforge.org/[Rack]-based Ruby 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 ==
Phusion Passenger works on any POSIX-compliant operating system. In other
words: practically any operating system on earth, except Microsoft Windows.
Phusion Passenger is confirmed on a large number of operating systems and Linux
distributions, including, but not limited to, Ubuntu, Debian, CentOS/Fedora/RHEL,
Gentoo, Mac OS X, FreeBSD and Solaris. Both 32-bit and 64-bit platforms are supported.
The only POSIX-compliant operating system on which Phusion Passenger for Apache is
known not to work at this time, is OpenBSD. Please use Phusion Passenger for Nginx
instead.
If Phusion Passenger does not work on your platform then 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].
== Installing, upgrading and uninstalling Phusion Passenger ==
=== Generic installation instructions ===
[[install_passenger]]
==== Overview of installation methods ====
There are three ways to install Phusion Passenger:
1. By installing the Phusion Passenger gem, as instructed on the
link:http://www.modrails.com/install.html[``Install'' page on the Phusion
Passenger website].
2. By downloading the source tarball from the Phusion Passenger website
('passenger-x.x.x.tar.gz').
3. By installing a native Linux package (e.g. Debian package).
The following sections will explain each installation method. Please read the
section for the installation method that you prefer. In our opinion, installing
the gem or the native package is easiest. For these two installation methods,
Phusion Passenger provides an easy-to-use installer.
==== Preparation (gem and source tarball only)
If you want to install Phusion Passenger via the gem or the source tarball,
then some preparations might be required. You can skip this subsection if
you're installing Phusion Passenger via a native Linux package, because no
compilation is necessary.
===== Switching to a root command prompt =====
Before installing, you will probably need to switch to the `root` user first.
When you install Phusion Passenger via a gem or a source tarball, some Phusion
Passenger files have to be compiled, which requires write access to the
directory in which the Phusion Passenger files are located. On Unix systems,
the root user is the user who has write access to the entire system. So unless
you know that your normal user account has write access to the Phusion Passenger
directory, you should switch to root before installing Phusion Passenger.
You can switch to root by typing the following command:
-------------------------
sudo -s
-------------------------
This will open a command prompt as the root user, from which you can proceed
with installing Phusion Passenger.
If your system does not have 'sudo' installed, please type the following command instead, which should do the same thing:
-------------------------
su
-------------------------
[[specifying_correct_apache_install]]
===== Specifying the correct Apache installation =====
The Phusion Passenger installer will attempt to automatically detect Apache,
and compile Phusion Passenger against that Apache version. It does this by
looking for the `apxs` or `apxs2` command in the PATH environment variable.
Apxs is an integral part of any Apache installation.
However, some systems have multiple Apache installations. This is likely
the case on MacOS X: the OS ships with Apache, but users tend to install
another Apache version seperately, e.g. via MacPorts. If your system has
multiple Apache installations, then you will need to tell the Phusion Passenger
installer which one to use. It is very important that you specify the
correct Apache installation, because if you load Phusion Passenger in an
Apache installation that it wasn't compiled against, then it will likely
crash.
On yet other systems, Apache is installed in a non-standard location,
preventing the Phusion Passenger installer from detecting Apache. This
is most likely the case on systems on which Apache was installed by hand
from source, i.e. as opposed to installed through the system's native
package manager. If this is the case, then you will also have to tell
the installer where it can find Apache.
To do so, set the `APXS2` environment variable to the full path of the
correct `apxs` or `apxs2` command. Suppose that you want to use the Apache
installation in '/opt/apache2'. Then, assuming that the corresponding
`apxs` program's path is '/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.
.Environment variables and 'sudo'
NOTE: By default, the 'sudo' command will erase any environment variables that it
doesn't recognize, prior to executing the given command. So if you set APXS2 as a
normal user, then run `sudo passenger-install-apache2-module` (which is the command
for the Phusion Passenger installer), then the installer will not receive the
environment variable value that you set. To solve this problem, please become root
prior to setting any environment variables, as described in the previous subsection.
