Dynamic Module Loading Support (DSO)

Description

  • You can choose which functionalities to include by selecting a set of modules. A module will be compiled as a Dynamic Shared Object (DSO) that exists from the main tengine binary. So you don't have to recompile tengine when you want to add or enable a functionality to it.

  • If you want to enable a standard module, you can enable it via configure's option while compiling tengine, for instance, --with-http_example_module or --with-http_examplemodule=shared. Run./configure --help_ for more details.

  • The maximum of dynamically loaded modules is limited to 128.

  • For now, only HTTP modules can be dynamically loaded.

  • This feature is tested only on Linux/FreeBSD/MacOS.

Example

worker_processes 1;
dso {
load ngx_http_lua_module.so;
load ngx_http_memcached_module.so;
}
events {
worker_connections 1024;
}

Directives

Syntax: path path
Default: _NGXPREFIX/modules
Context: dso

This directive specifies the default path (prefix) of DSO modules.

Example:

path /home/dso/module/;

Sets the default path to _/home/dso/module/.


Syntax: _load [module_name] [modulepath]
Default: none
Context: dso

The load directive loads the shared object file and enables the module. _modulename is the name of the DSO module, and _modulepath is the path of the DSO module.

The order in which the module is searched is as follows:

  • the absolute path.
  • relative path to the prefix specified by the 'path' directive.
  • relative path to the default path (NGX_PREFIX/modules or path which is specified by the '--dso-path' configure option).

Example:

load ngx_http_empty_gif_module ngx_http_empty_gif_module.so;
load ngx_http_test_module;
load ngx_http_test2_module.so;

It will load the ngx_http_empty_gif_module from ngx_http_empty_gif_module.so, ngx_http_test_module and ngx_http_test2_module from ngx_http_test_module.so and ngx_http_test2_module.so.


Syntax: _module_stub modulename
Default: none
Context: dso

This directive can insert a module into nginx's module array in order (see conf/module_stubs for more details). Note it will change the module runtime order. This directive does not need to be used in most cases. Don't use it or edit the _conf/modulestubs file unless you know what you are doing.

Example:

module_stub ngx_core_module;
module_stub ngx_errlog_module;
module_stub ngx_conf_module;
module_stub ngx_events_module;
module_stub ngx_event_core_module;
module_stub ngx_epoll_module;
module_stub ngx_openssl_module;
module_stub ngx_http_module;
module_stub ngx_http_core_module;
.......................
module_stub ngx_http_addition_filter_module;
module_stub ngx_http_my_filter_module;

It will place ngx_http_my_filter_module before ngx_http_addition_filter_module.


Syntax: _include filename
Default: none
Context: dso

Specifies a file which contains the module stubs (via the module_stub directive).

Example:

include module_stubs;

It will load conf/module_stubs and define the loading order of the modules (via the module_stub directive).

How to compile a module

If you want to enable a standard module after you compiled and installed tengine, you can take these steps as following.

  • enable the standard module you wanted in shared mode, for ### example:

    $ ./configure --with-http_sub_module=shared
  • compile it:

    $ make
  • install the shared object (*.so):

    $ make dso_install

It will copy the *.so files to the destination, or you can copy the files you want (in objs/modules) manually to the modules directory.

You can use the dso_tool located in the directory of nginx binary to compile a third party module.

Example:

./dso_tool --add-module=/home/dso/lua-nginx-module

It will compile the ngx_lua module into a shared object, and install it to the default module path. You can specify the destination directory you want install to by the --dst option.