I have a project where I am trying to create a fat jar using the sbt-assembly plugin. When I attempt to run my main class from the jar using the java -jar command, I get the error message: Error: Could not find or load main class com.gordon.timeshare.apps.TimeShareLauncher.
I only have one main class in my project (I use the extends App syntax to accomplish this), so I do not specify the path to the main class explicitly, although I have tried that and it did not help.
Below are all the settings I have in my build.sbt file.
ThisBuild / version := "0.1.0-SNAPSHOT"
ThisBuild / organization := "com.gordon.timeshare.apps"
ThisBuild / scalaVersion := "2.13.5"
lazy val app = (project in file("app"))
.settings(
assembly / mainClass := Some("com.gordon.timeshare.apps.TimeShareLauncher"),
assembly / assemblyJarName := "TimeShareLauncher.jar"
)
assemblyMergeStrategy in assembly := {
case PathList("META-INF", xs # _*) => MergeStrategy.discard
case x => MergeStrategy.first
}
I have also tried other strategies like deduplicate, but that would give me an error when trying to make the .jar.
Additionally, when making the .jar, I get a warning:
[warn] Could not create directory C:\Users\dgord\workspace\new-timeshare\timeshare\target\streams\_global\assembly\_global\streams\assembly\88fbe735ce5abc6987fbc59b072404628cdc94b4_a99f2fe2a42747ed9809d4f62f51a9e1b336dde8_da39a3ee5e6b4b0d3255bfef95601890afd80709\META-INF\versions\9: java.nio.file.FileAlreadyExistsException: C:\Users\dgord\workspace\new-timeshare\timeshare\target\streams\_global\assembly\_global\streams\assembly\88fbe735ce5abc6987fbc59b072404628cdc94b4_a99f2fe2a42747ed9809d4f62f51a9e1b336dde8_da39a3ee5e6b4b0d3255bfef95601890afd80709\META-INF\versions\9
And in case you want to know what my main class looks like:
package com.gordon.timeshare.apps
object TimeShareLauncher extends App
sbt: 1.4.7 (also tried 1.5.5)
sbt-assembly: 1.1.0
scala 2.13.5
I have also tried this on WSL and had the same result.
The issue is with lazy val app = (project in file("app")). Assuming a single module project with no module named app, sbt-assembly will create a directory named app and attempt to stuff the build in there. However, since the main class is not in the app bundle, the class will not be added to the jar file.
The correct way to do this is:
lazy val app = (project in file(".")), which specifies the current directory as the one to look for the main class. So this was not really an issue with knowing how to use the sbt-assembly plugin, but a more general issue with specifying projects in an sbt build.
Related
I'm trying to create a relatively simple sbt plugin to wrap grpc-swagger artifact.
Therefore, I've created a project with the following structure:
projectDir/
build.sbt
lib/grpc-swagger.jar <- the artifact I've downloaded
src/...
where build.sbt looks like the following:
ThisBuild / version := "0.0.1-SNAPSHOT"
ThisBuild / organization := "org.testPlugin"
ThisBuild / organizationName := "testPlugin"
lazy val root = (project in file("."))
.enable(SbtPlugin)
.settings(name := "grpc-swagger-test-plugin")
According to sbt docs, that's all I have to do in order to include an unmanaged dependecy, that is:
create a lib folder;
store the artifact in there;
However, when I do execute sbt compile publishLocal, the plugin published lacks of that external artifact.
So far I've tried to:
set exportJars := true flag
add Compile / unmanagedJars += file(lib/grpc-swagger.jar") (with also variations of the path)
manual fiddling to libraryDependecies using from file("lib/grpc-swagger.jar") specifier
but none so far seemed to work.
So how am I supposed to add an external artifact to a sbt plugin?
The proper solution to this problem is to publish the grpc-swagger library. If for whatever reason this can't be done from that library's build system, you can do it with sbt. Just add a simple subproject whose only job it is to publish that jar. It should work like so:
...
lazy val `grpc-swagger` = (project in file("."))
.settings(
name := "grpc-swagger",
Compile / packageBin := baseDirectory.value / "lib" / "grpc-swagger.jar",
// maybe other settings, such as grpc-swagger's libraryDependencies
)
lazy val root = (project in file("."))
