Automating Web Performance Best Practices with mod_pagespeed
Web performance is a brilliant, but sometimes complex world. Concatenating and minifying files, optimizing images, setting up caching, these are all tasks that can lead to great performance wins. We know that this stuff is good for performance but actually putting these strategies into practice can sometimes be tedious. A team at Google recognized this problem and came up with the idea of creating a web server module that would take of a whole bunch of performance optimizations for you; thus mod_pagespeed was born.
In this post you’re going to learn how to set up mod_pagespeed on an Apache web server. You’ll also be learning how to configure optimization filters that are provided by the module.
Note: This post assumes a familiarity with using the command line, SSH, and basic Apache configurations.
Performance Optimizations Covered by mod_pagespeed
The PageSpeed module (mod_pagespeed) contains a number of filters that are each responsible for taking care of an optimization task. By default, filters are enabled that handle:
- Image Optimization (Compression and Resizing)
- Asset Caching
As well as these common optimizations there are filters available for a wide range of other tasks, including:
- Removal of HTML Comments and Whitespace
- Lazy-loading Images (only loaded when they become visible in the viewport)
- Google Analytics Injection
- and more…
Later in this post you’ll learn how to enable these additional filters in the PageSpeed configuration.
Installing mod_pagespeed For Apache
In this post we’re going to focussing on setting up the PageSpeed module for an Apache web server. It’s worth noting that there is also an equivalent module available for nginx.
Note: In order to install the mod_pagespeed module you will need to have SSH access to your web server. If you use a shared hosting service this may not be the case, and therefore I’d advise you to contact your hosting provider and enquire if they have support for mod_pagespeed. You can also check to see if the module is enabled using a phpinfo file.
To install the mod_pagespeed module follow these steps.
1. Open a Connection to Your Server
Start by opening up Terminal and creating a new SSH connection to your server.
ssh user@hostname # e.g. ssh firstname.lastname@example.org
2. Download the Package
Download the appropriate package for your server environment. You can use the
wget program to save this file directly to your server.
wget <package url>
- 32 Bit (Debian/Ubuntu): https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_i386.deb
- 64 Bit (Debian/Ubuntu): https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_amd64.deb
- 32 Bit (CentOS/Fedora): https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_i386.rpm
- 64 Bit (CentOS/Fedora): https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_x86_64.rpm
3. Install the Package
Next you need to install the package. Instructions for doing this vary depending on what type of server you are using.
For Debian/Ubuntu servers:
sudo dpkg -i mod-pagespeed-*.deb sudo apt-get -f install
For CentOS/Fedora servers:
# only if 'at' is not installed sudo yum install at # install the package sudo rpm -U mod-pagespeed-*.rpm
4. Restart Apache
The mod_pagespeed module should now be installed on your server. All you need to do now is restart Apache.
service apache2 restart
The installation process should have enabled the new module for you. You can check this by looking for the
pagespeed.load files in the
/etc/apache2/mods-enabled directory. If these two files are present the module will be loaded by Apache and you’re good to go!
If you can’t find these
files in themods-enabled` folder, execute the following commands to enable the module and restart the web server.
cd /etc/apache2/mods-enabled ln -s ../mods-available/pagespeed.* ./ # Restart Apache service apache2 restart
Simply by installing mod_pagespeed you’ve bagged yourself a bunch of great performance wins. By default, mod_pagespeed will be enabled for all of the websites on your server.
The mod_pagespeed module comes with some of the most commonly used filters enabled by default. In this section you’re going to learn how to enable some of the other optimization filters that are provided.
The master configuration file for mod_pagespeed can be found at
/etc/apache2/mods-available/pagespeed.conf. This defines the global configuration for mod_pagespeed and therefore any changes that you make to this file will affect all of the websites on your server. This is great if you want all of your websites to use the same filters but there may be times when this is not the case.
If you’re using virtual hosts, an ideal place to put your site-specific PageSpeed filters is within the host configuration. Depending on your setup, you may find virtual hosts declared within the files in the
The snippet below shows an example
VirtualHost configuration with mod_pagespeed directives.
<VirtualHost *:80> DocumentRoot /www/example ServerName www.example.come # mod_pagespeed configuration ModPagespeedEnableFilters lazyload_images ModPagespeedDisableFilters inline_css </VirtualHost>
You can also use a
.htaccess file if you don’t have access to the configuration for you virtual host.
Note: By default, virtual hosts will inherit the options specified in the master
pagespeed.conf file. This behaviour is controlled using the
ModPagespeedInheritVHostConfig directive. Setting this to
off would cause each of the virtual hosts to have a completely independent PageSpeed configuration.
PageSpeed uses two different levels to make configuration simple. The
CoreFilters level enables a default set of filters that will make your website faster. You can then enable or disable filters to modify the configuration as you wish.
Alternatively you can disable
CoreFilters by setting the
PassThrough. You will then need to manually enable all of the filters that you wish to use.
Unless you have some very specific requirements it’s often best to leave the
CoreFilters and then modify the enabled filters in the host configuration.
To enable a filter you use the
You can find a full list of the different filters available here.
Note than some filters rely on additional configuration variables, such as the
insert_ga filter which will automatically insert the Google Analytics code into your pages.
ModPagespeedEnableFilters insert_ga ModPagespeedAnalyticsID <Analytics ID>
Refer to the documentation for each of the options to find out if you need to set additional variables.
To disable a filter you use the
Specifying this in your host config will override the options specified in
As well as disabling filters you can also forbid virtual hosts from using specific filters. This is done using the
Forbidding access to filters can be useful if you manage a server that hosts many different websites.
Disabling mod_pagespeed for a Website
You can disable the PageSpeed module completely for a specific website by setting
off in your host configuration.
If you only need to temporarily disable mod_pagespeed for testing purposes, you can just add the
ModPagespeed=off query parameter to the URL.
We all know that optimizing websites for performance is a big part of web development today, but taking care of all the different optimization tasks can often become tedious. The PageSpeed module you’ve learned about here takes care of much of this headache; leaving you to do what you do best – build great websites.
I highly recommend that you take a little time to install this module on your web servers. For a minimal amount of effort you can unlock a wide range of performance gains and supercharge your websites.
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