Apache HTTP Server Version 2.0
apxs
is a tool for building and installing extension modules for the Apache HyperText Transfer Protocol (HTTP) server. This is achieved by building a dynamic shared object (DSO) from one or more source or object files which then can be loaded into the Apache server under runtime via the LoadModule
directive from mod_so
.
So to use this extension mechanism your platform has to support the DSO feature and your Apache httpd
binary has to be built with the mod_so
module. The apxs
tool automatically complains if this is not the case. You can check this yourself by manually running the command
$ httpd -l
The module mod_so
should be part of the displayed list. If these requirements are fulfilled you can easily extend your Apache server's functionality by installing your own modules with the DSO mechanism by the help of this apxs
tool:
$ apxs -i -a -c mod_foo.c
gcc -fpic -DSHARED_MODULE -I/path/to/apache/include -c mod_foo.c
ld -Bshareable -o mod_foo.so mod_foo.o
cp mod_foo.so /path/to/apache/modules/mod_foo.so
chmod 755 /path/to/apache/modules/mod_foo.so
[activating module `foo' in /path/to/apache/etc/httpd.conf]
$ apachectl restart
/path/to/apache/sbin/apachectl restart: httpd not running, trying to start
[Tue Mar 31 11:27:55 1998] [debug] mod_so.c(303): loaded module foo_module
/path/to/apache/sbin/apachectl restart: httpd started
$ _
The arguments files can be any C source file (.c), a object file (.o) or even a library archive (.a). The apxs
tool automatically recognizes these extensions and automatically used the C source files for compilation while just using the object and archive files for the linking phase. But when using such pre-compiled objects make sure they are compiled for position independent code (PIC) to be able to use them for a dynamically loaded shared object. For instance with GCC you always just have to use -fpic
. For other C compilers consult its manual page or at watch for the flags apxs
uses to compile the object files.
For more details about DSO support in Apache read the documentation of mod_so
or perhaps even read the src/modules/standard/mod_so.c
source file.
apxs -g [ -S name=value ] -n modname
apxs -q [ -S name=value ] query ...
apxs -c [ -S name=value ] [ -o dsofile ] [ -I incdir ] [ -D name=value ] [ -L libdir ] [ -l libname ] [ -Wc,compiler-flags ] [ -Wl,linker-flags ] files ...
apxs -i [ -S name=value ] [ -n modname ] [ -a ] [ -A ] dso-file ...
apxs -e [ -S name=value ] [ -n modname ] [ -a ] [ -A ] dso-file ...
-n modname
-i
(install) and -g
(template generation) option. Use this to explicitly specify the module name. For option -g
this is required, for option -i
the apxs
tool tries to determine the name from the source or (as a fallback) at least by guessing it from the filename.-q
apxs
's knowledge about certain settings. The query parameters can be one or more of the following strings: CC
, CFLAGS
, CFLAGS_SHLIB
, INCLUDEDIR
, LD_SHLIB
, LDFLAGS_SHLIB
, LIBEXECDIR
, LIBS_SHLIB
, SBINDIR
, SYSCONFDIR
, TARGET
.
Use this for manually determining settings. For instance use
INC=-I`apxs -q INCLUDEDIR`
inside your own Makefiles if you need manual access to Apache's C header files.
-S name=value
-g
-n
) and there two files: A sample module source file named mod_name.c
which can be used as a template for creating your own modules or as a quick start for playing with the apxs mechanism. And a corresponding Makefile
for even easier build and installing of this module.-c
-o
option is specified the output file is guessed from the first filename in files and thus usually defaults to mod_name.so
.-o dsofile
mod_unknown.so
is used.-D name=value
-I incdir
-L libdir
-l libname
-Wc,compiler-flags
-Wl,linker-flags
-i
-a
LoadModule
line to Apache's httpd.conf
configuration file, or by enabling it if it already exists.-A
-a
but the created LoadModule
directive is prefixed with a hash sign (#
), i.e., the module is just prepared for later activation but initially disabled.-e
-a
and -A
options similarly to the -i
operation to edit Apache's httpd.conf
configuration file without attempting to install the module.Assume you have an Apache module named mod_foo.c
available which should extend Apache's server functionality. To accomplish this you first have to compile the C source into a shared object suitable for loading into the Apache server under runtime via the following command:
$ apxs -c mod_foo.c
gcc -fpic -DSHARED_MODULE -I/path/to/apache/include -c mod_foo.c
ld -Bshareable -o mod_foo.so mod_foo.o
$ _
Then you have to update the Apache configuration by making sure a LoadModule
directive is present to load this shared object. To simplify this step apxs
provides an automatic way to install the shared object in its "modules" directory and updating the httpd.conf
file accordingly. This can be achieved by running:
$ apxs -i -a mod_foo.c
cp mod_foo.so /path/to/apache/modules/mod_foo.so
chmod 755 /path/to/apache/modules/mod_foo.so
[activating module `foo' in /path/to/apache/etc/httpd.conf]
$ _
This way a line named
LoadModule foo_module modules/mod_foo.so
is added to the configuration file if still not present. If you want to have this disabled per default use the -A
option, i.e.
$ apxs -i -A mod_foo.c
For a quick test of the apxs mechanism you can create a sample Apache module template plus a corresponding Makefile via:
$ apxs -g -n foo
Creating [DIR] foo
Creating [FILE] foo/Makefile
Creating [FILE] foo/mod_foo.c
$ _
Then you can immediately compile this sample module into a shared object and load it into the Apache server:
$ cd foo
$ make all reload
apxs -c mod_foo.c
gcc -fpic -DSHARED_MODULE -I/path/to/apache/include -c mod_foo.c
ld -Bshareable -o mod_foo.so mod_foo.o
apxs -i -a -n "foo" mod_foo.so
cp mod_foo.so /path/to/apache/modules/mod_foo.so
chmod 755 /path/to/apache/modules/mod_foo.so
[activating module `foo' in /path/to/apache/etc/httpd.conf]
apachectl restart
/path/to/apache/sbin/apachectl restart: httpd not running, trying to start
[Tue Mar 31 11:27:55 1998] [debug] mod_so.c(303): loaded module foo_module
/path/to/apache/sbin/apachectl restart: httpd started
$ _
You can even use apxs
to compile complex modules outside the Apache source tree, like PHP3:
$ cd php3
$ ./configure --with-shared-apache=../apache-1.3
$ apxs -c -o libphp3.so mod_php3.c libmodphp3-so.a
gcc -fpic -DSHARED_MODULE -I/tmp/apache/include -c mod_php3.c
ld -Bshareable -o libphp3.so mod_php3.o libmodphp3-so.a
$ _
because apxs
automatically recognized C source files and object files. Only C source files are compiled while remaining object files are used for the linking phase.