[[specifying_ruby_installation]]
===== Specifying the correct Ruby installation =====
If your system has multiple Ruby installations -- which is likely the case on
MacOS X, or if you've also installed
link:http://www.rubyenterpriseedition.com[Ruby Enterprise Edition] -- then you
will need to tell the operating system which Ruby installation to use, prior to
running the Phusion Passenger installer. If you only have one Ruby installation
(the case on most Linux systems), then you can skip this section because Phusion
Passenger will automatically detect it.
To specify a 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 Phusion 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 the source tarball ====
Extract the tarball to whatever location you prefer. *The Phusion Passenger files
are to reside in that location permanently.* For example, if you would like
Phusion 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.
==== Installing via a native Linux package ====
John Leach from Brightbox has kindly provided an Ubuntu Hardy package for Phusion Passenger. The package is available from the link:http://apt.brightbox.net[Brightbox repository].
Please install the native Linux package, e.g.:
------------------------------------------------------
sudo sh -c 'echo "deb http://apt.brightbox.net hardy main" > /etc/apt/sources.list.d/brightbox.list'
sudo sh -c 'wget -q -O - http://apt.brightbox.net/release.asc | apt-key add -'
sudo apt-get update
sudo apt-get install libapache2-mod-passenger
------------------------------------------------------
==== What does the installer do? ====
Although we call it an ``installer'', it doesn't actually install anything.
The installer checks whether all required dependencies are installed,
compiles Phusion Passenger for you, and tells you how to modify the Apache
configuration file, but it doesn't copy any files around.
`passenger-install-apache2-module` is actually just a user-friendly frontend
around the command `rake apache2`, which performs the actual compilation of
Phusion Passenger.
=== 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 Phusion Passenger on Ubuntu].
==== OpenSolaris ====
J Aaron Farr has written a link:http://cubiclemuses.com/cm/articles/2009/04/09/rails-passenger-open-solaris-ec2/[guide]
about setting up Ruby on Rails and Phusion Passenger on OpenSolaris and EC2.
=== Upgrading or downgrading Phusion Passenger ===
==== Via a gem or a source tarball ====
To ugrade or downgrade Phusion Passenger via the gem or the source tarball, install the newer
or older version as you normally would; that is, install the gem or unpack the tarball, and
run `passenger-install-apache2-module`. Eventually `passenger-install-apache2-module` will tell
you to copy & paste some settings into the Apache configuration file; something that looks along
the lines of:
-----------------------------------
LoadModule passenger_module ...
PassengerRoot ...
PassengerRuby ...
-----------------------------------
Because you already have Phusion Passenger installed, you already have the same settings
in your Apache configuration file, just with different values. Replace the old settings with
the new ones that the installer outputs.
When you're done, restart Apache.
==== Via a native Linux package
There are no special instructions required to upgrade or downgrade Phusion Passenger
via a native Linux package.
=== Unloading (disabling) Phusion Passenger from Apache without uninstalling it ===
You can temporarily unload (disable) Phusion Passenger from Apache, without
uninstalling the Phusion Passenger files, so that Apache behaves as if Phusion
Passenger was never installed in the first place. This might be useful to you if,
for example, you seem to be experiencing a problem caused by Phusion Passenger,
but you want to make sure whether that's actually the case, without having
to through the hassle of uninstalling Phusion Passenger completely.
To unload Phusion Passenger from Apache, edit your Apache configuration file(s)
and comment out:
- all Phusion Passenger configuration directives.
- the 'LoadModule passenger_module' directive.
For example, if your configuration file looks like this...
-----------------------------------
Listen *:80
NameVirtualHosts *:80
....
LoadModule passenger_module /somewhere/passenger-x.x.x/ext/apache2/mod_passenger.so
PassengerRuby /usr/bin/ruby
PassengerRoot /somewhere/passenger/x.x.x
PassengerMaxPoolSize 10
<VirtualHost *:80>
ServerName www.foo.com
DocumentRoot /webapps/foo/public
RailsBaseURI /rails
</VirtualHost>
-----------------------------------
...then comment out the relevant directives, so that it looks like this:
-----------------------------------
Listen *:80
NameVirtualHosts *:80
....
