How to run sbt tasks with custom settings

Wed, 01 Oct 2025 00:00:00 +0000

When preparing build configuration in sbt, you might want to write custom sbt task. Task in sbt is like a function that can depend on other tasks and project settings.

Custom sbt tasks

To illustrate it, let’s write a simple task that validates environment, runs tests and builds an app

import sbt.*

lazy val validateAndBuild = taskKey[Unit]("Validates env, runs tests and builds the app")

val root = project.in(file(".")).settings(
  validateAndBuild := {
    validateEnvVars
    test
    assembly
  }
)

Tasks vs immutable settings

This can be handy when the project grows in complexity. One problem with this approach is that we don’t control the inputs to the sub-tasks that we run. In sbt, settings are initialized when the project is loaded and are not mutable.

Sbt on Dev notes

How to run sbt tasks with custom settings

Custom sbt tasks

Tasks vs immutable settings