app_lua Module

Daniel-Constantin Mierla

   asipto.com

Edited by

Daniel-Constantin Mierla

   <miconda@gmail.com>

   Copyright © 2010 Daniel-Constantin Mierla (asipto.com)
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. load (string)
              3.2. reload (boolean)
              3.3. log_mode (int)

        4. Functions

              4.1. lua_dofile(path)
              4.2. lua_dostring(script)
              4.3. lua_run(func [, params])
              4.4. lua_runstring(script)

        5. RPC Commands

              5.1. app_lua.list
              5.2. app_lua.reload
              5.3. app_lua.api_list

        6. Example of usage

   List of Examples

   1.1. Build against LuaJIT libraries
   1.2. Set load parameter
   1.3. Set reload parameter
   1.4. Set log_mode parameter
   1.5. lua_dofile usage
   1.6. lua_dostring usage
   1.7. lua_run usage
   1.8. lua_runstring usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. load (string)
        3.2. reload (boolean)
        3.3. log_mode (int)

   4. Functions

        4.1. lua_dofile(path)
        4.2. lua_dostring(script)
        4.3. lua_run(func [, params])
        4.4. lua_runstring(script)

   5. RPC Commands

        5.1. app_lua.list
        5.2. app_lua.reload
        5.3. app_lua.api_list

   6. Example of usage

1. Overview

   This module allows executing Lua scripts from config file, implementing
   the KEMI framework and exporting Lua module 'KSR'.

   To read more about KEMI exports and available KSR submodules, see:
     * https://kamailio.org/docs/tutorials/devel/kamailio-kemi-framework/

   Note: to have the old Lua module 'sr' available, load the 'app_lua_sr'
   Kamailio module.

   Lua (http://www.lua.org) is a fast and easy to embed scripting
   language. Exported API from SIP router to Lua is documented in the
   dokuwiki.

   The module has two Lua contexts:
     * first is used for functions lua_dofile() and lua_dostring().
     * second is used for function lua_run() and parameter 'load'.
       Therefore lua_run() cannot execute functions from scripts loaded
       via lua_dofile() in config. This is kind of caching mode, avoiding
       reading file every time, but you must be sure you do not have
       something that is executed by default and requires access to SIP
       message. This is also the context used with KEMI framework.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * none.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * liblua5.1-dev - Lua devel library. Versions 5.2, 5.3 and 5.4 also
       work.

   This module can be compiled against LuaJIT compiler (instead of
   standard Lua). Then this library is needed:
     * libluajit-5.1-dev - LuaJIT devel library.

   To enable that, LUAJIT variable has to be set.

   Example 1.1. Build against LuaJIT libraries
   E.g: $ LUAJIT="yes" make modules modules=modules/app_lua

   (Warning: LuaJIT version is 5.1, so scripts prepared for higher Lua
   versions may not work with LuaJIT)

3. Parameters

   3.1. load (string)
   3.2. reload (boolean)
   3.3. log_mode (int)

3.1. load (string)

   Set the path to the Lua script to be loaded at startup. Then you can
   use lua_run(function, params) to execute a function from the script at
   runtime. The script can be in Lua-source or bytecode.

   Default value is “null”.

   Example 1.2. Set load parameter
...
modparam("app_lua", "load", "/usr/local/etc/kamailio/lua/myscript.lua")
...

3.2. reload (boolean)

   If reload is 1 enables the ability to reload the scripts using the RPC
   app_lua.reload command. To disable reload feature, set this parameter
   to 0.

   Default value is “1 (on)”.

   Example 1.3. Set reload parameter
...
modparam("app_lua", "reload", 0)
...

3.3. log_mode (int)

   Control what is printed in log messages. If bit 1 is set, then the
   module prints debug messages for each KEMI export.

   Default value is “0”.

   Example 1.4. Set log_mode parameter
...
modparam("app_lua", "log_mode", 1)
...

4. Functions

   4.1. lua_dofile(path)
   4.2. lua_dostring(script)
   4.3. lua_run(func [, params])
   4.4. lua_runstring(script)

4.1.  lua_dofile(path)

   Execute the Lua script stored in 'path'. The parameter can be a string
   with pseudo-variables evaluated at runtime.

   Example 1.5. lua_dofile usage
...
lua_dofile("/usr/local/etc/kamailio/lua/myscript.lua");
...

4.2.  lua_dostring(script)

   Execute the Lua script stored in parameter. The parameter can be a
   string with pseudo-variables.

   Example 1.6. lua_dostring usage
...
if(!lua_dostring("KSR.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...

4.3.  lua_run(func [, params])

   Execute the Lua function 'func' giving 'params' as parameters. There
   can be up to 3 string parameters after 'func' (overall, max 4 params,
   first is the function). The function must exist in the Lua script
   loaded at startup via parameter 'load'. Parameters can be strings with
   pseudo-variables that are evaluated at runtime.

   Example 1.7. lua_run usage
...
if(!lua_run("sr_append_fu_to_reply")) {
    xdbg("SCRIPT: failed to execute lua function!\n");
}
...
lua_run("lua_func0");
lua_run("lua_func1", "$rU");
lua_run("lua_func2", "$rU", "2");
lua_run("lua_func3", "$rU", "2", "$si");
...

4.4.  lua_runstring(script)

   Execute the Lua script stored in parameter. The parameter can be a
   string with pseudo-variables. The script is executed in Lua context
   specific to loaded Lua files at startup.

   Example 1.8. lua_runstring usage
...
if(!lua_runstring("KSR.log([[err]], [[----------- Hello World from $fU\n]])"))
{
    xdbg("SCRIPT: failed to execute lua script!\n");
}
...

5. RPC Commands

   5.1. app_lua.list
   5.2. app_lua.reload
   5.3. app_lua.api_list

5.1.  app_lua.list

   Lists the id and path for every script loaded by the load parameter.

   Name: app_lua.list

   Parameters: none

   Example:
...
    kamctl rpc app_lua.list
...

5.2.  app_lua.reload

   Marks the need to reload the selected script. The actual reload is done
   by every working process when the next call to lua_run function is
   executed. If no parameter is added all the scripts are selected to be
   reloaded.

   Name: app_lua.reload

   Parameters: id

   Example:
...
    kamctl rpc app_lua.reload 0
...

5.3.  app_lua.api_list

   Lists the exported KEMI functions that can be used inside Lua scripts.

   Name: app_lua.api_list

   Parameters: none

   Example:
...
    kamctl rpc app_lua.api_list
...

6. Example of usage

   Create your Lua script and stored on file system, say:
   '/usr/local/etc/kamailio/lua/myscript.lua'.
...
function sr_append_fu_to_reply()
        KSR.hdr.append_to_reply("P-From: " .. KSR.pv.get("$fu") .. "\r\n");
end
...

   Load the script via parameter 'load' and execute function via
   lua_run(...).
...
modparam("app_lua", "load", "/usr/local/etc/kamailio/lua/myscript.lua")
...
route {
    ...
    if(!lua_run("sr_append_fu_to_reply"))
    {
        xdbg("SCRIPT: failed to execute lua function!\n");
    }
    ...
}
...
