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Idofront-config lets you easily define a config using kotlinx.serialization, supporting yaml, json, and other formats automatically.

Define a serializable config class

class ExampleConfig(
    val cooldown: Int,
    val locations: List<String>,


Remember you can nest serializable classes to organize your config.

Define a config

Use the config builder to define a config during program startup. This will automatically build and read the config for you.

config<ExampleConfig>(fileName = "config") {
    // Extra config options go into the config block here


Notice, we did not specify a file type in our file name. Idofront will look for all supported file types until it finds a valid extension.

Define input source

Within our config block, we must specify one source for the file, here is a list of supported options:

  • fromPath(path: Path)
    Loads the config from a path without extension.
  • fromPluginPath(relativePath: Path, loadDefault: Boolean)
    Loads a config relative to the current plugin's config folder, if loadDefault is true, will also load from the jar's resources if no config file exists.
  • fromInputStream(getInputStream: (ext: String) -> InputStream?)
    Given an extension, loads arbitrary input.

Serialization options

Shared serializers module

Specifies a serializers module, shared across different config types.

serializersModule {
    // Start defining options like polymorphic serialization here


You may add or override config types by extension using the formats block. You should use the passed module if you want your config to use the shared module.

formats { module ->
    mapOf("yml" to Yaml(serializersModule = module, ...))


config<ExampleConfig>(fileName = "config") {
    fromPluginPath(loadDefault = true)

    serializersModule {
        polymorphic(SomeClass::class) {

This will load a file from the plugin config called config.<ext>. We can add a file: resources/config.yml in our project so that the loadDefault option will load it when a config file doesn't already exist.