# LoadModule passenger_module /somewhere/passenger-x.x.x/ext/apache2/mod_passenger.so
# PassengerRuby /usr/bin/ruby
# PassengerRoot /somewhere/passenger/x.x.x
# PassengerMaxPoolSize 10
<VirtualHost *:80>
ServerName www.foo.com
DocumentRoot /webapps/foo/public
# RailsBaseURI /rails
</VirtualHost>
-----------------------------------
After you've done this, save the file and restart Apache.
=== Uninstalling Phusion Passenger ===
To uninstall Phusion Passenger, please first remove all Phusion Passenger
configuration directives from your Apache configuration file(s). After you've
done this, you need to remove the Phusion Passenger files.
- If you installed Phusion Passenger via a gem, then type `gem uninstall passenger`.
You might have to run this as root.
- If you installed Phusion Passenger via a source tarball, then remove the directory
in which you placed the extracted Phusion Passenger files. This directory is the
same as the one pointed to the by 'PassengerRoot' configuration directive.
- If you installed Phusion Passenger via a Debian package, then remove type
`sudo apt-get remove libapache2-mod-passenger`.
== 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 to 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>
-------------------------------------------
You may also need to tweak your file/folder permissions. Make sure that the
following folders are readable and executable by Apache:
* this 'public' folder.
* the application's 'config' folder.
* all parent folders. That is, /webapps/mycook and /webapps must also be readable and executable by Apache.
Then restart Apache. The application has now been deployed.
[[deploying_rails_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,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.
NOTE: If you're deploying to a sub-URI then please make sure that your view
templates correctly handles references to sub-URI static assets! Otherwise
you may find broken links to images, CSS files, JavaScripts, etc. Please read
<<sub_uri_deployment_uri_fix,How to fix broken images/CSS/JavaScript URIs in sub-URI deployments>>
for more information.
[TIP]
======================================
You can deploy multiple Rails applications under a virtual host, by specifying
<<RailsBaseURI,RailsBaseURI>> multiple times. For example:
---------------------------------
<VirtualHost *:80>
....
RailsBaseURI /app1
RailsBaseURI /app2
RailsBaseURI /app3
</VirtualHost>
---------------------------------
======================================
=== 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 <<application_root,root folder>>. Phusion Passenger will
automatically restart the application during the next request.
For example, to restart our example MyCook application, we type this in the
command line:
-------------------------------------------
touch /webapps/mycook/tmp/restart.txt
-------------------------------------------
Please note that, unlike earlier versions of Phusion Passenger, 'restart.txt'
is not automatically deleted. Phusion Passenger checks whether the timestamp
of this file has changed in order to determine whether the application should
be restarted.
=== Migrations ===
Phusion 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 would normally run migrations.
=== Capistrano integration ===
See <<capistrano,Capistrano recipe>>.
== Deploying a Rack-based Ruby application ==
Phusion Passenger supports arbitrary Ruby web applications that follow the
link:http://rack.rubyforge.org/[Rack] interface.
Phusion Passenger assumes that Rack application directories have a certain layout.
Suppose that you have a Rack application in '/webapps/rackapp'. Then that
folder must contain at least three entries:
- 'config.ru', a Rackup file for starting the Rack application. This file must contain
the complete logic for initializing the application.
- 'public/', a folder containing public static web assets, like images and stylesheets.
- 'tmp/', used for 'restart.txt' (our application restart mechanism). This will
be explained in a following subsection.
So '/webapps/rackapp' must, at minimum, look like this:
----------------------
/webapps/rackapp
|
+-- config.ru
|
+-- public/
|
+-- tmp/
----------------------
Suppose you own the domain 'www.rackapp.com'. You can either deploy your application
to the virtual host's root (i.e. the application will be accessible from the root URL,
'http://www.rackapp.com/'), or in a sub URI (i.e. the application will be
accessible from a sub URL, such as 'http://www.rackapp.com/rackapp').
