Since Apache 1.3 supports DSOs, you can easily load Apache modules or
compile in your own modules to your Web server. DSO support means that
modules may be loaded at runtime. Since the modules are only loaded as
necessary, they will not use any memory unless they are loaded and less
memory will be needed overall.
The Apache Group provides complete DSO Documentation at http://httpd.apache.org/docs/dso.html. After
installation of your server, you can also check
http://your_domain/manual/mod/ for
documentation on Apache modules in HTML format (if you installed the
apache-manual package). A short description of how
to load modules is provided next. If you need more details, check the
URLs provided.
For Apache to use a dynamically shared module, that module must have a
LoadModule line and an AddModule
line in httpd.conf. By default, many modules have
these two lines already included in httpd.conf, but
a few of the less commonly used modules are commented out. The
commented out modules were included during compilation, but they are not
loaded by default.
If you need to use one of those non-loaded modules, look in the
httpd.conf file to see all the available modules.
Each of the available modules has a corresponding
LoadModule line. To show you an example, the
LoadModule section begins with these seven lines:
#LoadModule mmap_static_module modules/mod_mmap_static.so
LoadModule vhost_alias_module modules/mod_vhost_alias.so
LoadModule env_module modules/mod_env.so
LoadModule config_log_module modules/mod_log_config.so
LoadModule agent_log_module modules/mod_log_agent.so
LoadModule referer_log_module modules/mod_log_referer.so
#LoadModule mime_magic_module modules/mod_mime_magic.so |
Most of the lines are not commented out, indicating that each associated
module was compiled in and is loaded in by default. The first line is
commented out, which means that the corresponding module
(mmap_static_module) was compiled in but not loaded.
To make Apache load an unloaded module, first uncomment the
corresponding LoadModule line. For example, if you
wanted to make Apache load in the mime_magic_module,
uncomment this line:
#LoadModule mime_magic_module modules/mod_mime_magic.so |
Next, you need to uncomment the corresponding line from the
AddModule section in httpd.conf.
To continue with our previous example, uncomment the
mod_mime_magic line, which looks like the following:
#AddModule mod_mime_magic.c |
Once you have uncommented the LoadModule and
AddModule lines for the module that you want to load
in, stop and start Apache, as covered in the section called Starting and Stopping httpd. After starting, the module
should be loaded in to Apache.
If you have your own module, you can add it to the
httpd.conf file so that it is compiled in and
loaded as a DSO. If you want to do this, you need to install the
apache-devel package, as covered in Chapter 13. You need the
apache-devel package because it installs the
include files, the header files and the APache eXtenSion (APXS) support
tool. APXS uses the include files and the header files to compile your
module so that it will work with Apache.
 | Warning |
|---|
| | If you plan to use the Apache Configuration
Tool, a GUI utility provided with Red Hat Linux, you must not
compile your own modules to your Apache Web server or edit your
Apache Web server's httpd.conf configuration
file. Conversely, if you want to add modules to Apache or edit
httpd.conf by hand, do not use the
Apache Configuration Tool.
If you need more information on the Apache Configuration
Tool, please see the Official Red Hat Linux Customization Guide.
|
If you have written your own module or are borrowing someone else's, you
should be able to use APXS to compile your module sources outside the
Apache source tree, without needing to tweak any compiler and/or linker
flags. If you need more information on APXS, please see the Apache
documentation at http://httpd.apache.org/docs/dso.html.
Once you have compiled your module using APXS, put your module into
/usr/lib/apache. Then your module needs both a
LoadModule line and an AddModule
line in the httpd.conf file, just as described
previously for Apache's own modules. After the
LoadModule list in httpd.conf,
add a line for the shared object file for your module like the
following:
LoadModule foo_module modules/mod_foo.so |
Note that you will need to change the name of the module and the name of
your shared object file as appropriate.
At the end of the AddModule list in
httpd.conf, add a line for the source code file for
your module like the following:
Note that you will need to change the name of the source code file as
appropriate.
Once you have completed the previous steps, stop and start your Web
server as outlined in the section called Starting and Stopping httpd. If
you have done everything correctly and your module is correctly coded,
your Web server should find your module and load it in as it starts.
The mod_ssl security portion of the Web server is provided as a Dynamic
Shared Object (DSO). This means that the Apache Web server can be
re-compiled by users if the EAPI extension patch from the mod_ssl
security module is applied to Apache. Follow the instructions for
building mod_ssl into Apache included with the mod_ssl documentation,
but add the following flag:
The complete command line should look like the following:
./configure [userflags] --with-eapi-only |
Then build and install Apache.
 | Note |
|---|
| | Red Hat cannot support re-compiled versions of the Apache Web server.
Installation of the shipped version is supported, but if you
re-compile Apache, you are on your own. Please do not re-compile
Apache unless you know exactly what you are doing.
|
