How To Install HSC's mod_gzip
Program Location: Hyperspace
Date Written: June 10, 2001
Written By: Jason Rabel
What is mod_gzip?:
To be short and to the point, mod_gzip is an add-in that can
compress both STATIC and DYNAMIC web page output on the fly. Basically the
request comes in for a web page, then right before it is sent mod_gzip
compresses it, it gets sent over the internet compressed, then the clients web
browser automatically decompresses and displays it, it's totally transparent! If
you run on manage a web site, then definitely read on, this could be the article
Mod_gzip doesn't require any software to be installed on the
client side, all that is needed is a HTTP 1.1 compliant web browser which is
basically any browser released since early 1999. Even if a user doesn't have a
HTTP 1.1 compliant browser, they can still surf your site, mod_gzip just won't
compress the pages for them and for all purposes your web site functions just
like any other.
Mod_gzip runs on Apache web server for both linux & win32
platforms (and I'm sure you can run it on other *nix platforms as well). It will
compress all HTML, PHP, ColdFusion, Perl, Zope, WebLogic, IBM's WebSphere Server
Output, EXE, compiled 'C', mod_perl, mod_php, etc.
The benefits of installing mod_gzip are twofold. Not only are
you saving bandwidth by sending out smaller files (that can be a lot of money
for high-traffic sites), but also your web pages load faster on the client side
since it doesn't take as long to download. The impact on the web server itself
is minimal, and in some cases the cpu load is actually reduced from using this
Best of all, mod_gzip is free!
To install mod_gzip you must have root access to your system (or
Administrator if you are a Windows machine). With that said, I'm going to assume
that you have pretty good knowledge on how to use a text editor, restart your
web server, etc... So let's jump right in!
First you will need to download the mod_gzip file from Hyperspace
Comm's web site. I downloaded the pre-complied mod_gzip.so file since that
was the easiest and quickest way to get up and running. If you are a real
die-hard tweaking person you can always get the C source and re-compile it into
your Apache web server.
Next I put the mod_gzip.so file on my web server in the same
directory as my other modules, which is /usr/lib/apache. Then I set its permissions
to the same as the rest of the modules.
With that done, the next step is to edit the config file to have
it load the module with the proper settings. For most people this will be in the
httpd.conf (like me) or it could possibly be in the access.conf file. My conf
files are located in the /etc/httpd/conf directory, but yours may vary.
In the httpd.conf file look for the area where all the other
modules load. After the last module, add the line:
LoadModule gzip_module modules/mod_gzip.so
Then in some spot below, add the following lines. This is taken
from my config, you can tweak it to suit your needs.
# [ mod_gzip configuration ]
mod_gzip_item_include file \.htm$
mod_gzip_item_include file \.html$
mod_gzip_item_include file \.php$
mod_gzip_item_include file \.pl$
mod_gzip_item_include file \.cgi$
mod_gzip_item_include mime text/.*
If you want to learn more about what these commands are, there
is some extensive documentation on all the command HERE.
Basically my config lines tell mod_gzip to be used, compress any file over 300
bytes, the max in memory compression is 100,000 bytes, not to keep work files,
use /tmp for its temp area, and to dechunk files (needed for PHP4 &
ColdFusion). The includes basically tell it to compress all those files &
mime types, however you can also specify exclude statements. You can specify
either by file, mime, or handler.
Once you have those two bits in place, you can restart your web
server and mod_gzip should be running. However there are a couple things you can
add in your config file so you can make sure it is running and to see what kind
of compression you are getting.
One useful module is mod_info, you can use a couple commands and
the web server will return all sorts of info. If you don't have mod_info
installed already, you might have to download it if it's not in your modules
directory, but if it is there, then just add this line to the end of your
modules section in the config file:
LoadModule info_module modules/mod_info.so
Now you can enter the following commands in your web browser to
return a bunch of info and to find if mod_gzip is loaded (along with all the
other modules). The way my access.conf is set up, I had to add some lines to
allow my server-info and server-status to run, and I also have mine password
protected for safety measures. To run the server-info and server status, just
open your web browser and do the following:
If they don't show up then you are going to have to add the
location & handler info in your access.conf files (don't email me how, you
can look it up on the web or just look in your access.conf file, it is probably
already there but just commented out).
Next you can edit your httpd.conf and add in some extended log
info, which will show tell you if mod_gzip compressed the file, and by how much.
Here is the line below that I used, although you can tweak it how you want (more
info is at the Hyperspace Comm web site). I chose to keep it running separete
from my main log file since my stats program probably wouldn't like the extra
info. (It's needs to be all one line if you are going to copy & paste it)
LogFormat "%h %l %u %t \"%r\" %>s %b mod_gzip:
Then under the location where I specify my log stuff, I added
the following line. If you are running several web sites on your server, you
will need to add it to the virtual server that you want it to log. Also, you
might want to specify it where your other logs are just for simplicity sakes.
CustomLog /home/logs/mod_gzip.log full_plus_gzip
Once you have these lines in place, you can restart your web
server and it will start cranking out to the new log file. Here is an example
line from mine:
/reviews/cooling/HSR2_4.html HTTP/1.1" 200 6289 mod_gzip:
DECHUNK:OK In:23352 Out:6289:74pct.
As you can see, the original file was 23,352 bytes, but it
compressed it and sent only 6,289 bytes. That can really amount to a lot of
bandwidth savings! Once you get it running right, you might want to turn off
this log file (comment out the CustomLog line is the easiest) or at least do
something to rotate the log and compress the old one.
I know this is by no means thorough documentation on how to
install mod_gzip, but at least it should help point you in the right direction.
There really is no reason not to use this module, it save bandwidth, works even
with the most dynamic files, helps you page load faster on the client end, and
might even reduce your CPU load some. Hyperspace
Comm's web site is an excellent starting point, and they have several links
to other places with help and info. You can always install it with the bare
minimum (just putting the LoadModule line in) and always tweaking it to do more
after you are sure you have it running right.
I encourage other web sites running apache to try giving this
module a chance, your users will be thanking you for the faster load time on
pages that have lots of HTML (remember this program doesn't compress graphics,
simply because gzip can't compress an image smaller).
I even encourage the enthusiast at home who tinkers with their
Linux box to try installing it on their machine. You never know when in the
future you might use this.
Back To The Main Page