NOTE: The default `RACK_ENV` environment in which deployed Rack applications
are run, is ``production''. You can change this by changing the
<<rack_env,'RackEnv'>> configuration option.
=== Tutorial/example: writing and deploying a Hello World Rack application ===
First we create a Phusion Passenger-compliant Rack directory structure:
-------------------------------------------
$ mkdir /webapps/rack_example
$ mkdir /webapps/rack_example/public
$ mkdir /webapps/rack_example/tmp
-------------------------------------------
Next, we write a minimal "hello world" Rack application:
-------------------------------------------
$ cd /webapps/rack_example
$ some_awesome_editor config.ru
...type in some source code...
$ cat config.ru
app = proc do |env|
[200, { "Content-Type" => "text/html" }, ["hello <b>world</b>"]]
end
run app
-------------------------------------------
Finally, we deploy it by adding the following configuration options to
the Apache configuration file:
-------------------------------------------
<VirtualHost *:80>
ServerName www.rackexample.com
DocumentRoot /webapps/rack_example/public
</VirtualHost>
-------------------------------------------
And we're done! After an Apache restart, the above Rack application will be available
under the URL 'http://www.rackexample.com/'.
=== 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 Rack application's 'public' folder.
For example:
-------------------------------------------
<VirtualHost *:80>
ServerName www.rackapp.com
DocumentRoot /webapps/rackapp/public
</VirtualHost>
-------------------------------------------
You may also need to tweak your file/folder permissions. Make sure that the
following folders are readable and executable by Apache:
* this 'public' folder.
* the application's 'config' folder.
* all parent folders. That is, /webapps/rackapp and /webapps must also be readable and executable by Apache.
Then restart Apache. The application has now been deployed.
[[deploying_rack_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 Rack application to be accessible from the URL
'http://www.phusion.nl/rack'.
To do this, make a symlink from your Rack application's 'public'
folder to a directory in the document root. For example:
-------------------------------------------
ln -s /webapps/rackapp/public /websites/phusion/rack
-------------------------------------------
Next, add a <<RackBaseURI,RackBaseURI>> option to the virtual host configuration:
-------------------------------------------
<VirtualHost *:80>
ServerName www.phusion.nl
DocumentRoot /websites/phusion
RackBaseURI /rack # This line has been added.
</VirtualHost>
-------------------------------------------
Then restart Apache. The application has now been deployed.
[TIP]
======================================
You can deploy multiple Rack applications under a virtual host, by specifying
<<RackBaseURI,RackBaseURI>> multiple times. For example:
---------------------------------
<VirtualHost *:80>
....
RackBaseURI /app1
RackBaseURI /app2
RackBaseURI /app3
</VirtualHost>
---------------------------------
======================================
=== Redeploying (restarting the Rack application) ===
Deploying a new version of a Rack 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 Rack
application's <<application_root,root folder>>. Phusion Passenger will
automatically restart the application.
For example, to restart our example application, we type this in the
command line:
-------------------------------------------
touch /webapps/rackapp/tmp/restart.txt
-------------------------------------------
=== Rackup specifications for various web frameworks ===
include::users_guide_snippets/rackup_specifications.txt[]
== Configuring Phusion Passenger ==
After installation, Phusion Passenger does not need any further configurations.
Nevertheless, the system administrator may be interested in changing
Phusion Passenger's behavior. Phusion Passenger's Apache module supports the
following configuration options:
=== PassengerRoot <directory> ===
The location to the Phusion Passenger root directory. This configuration option
is essential to Phusion Passenger, and allows Phusion Passenger to locate its own
data files. The correct value is given by the installer.
If you've moved Phusion Passenger to a different directory then you need to update
this option as well. Please read
<<moving_phusion_passenger,Moving Phusion Passenger to a different directory>> for more information.
This required option may only occur once, in the global server configuration.
=== PassengerLogLevel <integer> ===
This option allows one to specify how much information Phusion Passenger should
write to the Apache error log file. A higher log level value means that more
information will be logged.
