Logging from an sbt plugin

Question

I use the s3 resolver plugin for sbt.

I have changed the credentials provider:

lazy val s3CredentialsProvider = {bucket: String =>
    new AWSCred         


        

Answer 1

This is a way of adding logging to classes that you defined for your AutoPlugin

import sbt._
import sbt.Keys._

object TestPlugin extends AutoPlugin {

  class SomeClassThatNeedsLogger(logger: Logger) {
    def doSomeLogging(): Unit = {
      logger.info("It logs")
    }
  }

  object autoImport {
    val someClassThatNeedsLoggerHolder = taskKey[SomeClassThatNeedsLogger]("Holds instance of SomeClassThatNeedsLogger")
    val runSomeClassThatNeedsLogger = taskKey[Unit]("Runs SomeClassThatNeedsLogger")
  }

  import autoImport._

  override def trigger = allRequirements

  override def projectSettings: Seq[Def.Setting[_]] = {
    Seq(
      someClassThatNeedsLoggerHolder := new SomeClassThatNeedsLogger(streams.value.log),
      runSomeClassThatNeedsLogger := someClassThatNeedsLoggerHolder.value.doSomeLogging()
    )
  }
}

And running gives us a log entry:

> runSomeClassThatNeedsLogger
[info] It logs
[success] Total time: 0 s, completed Feb 6, 2019 9:47:15 AM

Some notes on errors you're getting

value can only be called on a task within a task definition macro,
such as :=, +=, ++=, or Def.task.

This tells you that streams.value can be used only in task definitions like someClassThatNeedsLoggerHolder := new SomeClassThatNeedsLogger(streams.value.log)

ConsoleLogger using sbt.util.internal

As the package name suggests, this is an internal package and subject to a change in next versions of sbt. It should not be used in your plugin definitions.