Multiple main classes with SBT assembly - scala

I'm looking to create jars for AWS Lambda to run job tasks. Currently my build.sbt file looks something like this:
lazy val commonSettings = Seq(...)
lazy val core = project
.settings(commonSettings: _*)
lazy val job = project
.settings(commonSettings: _*)
.dependsOn(core)
lazy val service = project
.settings(commonSettings: _*)
.settings(
mainClass in assembly := Some("io.example.service.Lambda"),
assemblyJarName in assembly := "lambda.jar"
)
.dependsOn(core)
Running sbt assembly assembles the service module into a jar for my API and that works fine. The module job however will have multiple Main classes (one pr. job) and when I run sbt assembly job the service module is also assembled (even through its not depended on).
How can I configure my setup to only assemble the job module when needed, and specify individual mainClasses as separately assembled jars?

Set mainClass in assembly in job to define which main class to use, and run job/assembly to just assemble the job assembly jar.

You will need to override the default main class at build time by setting the property explicitly.
sbt "; set mainClass in assembly := Some("another/class"); job/assembly"
Not sure it's good practice but alternatively you can define a sub-project for each job with the correct main class set.
lazy val job1 = project
.settings(commonSettings: _*)
.settings(
mainClass in assembly := Some("io.example.service.Lambda"),
assemblyJarName in assembly := "lambda.jar"
)
.dependsOn(core)
lazy val job2 = project
.settings(commonSettings: _*)
.settings(
mainClass in assembly := Some("io.example.service.Lambda2"),
assemblyJarName in assembly := "lambda2.jar"
)
.dependsOn(core)

Related

Sbt generated docker container fails to package subproject

I have a multi-project build.sbt file, with projects like so:
lazy val utils = (project in file("utils"))
.settings(
Seq(
publishArtifact := false
)).[...]
lazy val api = (project in file("api"))
.dependsOn(utils)
.settings(commonSettings: _*)
.enablePlugins(JavaAppPackaging, DockerPlugin)
.settings(publish := {})
.settings(
Seq(
packageName in Docker := "my-api",
dockerBaseImage := "java:8",
mainClass in Compile := Some("com.path.to.Main"),
publishArtifact := false,
unmanagedJars in Compile += file("jars/somejars.jar")
))
API is built on top of Finch framework. I create a docker image for the API using sbt api/docker:publishLocal and then run it locally. However, it seems like the utils subproject classes are not packaged with the final container, and as a result I am getting multiple
java.lang.ClassNotFoundException:
types of exceptions. For a similar project that doesn't have a subproject dependency, everything runs smoothly and I have no problems.
Am I missing something in the plugin configuration? I thought .dependsOn() should be taking care of providing dependent classes in the project docker image.
Answering my own question, but turns out this is a default behaviour of sbt-native-packager, or rather sbt, when a dependent project has publishArtifact := false setting.
A workaround that worked for me was changing the above to publish/skip := true.
More on this issue can be found here: https://github.com/sbt/sbt-native-packager/issues/1221

Scala, docker - how to set mainClass in multimodule application using sbt-native-packager?

I have created a multimodule, sbt project in Scala. For now it is:
main project (main-service) with build.sbt file
http module with Main class
In my sbt file I have:
lazy val root = (project in file("."))
.aggregate(http)
.settings(
dockerBaseImage := "openjdk:jre-alpine",
name := "main-service",
libraryDependencies ++= Seq(
)
)
.enablePlugins(JavaAppPackaging)
.enablePlugins(DockerPlugin)
.enablePlugins(AshScriptPlugin)
lazy val http = (project in file("http"))
.settings(
mainClass in Compile := Some("Main"),
name := "main-http",
libraryDependencies ++= Seq(
))
As you can see, I want to run it with docker. Image of this project is created well, but when I made docker run then I got an error:
docker: Error response from daemon: OCI runtime create failed: container_linux.go:345: starting container process caused "exec: \"/opt/docker/bin/main-service\": stat /opt/docker/bin/main-service: no such file or directory": unknown.
I think the problem could be with mainClass line. I have my Main class in main-http/src/main/scala directory, but it looks like docker does not see it.
How should I move this Main class or change path to it and run it correctly?
If you want to keep the main class in http subproject, you need to move the plugins to this project too as following.
lazy val root = (project in file("."))
.aggregate(http)
.settings(name := "main-service")
lazy val http = (project in file("http"))
.settings(
mainClass in Compile := Some("Main"),
dockerBaseImage := "openjdk:jre-alpine",
name := "main-http",
libraryDependencies ++= Seq()
)
.enablePlugins(JavaAppPackaging)
.enablePlugins(DockerPlugin)
.enablePlugins(AshScriptPlugin)
The plugins must be enabled at the project where the Main class is located.
To build a docker image, do
sbt http/docker:publishLocal

sbt multimodule project importing trait from another module

I have an sbt project with multiple modules, each with their own build.sbt file.
In the root project, I have the following:
lazy val commonSettings = Seq(
organization := "com.game.scala",
sourcesInBase := false,
fork in run := true,
scalaVersion := "2.12.1"
)
lazy val common = project.settings(commonSettings)
lazy val original = project.settings(commonSettings).dependsOn(common)
lazy val functional = project.settings(commonSettings).dependsOn(common)
lazy val root = (project in file("."))
.aggregate(original, functional)
.settings(commonSettings)
The build.sbt in all the submodules are pretty much the same:
lazy val module = (project in file("."))
.settings(
name := "Game subpart",
version := "0.1.0-SNAPSHOT"
)
And the layout of the project looks something like:
root
|__ common
|__ original
|__ functional
The problem is that from within the functional module, if I try importing a trait declared in common module, I get an error that it is not available:
Error:(1, 12) object game is not a member of package com
import com.game.scala
What am I missing?
This is because you never compiled your common project. The dependsOn method only add a dependency to the other project, but do no action on it, unless explicitly asked to. If you want your dependency to be re-compiled whenever the functional module is compiled, you should do both dependsOn(common) and aggregate(common).

Intertwined dependencies between sbt plugin and projects within multi-project build that uses the plugin itself

I'm developing a library that includes an sbt plugin. Naturally, I'm using sbt to build this (multi-project) library. My (simplified) project looks as follows:
myProject/ # Top level of library
-> models # One project in the multi-project sbt build.
-> src/main/scala/... # Defines common models for both sbt-plugin and framework
-> sbt-plugin # The sbt plugin build
-> src/main/scala/...
-> framework # The framework. Ideally, the sbt plugin is run as part of
-> src/main/scala/... # compiling this directory.
-> project/ # Multi-project build configuration
Is there a way to have the sbt-plugin defined in myProject/sbt-plugin be hooked into the build for myProject/framework all in a unified build?
Note: similar (but simpler) question: How to develop sbt plugin in multi-project build with projects that use it?
Is there a way to have the sbt-plugin defined in myProject/sbt-plugin be hooked into the build for myProject/framework all in a unified build?
I have a working example on Github eed3si9n/plugin-bootstrap. It's not super pretty, but it kind of works. We can take advantage of the fact that sbt is recursive.
The project directory is another build inside your build, which knows how to build your build. To distinguish the builds, we sometimes use the term proper build to refer to your build, and meta-build to refer to the build in project. The projects inside the metabuild can do anything any other project can do. Your build definition is an sbt project.
By extension, we can think of the sbt plugins to be library- or inter-project dependencies to the root project of your metabuild.
meta build definition (project/plugins.sbt)
In this example, think of the metabuild as a parallel universe or shadow world that has parallel multi-build structure as the proper build (root, model, sbt-plugin).
To reuse the source code from model and sbt-plugin subprojects in the proper build, we can re-create the multi-project build in the metabuild. This way we don't need to get into the circular dependency.
addSbtPlugin("com.eed3si9n" % "sbt-doge" % "0.1.5")
lazy val metaroot = (project in file(".")).
dependsOn(metaSbtSomething)
lazy val metaModel = (project in file("model")).
settings(
sbtPlugin := true,
scalaVersion := "2.10.6",
unmanagedSourceDirectories in Compile :=
mirrorScalaSource((baseDirectory in ThisBuild).value.getParentFile / "model")
)
lazy val metaSbtSomething = (project in file("sbt-plugin")).
dependsOn(metaModel).
settings(
sbtPlugin := true,
scalaVersion := "2.10.6",
unmanagedSourceDirectories in Compile :=
mirrorScalaSource((baseDirectory in ThisBuild).value.getParentFile / "sbt-plugin")
)
def mirrorScalaSource(baseDirectory: File): Seq[File] = {
val scalaSourceDir = baseDirectory / "src" / "main" / "scala"
if (scalaSourceDir.exists) scalaSourceDir :: Nil
else sys.error(s"Missing source directory: $scalaSourceDir")
}
When sbt loads up, it will build metaModel and metaSbtSomething first, and use metaSbtSomething as a plugin to your proper build.
If you have any other plugins you need you can just add it to project/plugins.sbt normally as I've added sbt-doge.
proper build (build.sbt)
The proper build looks like a normal multi-project build.
As you can see framework subproject uses SomethingPlugin. Important thing is that they share the source code, but the target directory is completely separated, so there are no interference once the proper build is loaded, and you are changing code around.
import Dependencies._
lazy val root = (project in file(".")).
aggregate(model, framework, sbtSomething).
settings(inThisBuild(List(
scalaVersion := scala210,
organization := "com.example"
)),
name := "Something Root"
)
// Defines common models for both sbt-plugin and framework
lazy val model = (project in file("model")).
settings(
name := "Something Model",
crossScalaVersions := Seq(scala211, scala210)
)
// The framework. Ideally, the sbt plugin is run as part of building this.
lazy val framework = (project in file("framework")).
enablePlugins(SomethingPlugin).
dependsOn(model).
settings(
name := "Something Framework",
crossScalaVersions := Seq(scala211, scala210),
// using sbt-something
somethingX := "a"
)
lazy val sbtSomething = (project in file("sbt-plugin")).
dependsOn(model).
settings(
sbtPlugin := true,
name := "sbt-something",
crossScalaVersions := Seq(scala210)
)
demo
In the SomethingPlugin example, I'm defining something task that uses foo.Model.x.
package foo
import sbt._
object SomethingPlugin extends AutoPlugin {
def requries = sbt.plugins.JvmPlugin
object autoImport {
lazy val something = taskKey[Unit]("")
lazy val somethingX = settingKey[String]("")
}
import autoImport._
override def projectSettings = Seq(
something := { println(s"something! ${Model.x}") }
)
}
Here's how we can invoke something task from the build:
Something Root> framework/something
something! 1
[success] Total time: 0 s, completed May 29, 2016 3:01:07 PM
1 comes from foo.Model.x, so this demonstrates that we are using the sbt-something plugin in framework subproject, and that the plugin is using metaModel.

Why does sbt create layers of projects and src in IDEA?

I am new to SBT and trying to build a project. My Build.scala looks like
lazy val ec = project.in(file("."))
.settings(commonSettings: _*)
.settings(name := "ec")
.aggregate(ahka, currentLogProcessor, main)
lazy val currentLogProcessor = project.in(file("currentLogProcessor"))
.settings(commonSettings: _*)
.settings(name := "currentlogprocessor")
.settings(
libraryDependencies += "com.myorg.util" % "LP" % "0.18.0-SNAPSHOT" % "provided"
)
lazy val main = project
.settings(commonSettings: _*)
.settings(name := "main")
When SBT refreshes in IntelliJ, I see following
As you could see, even if the settings looks same for currentLogProcessor and main, the project structure is very very different.
project inside currentLogProcessor looks good but project under main is layer with project and src
What is the issue here? How can I remove the layers of project inside project?
Thanks
Your projects ec and main share the same folder. Remove main or ec, or change "in file" for one of them.
lazy val main = project in file("another_path") ...
The answer by #ka4eli is correct, but I'd like to point out few issues with the build definition that can make understanding it so much painful.
Defining top-level aggregate project
lazy val ec = project.in(file("."))
.settings(commonSettings: _*)
.settings(name := "ec")
.aggregate(ahka, currentLogProcessor, main)
You don't need it whatsoever as it's defined automatically anyway - you're just repeating what sbt does implicitly. Just remove it from the build and add build.sbt with the following:
commonSettings
Use build.sbt for a project's build definition
lazy val currentLogProcessor = project.in(file("currentLogProcessor"))
.settings(commonSettings: _*)
.settings(name := "currentlogprocessor")
.settings(
libraryDependencies += "com.myorg.util" % "LP" % "0.18.0-SNAPSHOT" % "provided"
)
By default, lazy val's name is used to call a project project macro should point to, i.e. no need for in(file("currentLogProcessor")). The same applies to the name setting - you're using all-lowercase name that may or may not be needed.
Use build.sbt under currentLogProcessor directory to have the same effect:
name := "currentlogprocessor"
commonSettings
libraryDependencies += "com.myorg.util" % "LP" % "0.18.0-SNAPSHOT" % "provided"
It's that simple.
Apply the rules to the main project.
Have fun with sbt = it's so simple that people hardly accept it and mess up build definitions on purpose to claim otherwise :)