How to use "Customize Run Instances..."

Customize Run Instances

Note

General Godot 4 knowledge which can be useful for any project.

This Godot 4 feature allows you to run multiple different instances of the project at once, and the most interesting aspect is that you can set specific launch arguments and feature tags for each instance.

It can be helpful for various purposes, but for multiplayer projects, it’s especially useful to run a server and multiple clients at once from the same Godot editor in one click.

In a small-scale project, we can simply use two feature tags to determine whether an instance should start as a client or a server.

Here’s a simple example in the "Run Instances" window, which you can access at Debug → Customize Run Instances...:

And how it could be used in code:

func _ready() -> void:
	if OS.has_feature("client"):
		start_as_client()
	elif OS.has_feature("server"):
		start_as_server()

Use Multiple Instances in Godot Tiny MMO

Feature Tags

In Godot Tiny MMO, we use feature tags to decide if the project is a world server, gateway server, master server, or client.

The tags for this project are:

• client
• gateway-server
• master-server
• world-server

These tags are used in source/common/main.gd as follows:

func _ready() -> void:
	if OS.has_feature("client"):
		start_as_client()
	elif OS.has_feature("world-server"):
		start_as_world_server()
	elif OS.has_feature("gateway-server"):
		start_as_gateway_server()
	elif OS.has_feature("master-server"):
		start_as_master_server()

func start_as_client() -> void:
	get_tree().change_scene_to_file.call_deferred("res://source/client/client_main.tscn")
...

Launch Arguments

We also use these launch arguments:

• --headless: Runs the project without window and audio.
  Enabling headless mode is equivalent to --display-driver headless --audio-driver Dummy.
• --config: Specifies a custom config path.
  Usage example: --config="config/gateway_config.cfg"
  Config files are used to set networking information, such as certificate paths, ports, and addresses.
  Default configuration files are located in test_config/.

Example gateway_config.cfg file:

; Example of gateway_config.cfg file.
[gateway-server]
port=8088
certificate_path="res://test_config/tls/certificate.crt"
key_path="res://test_config/tls/key.key"

[gateway-manager-client]
port=8064
address="127.0.0.1"
certificate_path="res://test_config/tls/certificate.crt"

Here’s an example of how to use this feature in Godot Tiny MMO:

Links

• Official documentation on the "Customize Run Instances..." feature.
• Official documentation on general command line references and launch argument options.