Lua API¶

Mode of operation¶

The Lua programs are located in /usr/lib/liveconfig/lua/ (respectively <library_path>/lua/ - see library_path), both with the LiveConfig server as well as the LiveConfig client (lcclient).

When LiveConfig starts, multiple threads for system management are started. Each of these threads contains its own Lua environment. Each Lua environment first loads its internal libraries (like LC.expect, LC.sys, and so on), then the main script liveconfig.lua is run. This loads all other Lua modules (LC.web, LC.dns etc.), all files in /etc/liveconfig/lua.d/*.lua and finally a file called custom.lua (if existing).

custom.lua¶

If you need to modify Lua functions, it is strongly recommended to not directly modify an existing Lua script, as this will be overwritten with the next LiveConfig update. Instead, create a file called custom.lua (at /usr/lib/liveconfig/lua or at /etc/liveconfig/lua.d/).

Testing own programs¶

For testing of custom Lua scripts you can use lclua (installed with LiveConfig, usually at /usr/lib/liveconfig/lclua). This Lua interpreter contains all Lua modules from LiveConfig.

Example code¶

For example, if you want to customize the detection of the Linux distribution, the custom.lua file might look like this:

-- introduce namespace "MY":
MY = { }

-- keep original function "LC.distribution.detect"
MY.orig_detect = LC.distribution.detect

-- redirect function for distribution detection:
function LC.distribution.detect()
  if (LC.fs.is_file("/etc/exampLinux")) then
    -- we have an "ExampleLinux"...
    LC.distribution.name        = "ExampLinux"
    LC.distribution.codename    = "example"
    LC.distribution.family      = "Debian"
    LC.distribution.version     = "1.0"
    LC.distribution.description = "Example Linux 1.0 (example)"
    return true
  else
    -- call original function for distribution detection:
    return MY.orig_detect()
  end
end

LiveConfig Lua Modules¶

The following modules are provided by LiveConfig: