krait

Configuration library for Kotlin, Java, and other JVM languages

Why?

Configuration in JVM world is weird. Usually we use unexpressive, but built-in -D command line option or .properties file, sometimes there is also some environment variables, rarely YAML, and more rarely you see some mix of two of them.

But people are different, and so are their projects, and sometimes you can encounter configuration in unexpected places, like database or hard-coded path in /opt or something like that.

So... What if you could use all configuration sources from one place? Like, single interface.

I work with configuration a lot, because I'm a DevOps engineer, and I wanted to made configuration access powerful both in my personal projects, and in services of my colleagaues.

Meet Krait, configuration library, inspired by Dynaconf:

// Given properties:
// app.key = test
// app.numbers.first = 1
// app.numbers.second = 2
// app.loggers.0.name = app
// app.loggers.0.level = info
// app.loggers.1.name = framework
// app.loggers.1.level = warn
// Given variables:
// APP__NUMBERS__THIRD = 3
// APP__LOGGERS__2__NAME = orm
// APP__LOGGERS__2__LEVEL = debug

// start with dev profile. some sources support loading different profiles,
// but EnvironmentSource and PropertiesSource doesn't.
val kr = Krait("dev") {
  sources {
    add(EnvironmentSource("APP")) // use environment variables, starting from 'APP'
    add(PropertiesSource("app")) // will be accessed in second order
  }
}
assertEquals("test", kr["key"].text())
assertEquals(123, kr["numbers"]["first"].long())
assertEquals(3, kr["numbers"].entries(String::class.java).size) // yay, merge of lists of different sources!
for (node in kr["loggers"].list()) {println(node["level"].text())} // will be three items, so same merge will happen for lists

More examples in tests. Documentation will be available soon. Or later.

I want to try it!

You can add Krait repo from CEC repo. Here's how to do it in Gradle Kotlin DSL:

repositories {
    maven { url = uri("https://maven.closeencounterscorps.org/releases") }
}
// ...
implementation("com.github.kam1sh.krait:krait-core:0.4.0") // core library, properties, environment and dotenv support
implementation("com.github.kam1sh.krait:krait-yaml:0.4.0") // YAML support

Naming

This library named after Krait MkII from Elite: Dangerous.