mod_macro
Provides macros within apache httpd runtime configuration files
Base
mod_macro.c
macro_module
Available in httpd 2.4.5 and later

Provides macros within Apache httpd runtime configuration files, to ease the process of creating numerous similar configuration blocks. When the server starts up, the macros are expanded using the provided parameters, and the result is processed as along with the rest of the configuration file.

# Usage

Macros are defined using Macro blocks, which contain the portion of your configuration that needs to be repeated, complete with variables for those parts that will need to be substituted.

For example, you might use a macro to define a VirtualHost block, in order to define multiple similar virtual hosts:

<Macro VHost $name $domain> <VirtualHost *:80> ServerName $domain ServerAlias www.$domain

DocumentRoot "/var/www/vhosts/$name" ErrorLog "/var/log/httpd/$name.error_log" CustomLog "/var/log/httpd/$name.access_log" combined </VirtualHost> </Macro>

Macro names are case-insensitive, like httpd configuration directives. However, variable names are case sensitive.

You would then invoke this macro several times to create virtual hosts:

Use VHost example example.com Use VHost myhost hostname.org Use VHost apache apache.org

UndefMacro VHost

At server startup time, each of these Use invocations would be expanded into a full virtualhost, as described by the Macro definition.

The UndefMacro directive is used so that later macros using the same variable names don't result in conflicting definitions.

A more elaborate version of this example may be seen below in the Examples section.

# Tips

Parameter names should begin with a sigil such as `$`, `%`, or `@`, so that they are clearly identifiable, and also in order to help deal with interactions with other directives, such as the core Define directive. Failure to do so will result in a warning. Nevertheless, you are encouraged to have a good knowledge of your entire server configuration in order to avoid reusing the same variables in different scopes, which can cause confusion.

Parameters prefixed with either `$` or `%` are not escaped. Parameters prefixes with `@` are escaped in quotes.

Avoid using a parameter which contains another parameter as a prefix, (For example, `$win` and `$winter`) as this may cause confusion at expression evaluation time. In the event of such confusion, the longest possible parameter name is used.

If you want to use a value within another string, it is useful to surround the parameter in braces, to avoid confusion:

<Macro DocRoot ${docroot}> DocumentRoot "/var/www/${docroot}/htdocs" </Macro>

# Examples

## Virtual Host Definition

A common usage of mod_macro is for the creation of dynamically-generated virtual hosts.

## Define a VHost Macro for repetitive configurations

<Macro VHost $host $port $dir> Listen $port <VirtualHost *:$port>

ServerName $host DocumentRoot "$dir"

# Public document root <Directory "$dir"> Require all granted </Directory>

# limit access to intranet subdir. <Directory "$dir/intranet"> Require ip 10.0.0.0/8 </Directory> </VirtualHost> </Macro>

## Use of VHost with different arguments.

Use VHost www.apache.org 80 /vhosts/apache/htdocs Use VHost example.org 8080 /vhosts/example/htdocs Use VHost www.example.fr 1234 /vhosts/example.fr/htdocs

## Removal of a macro definition

It's recommended that you undefine a macro once you've used it. This avoids confusion in a complex configuration file where there may be conflicts in variable names.

<Macro DirGroup $dir $group> <Directory "$dir"> Require group $group </Directory> </Macro>

Use DirGroup /www/apache/private private Use DirGroup /www/apache/server admin

UndefMacro DirGroup
Macro
Define a configuration file macro
<Macro name [par1 .. parN]> ... </Macro>
server config
virtual host
directory

The Macro directive controls the definition of a macro within the server runtime configuration files. The first argument is the name of the macro. Other arguments are parameters to the macro. It is good practice to prefix parameter names with any of '`$%@`', and not macro names with such characters.

<Macro LocalAccessPolicy> Require ip 10.2.16.0/24 </Macro>

<Macro RestrictedAccessPolicy $ipnumbers> Require ip $ipnumbers </Macro>
Use
Use a macro
Use name [value1 ... valueN]
server config
virtual host
directory

The Use directive controls the use of a macro. The specified macro is expanded. It must be given the same number of arguments as in the macro definition. The provided values are associated to their corresponding initial parameters and are substituted before processing.

Use LocalAccessPolicy ... Use RestrictedAccessPolicy "192.54.172.0/24 192.54.148.0/24"

is equivalent, with the macros defined above, to:

Require ip 10.2.16.0/24 ... Require ip 192.54.172.0/24 192.54.148.0/24
UndefMacro
Undefine a macro
UndefMacro name
server config
virtual host
directory

The UndefMacro directive undefines a macro which has been defined before hand.

UndefMacro LocalAccessPolicy UndefMacro RestrictedAccessPolicy