Sbt: How to define task for all projects? - scala

Question

I would like to be able to define a task for all projects in my sbt.build:
lazy val project1 = project.in(`.` / "project1)
...
lazy val project2 =
...
lazy val upload = taskKey[Unit]("upload a config file from project to server)
upload := {
val file = baseDirectory.value / "config.json"
...
}
The problem is this definition works only when I call sbt upload, but I would like to be able to call it for each subproject: sbt project1/upload and sbt project2/upload.
Is there a way to do it, without using inputKey?

Answer 1

See Organizing the build:
For more advanced users, another way of organizing your build is to define one-off auto plugins in project/*.scala. By defining triggered plugins, auto plugins can be used as a convenient way to inject custom tasks and commands across all subprojects.
project/UploadPlugin.scala
package something
import sbt._
import Keys._
object UploadPlugin extends AutoPlugin {
override def requires = sbt.plugins.JvmPlugin
override def trigger = allRequirements
object autoImport {
val upload = taskKey[Unit]("upload a config file from project to server")
}
import autoImport._
override lazy val projectSettings = Seq(
upload := {
val n = name.value
println(s"uploading $n..")
}
)
}
build.sbt
Here's how you can use it:
ThisBuild / organization := "com.example"
ThisBuild / scalaVersion := "2.12.5"
ThisBuild / version := "0.1.0-SNAPSHOT"
lazy val root = (project in file("."))
.aggregate(project1, project2)
.settings(
name := "Hello"
)
lazy val project1 = (project in file("project1"))
lazy val project2 = (project in file("project2"))
build.sbt does not have to mention anything about UploadPlugin, since it's a triggered plugin. From the shell you can call:
sbt:Hello> project1/upload
uploading project1..
[success] Total time: 0 s, completed Jul 20, 2018
sbt:Hello> project2/upload
uploading project2..
[success] Total time: 0 s, completed Jul 20, 2018

Answer 2

You can add the task as a setting of the project you want :
lazy val uploadTask = {
lazy val upload = taskKey[Unit]("upload a config file from project to server)
upload := {
val file = baseDirectory.value / "config.json"
...
}
}
project.in(`.` / "project1).settings(uploadTask)