Possible values are:
- '0': Show only errors and warnings.
- '1': Show the most important debugging information. This might be useful for
system administrators who are trying to figure out the cause of a
problem.
- '2': Show more debugging information. This is typically only useful for developers.
- '3': Show even more debugging information.
This option may only occur once, in the global server configuration.
The default is '0'.
[[PassengerRuby]]
=== PassengerRuby <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'.
[[PassengerAppRoot]]
=== PassengerAppRoot <path/to/root> ===
By default, Phusion Passenger assumes that the application's root directory
is the parent directory of the 'public' directory. This option allows one to
specify the application's root independently from the DocumentRoot, which
is useful if the 'public' directory lives in a non-standard place.
This option may occur in the following places:
* In the global server configuration.
* In a virtual host configuration block.
* In a `<Directory>` or `<Location>` block.
* In '.htaccess', if `AllowOverride Options` is on.
In each place, it may be specified at most once.
Example:
-----------------------------
<VirtualHost test.host>
DocumentRoot /var/rails/zena/sites/example.com/public
PassengerAppRoot /var/rails/zena # <-- normally Phusion Passenger would
# have assumed that the application
# root is "/var/rails/zena/sites/example.com"
</VirtualHost>
-----------------------------
[[PassengerResolveSymlinksInDocumentRoot]]
=== PassengerResolveSymlinksInDocumentRoot <on|off> ===
Configures whether Phusion Passenger should resolve symlinks in the document root.
Please refer to <<application_detection,How Phusion Passenger detects whether a
virtual host is a web application>> for more information.
This option may occur in the following places:
* In the global server configuration.
* In a virtual host configuration block.
* In a `<Directory>` or `<Location>` block.
* In '.htaccess', if `AllowOverride Options` is on.
In each place, it may be specified at most once. It is off by default.
[[PassengerUseGlobalQueue]]
=== PassengerUseGlobalQueue <on|off> ===
Turns the use of global queuing on or off.
This option may occur in the following places:
* In the global server configuration.
* In a virtual host configuration block.
In each place, it may be specified at most once. The default value is 'off'.
'This feature is sponsored by http://www.37signals.com/[37signals].'
include::users_guide_snippets/global_queueing_explained.txt[]
[[PassengerUserSwitching]]
=== PassengerUserSwitching <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'.
[[PassengerDefaultUser]]
=== PassengerDefaultUser <username> ===
Phusion Passenger enables <<user_switching,user switching support>> by default.
This configuration option allows one to specify which user Rails/Rack
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'.
[[PassengerHighPerformance]]
=== PassengerHighPerformance <on|off> ===
By default, Phusion Passenger is compatible with mod_rewrite and most other
Apache modules. However, a lot of effort is required in order to be compatible.
If you turn 'PassengerHighPerformance' to 'on', then Phusion Passenger will be
a little faster, in return for reduced compatibility with other Apache modules.
In places where 'PassengerHighPerformance' is turned on, mod_rewrite rules will
likely not work. mod_autoindex (the module which displays a directory index)
will also not work. Other Apache modules may or may not work, depending on what
they exactly do. We recommend you to find out how other modules behave in high
performance mode via testing.
This option is *not* an all-or-nothing global option: you can enable high
performance mode for certain virtual hosts or certain URLs only.
The 'PassengerHighPerformance' option may occur in the following places:
* In the global server configuration.
* In a virtual host configuration block.
* In a `<Directory>` or `<Location>` block.
* In '.htaccess'.
In each place, it may be specified at most once. The default value is 'off',
so high performance mode is disabled by default, and you have to explicitly
enable it.
.When to enable high performance mode?
If you do not use mod_rewrite or other Apache modules then it might make
sense to enable high performance mode.
It's likely that some of your applications depend on mod_rewrite or other
Apache modules, while some do not. In that case you can enable high performance
for only those applications that don't use other Apache modules. For example:
------------------------------------
<VirtualHost *:80>
ServerName www.foo.com
DocumentRoot /apps/foo/public
.... mod_rewrite rules or options for other Apache modules here ...
