factorio-clusterio/docs/developing-for-clusterio.md

Developing for Clusterio

This document describes the various different types of content that can be created for Factorio and/or Clusterio and how this is made compatible with Clusterio.

Contents

• Factorio Mods
• Factorio Scenarios
  • event_handler interface
• Communicating between Clusterio and Factorio
• Communicating with Clusterio
• Clusterio Modules
• Clusterio Plugins

Factorio Mods

Factorio mods that do not interact with Clusterio should not have any conciderations that need to be taken into account for them to work with Clusterio.

Factorio Scenarios

Clusterio patches saves and because of this scenarios have a few limitations and must explicitly mark themselves as compatible with Clusterio to work. The main limitation is that the event_handler lib must be used, and control.lua cannot contain any code other than calls to event_handler loading the relevant libs of the scenario. This is because the control.lua file will be overwritten by the save patcher. Scenarios also cannot use the event registring functions exposed by script such as script.on_event or script.on_nth_tick as using these will overwrite the handlers registered by the event_handler lib.

A breif description of the usage of the event_handler library is provided in the event_handler interface section.

Once a scenario is made using the event_handler it should have a control.lua file that looks something like this:

-- control.lua
local event_handler = require("event_handler")
event_handler.add_lib(require("module_foo"))
event_handler.add_lib(require("module_bar"))

To make Clusterio recognize and correctly handle this scenario it needs to include a clusterio.json file with following content:

{
    "scenario": {
        "name": "example-scenario",
        "modules": [
            "module_foo",
            "module_bar"
        ]
    }
}

This tells Clusterio that it should load both module_foo and module_bar by passing the result of requiring them to the add_lib function when writing a new control.lua file to the save.

event_handler interface

_{Note: At the time of writing the event_handler lib has been a part of Factorio since at least 0.17.4, and was moved from base to core in 0.17.63 but is still not documented anywhere. A brief description is provided here for this reason.}

The event_handler lib provides a simple interface for registring multiple callbacks to the same events without having to be concerned with callback chaining or overwriting callbacks defined elsewhere. It works by taking over the task of registring the actual callbacks with Factorio, providing its own interface for the rest of the code to use.

The sole function of interest exported by event_handler is add_lib which accepts a table with event handler callbacks definitions that it will register. The following entries are recognized by add_lib, all of which are optional:

• on_init: Callback called when the callback of script.on_init is invoked.
• on_load: Callback called when the callback of script.on_load is invoked.
• on_configuration_changed: Callback called when the callback of script.on_configuration_changed is invoked.
• events: Table mapping event ids as defined in defines.events to callbacks. For example the table { [defines.events.on_player_died] = foo } will call bar with the usual event table as argument every time a player dies.
• on_nth_tick: Table mapping the nth tick number to a callback. For example the table { [30] = bar } will call bar every 30th tick.
• add_remote_interface: Callback called before on_init/on_load callbacks^[1]. It has no special meaning and receives no arguments but should be used for registring remote interfaces.
• add_commands: Callback called before on_init/on_load callbacks^[1]. It has no special meaning and receives no arguments but should be used for registring commands.

_{1: Before 0.17.69 these callbacks were called after on_init/on_load.}

The usual way to use add_lib is to define the table of events to register in a separate file and return it, then load it in control.lua via require before passing it to add_lib. For example a module could be defined as

-- example.lua
local function my_handler(event)
    local name = game.player[event.player_index].name
    game.print("It appears that " .. name .. " has died")
end

return {
    on_init = function() game.print("example_lib init") end,
    events = {
        [defines.events.on_player_died] = my_handler,
    },
}

And then in control.lua the following used to load it with add_lib:

-- control.lua
local event_handler = require("event_handler")
event_handler.add_lib(require("example"))

Because the event_handler lib registers events itself you may not use script.on_load or script.on_init at all in your code and any usage of script.on_configuration_changed, script.on_nth_tick and/or script.on_event will cause the corresponding events registered with event_handler to break and should therefore not be used.

There's also the add_libraries function exported by event_handler, which accepts a table and calls add_lib for each value in the table.

Communicating between Clusterio and Factorio

There is currently no standard interface for moving data between Clusterio and Factorio. It's mostly a mix of RCON commands initiated from Clusterio plugins and writing out files with game.write_file that is picked up and parsed by plugins.

Communicating with Clusterio

There's a poorly to virtuarly undocumented HTTP interface that can be used to communicate with Clusterio to do things like get the status of instances, grab items from the store, run commands on instances, etc, etc. For now you can read the source code, and maybe ask on the Discord for some pointers if you get stuck.

Clusterio Modules

Modules are primarily used by plugins to inject code into Factorio games with the save patcher. The save patcher puts modules into the modules folder of the Factorio save and adds code to control.lua to load the modules by requiring it and passing the result of the require call to the add_lib function of the event_handler lib. See the section on the event_handler interface for a detailed description on how this works.

Because modules can be patched into an existing game you cannot rely on the on_init callback to be called in Clusterio Modules. Nor can you rely on the on_configuration_changed callback, as this is not called when level code changes. Instead you will have to initialize whatever global variable you need when you first use them.

Currently any files in a folder named lua in a Clusterio plugin is assumed to be a module and will be patched into the save before starting up Factorio. This will most likely change with the planned plugin restructuring.

Clusterio Plugins

The plugin interface is undergoing a major rewrite, and will be documented once that is done. See issue #220 for details.