</VirtualHost>
<VirtualHost *:80>
ServerName www.bar.com
DocumentRoot /apps/bar/public
PassengerHighPerformance on
</VirtualHost>
------------------------------------
In the above example, high performance mode is only enabled for www.bar.com.
It is disabled for everything else.
If your application generally depends on mod_rewrite or other Apache modules,
but a certain URL that's accessed often doesn't depend on those other modules,
then you can enable high performance mode for a certain URL only. For example:
------------------------------------
<VirtualHost *:80>
ServerName www.foo.com
DocumentRoot /apps/foo/public
.... mod_rewrite rules or options for other Apache modules here ...
<Location /chatroom/ajax_update_poll>
PassengerHighPerformance on
</Location>
</VirtualHost>
------------------------------------
This enables high performance mode for
http://www.foo.com/chatroom/ajax_update_poll only.
=== PassengerEnabled <on|off> ===
You can set this option to 'off' to completely disable Phusion Passenger for
a certain location. This is useful if, for example, you want to integrate a PHP
application into the same virtual host as a Rails application.
Suppose that you have a Rails application in '/apps/foo'. Suppose that you've
dropped Wordpress -- a blogging application written in PHP -- in
'/apps/foo/public/wordpress'. You can then configure Phusion Passenger as
follows:
------------------------------------
<VirtualHost *:80>
ServerName www.foo.com
DocumentRoot /apps/foo/public
<Directory /apps/foo/public/wordpress>
PassengerEnabled off
AllowOverride all # <-- Makes Wordpress's .htaccess file work.
</Directory>
</VirtualHost>
------------------------------------
This way, Phusion Passenger will not interfere with Wordpress.
'PassengerEnabled' may occur in the following places:
* In the global server configuration.
* In a virtual host configuration block.
* In a `<Directory>` or `<Location>` block.
* In '.htaccess'.
In each place, it may be specified at most once. The default value is 'on'.
[[PassengerTempDir]]
=== PassengerTempDir <directory> ===
Specifies the directory that Phusion Passenger should use for storing temporary
files. This includes things such as Unix socket files, buffered file uploads
(see also <<PassengerUploadBufferDir,PassengerUploadBufferDir>>), etc.
This option may be specified once, in the global server configuration. The
default temp directory that Phusion Passenger uses is '/tmp'.
This option is especially useful if Apache is not allowed to write to /tmp
(which is the case on some systems with strict SELinux policies) or if the
partition that /tmp lives on doesn't have enough disk space.
.Command line tools
Some Phusion Passenger command line administration tools, such as
`passenger-status`, must know what Phusion Passenger's temp directory is
in order to function properly. You can pass the directory through the
`PASSENGER_TMPDIR` environment variable, or the `TMPDIR` environment variable
(the former will be used if both are specified).
For example, if you set 'PassengerTempDir' to '/my_temp_dir', then invoke
`passenger-status` after you've set the `PASSENGER_TMPDIR` or `TMPDIR`
environment variable, like this:
----------------------------------------------------------
export PASSENGER_TMPDIR=/my_temp-dir
sudo -E passenger-status
# The -E option tells 'sudo' to preserve environment variables.
----------------------------------------------------------
[[PassengerUploadBufferDir]]
=== PassengerUploadBufferDir <directory> ===
Phusion Passenger buffers large file uploads to disk in order prevent slow file
uploads from blocking web applications. By default, a subdirectory in the
system's temporary files directory (or a subdirectory in the directory specified
in <<PassengerTempDir,PassengerTempDir>>, if set) is automatically created for
storing these buffered file uploads.
This configuration directive allows you to specify a different directory for storing
buffered file uploads. If you've specified such a directory (as opposed to using
Phusion Passenger's default) then you *must* ensure that this directory exists.
This configuration directive is also useful if you're using apache2-mpm-itk.
The buffered file upload directory that Phusion Passenger creates by default has
very strict permissions: it can only be accessed by the Apache worker processes.
However, Phusion Passenger assumes that all Apache worker processes are running
as the same user. apache2-mpm-itk breaks this assumption by running multiple
Apache worker processes as different users. So if you're using apace2-mpm-itk,
you should set this option to a directory that is writable by all Apache worker
processes, such as '/tmp'.
You may specify 'PassengerUploadBufferDir' in the following places:
* In the global server configuration.
* In a virtual host configuration block.
* In a `<Directory>` or `<Location>` block.
* In '.htaccess', if `AllowOverrides Options` is enabled.
In each place, it may be specified at most once.
=== PassengerRestartDir <directory> ===
As described in the deployment chapters of this document, Phusion Passenger
checks the file 'tmp/restart.txt' in the applications'
<<application_root,root directory>> for restarting applications. Sometimes it
may be desirable for Phusion Passenger to look in a different directory instead,
for example for security reasons (see below). This option allows you to
customize the directory in which 'restart.txt' is searched for.
You may specify 'PassengerRestartDir' in the following places:
* In the global server configuration.
* In a virtual host configuration block.
* In a `<Directory>` or `<Location>` block.
* In '.htaccess', if `AllowOverrides Options` is enabled.
In each place, it may be specified at most once.
You can either set it to an absolute directory, or to a directory relative to
the <<application_root,application root>>. Examples:
-----------------------------------
<VirtualHost *:80>
ServerName www.foo.com
# Phusion Passenger will check for /apps/foo/public/tmp/restart.txt
DocumentRoot /apps/foo/public
</VirtualHost>
<VirtualHost *:80>
ServerName www.bar.com
DocumentRoot /apps/bar/public
# An absolute filename is given; Phusion Passenger will
# check for /restart_files/bar/restart.txt
PassengerRestartDir /restart_files/bar
</VirtualHost>
<VirtualHost *:80>
ServerName www.baz.com
DocumentRoot /apps/baz/public
# A relative filename is given; Phusion Passenger will
# check for /apps/baz/restart_files/restart.txt
#
# Note that this directory is relative to the APPLICATION ROOT, *not*
# the value of DocumentRoot!
PassengerRestartDir restart_files
</VirtualHost>
-----------------------------------
.What are the security reasons for wanting to customize PassengerRestartDir?
Touching restart.txt will cause Phusion Passenger to restart the application.
So anybody who can touch restart.txt can effectively cause a Denial-of-Service
attack by touching restart.txt over and over. If your web server or one of your
web applications has the permission to touch restart.txt, and one of them has a
security flaw which allows an attacker to touch restart.txt, then that will
allow the attacker to cause a Denial-of-Service.
You can prevent this from happening by pointing PassengerRestartDir to a
directory that's readable by Apache, but only writable by administrators.
=== Resource control and optimization options ===
==== PassengerMaxPoolSize <integer> ====
The maximum number of Ruby on Rails or Rack 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/Rack 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 '6'.
TIP: We strongly recommend you to <<reducing_memory_usage,use Ruby Enterprise
Edition>>. This allows you to reduce the memory usage of your Ruby on Rails applications
by about 33%. And it's not hard to install.
==== PassengerMaxInstancesPerApp <integer> ====
The maximum number of application instances that may be simultaneously active
for a single application. This helps to make sure that a single application
will not occupy all available slots in the application pool.
This value must be less than <<PassengerMaxPoolSize,PassengerMaxPoolSize>>. A value of 0
means that there is no limit placed on the number of instances a single application
may use, i.e. only the global limit of <<PassengerMaxPoolSize,PassengerMaxPoolSize>>
will be enforced.
This option may only occur once, in the global server configuration.
The default value is '0'.
[[PassengerPoolIdleTime]]
==== PassengerPoolIdleTime <integer> ====
The maximum number of seconds that an application instance may be idle. That is,
if an application instance hasn't received any traffic after the given number of
seconds, then it will be shutdown in order to conserve memory.
Decreasing this value means that 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/Rack website. However, it will also
free up resources used by applications more quickly.
The optimal value depends on the average time that a visitor spends on a single