.enable(SbtPlugin)
.settings(name := "grpc-swagger-test-plugin")
.dependsOn(`grpc-swagger`)
...
The pom file generated for the root project should now specify a dependency on grpc-swagger, and running the publish task in the grpc-swagger project will publish that jar along with a pom file.
That should be enough to make things work, but honestly, it's still a hack. The proper solution is to fix grpc-swagger's build system so you can publish an artifact from there and then just use it via libraryDependencies.
Following the hints of the post explaining the basics of migrating to scalajs and this page about cross-compilations, I decided to add cross compilation to my standalone dependency-free scala library by doing the following changes:
I added a file project/plugins.sbt with the content
addSbtPlugin("org.scala-js" % "sbt-scalajs" % "0.6.16")
I added scalaVersion in ThisBuild := "2.11.8" in build.sbt because else just scalaVersion was using 2.10
I also added in the build.sbt the following content to ensure that I can keep the same directory structure, since I don't have any particular files for the JVM or for Javascript:
lazy val root = project.in(file(".")).
aggregate(fooJS, fooJVM).
settings(
publish := {},
publishLocal := {}
)
lazy val foo = crossProject.crossType(CrossType.Pure).in(file(".")).
settings(version := "0.1").
jvmSettings(
// Add JVM-specific settings here
).
jsSettings(
// Add JS-specific settings here
)
lazy val fooJVM = foo.jvm
lazy val fooJS = foo.js
But now, after I published the project locally using sbt publish-local the projects depending on this library do not work anymore, i.e. they don't see the classes that this library was offering and raise errors.
I looked into .ivy2/local/.../foo/0.1/jars and the JAR went from 1MB to 1KB, so the errors make sense.
However, how can I make sure the JVM jar file is compiled correctly?
Further informations
The jar time does not change anymore, it looks like there had been some miscompilation. I deleted the .ivy2 cache, but now sbt publish-local always finishes with success but does not regenerate the files.
Ok I found the solution myself.
I needed to remove the publishLocal := {} from the build, and now all the projects depending on my library work fine.
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.
I am attempting to use SBT assembly(0.14.0) to create a fat jar of my Scala project.
My project structure is as follows:
>top
> build.sbt
> api
> src
> main
> scala
> name
> Boot.scala
> other directories
I am trying to set Boot as the main method to be run in the jar.
I have tried using:
baseDirectory in (Compile,run) := file("api")
scalaSource in run := baseDirectory.value / "api"
scalaSource in Compile := baseDirectory(_ / "api")
mainClass in assembly := some("name.Boot")
The jar builds successfully but when running it I receive the error:
Error: Could not find or load main class name.Boot
Going by the snippet you posted, you could try changing
mainClass in assembly := some("name.Boot")
to
mainClass in assembly := Some("name.Boot")
The reason it does not complain is that lower case some refers to something else.
The file path of your mainClass isn't relevant, only the namespace in Scala/Java. Is your main object
package name
object Boot {
def main ...
}
?
I need to build a single jar, including dependencies, for one of my sub-projects so that it can be used as a javaagent.
I have a multi-module sbt project and this particular module is the lowest level one (it's also pure Java).
Can I (e.g. with sbt-onejar, sbt-proguard or sbt assembly) override how the lowest level module is packaged?
It looks like these tools are really designed to be a post-publish step, but I really need a (replacement or additional) published artefact to include the dependencies (but only for this one module).
UPDATE: Publishing for sbt-assembly are instructions for a single project, and doesn't easily translate into multi-project.
Publishing for sbt-assembly are instructions for a single project, and doesn't easily translate into multi-project.
People have been publishing fat JAR using sbt-assembly & sbt-release without issues. Here's a blog article from 2011: Publishing fat jar created by sbt-assembly. It boils down to adding addArtifact(Artifact(projectName, "assembly"), sbtassembly.AssemblyKeys.assembly) to your build.sbt (note that the blog is a little out of date AssemblyKeys is now a member of sbtassembly directly).
For sbt 0.13 and above, I prefer to use build.sbt for multi-projects too, so I'd write it like:
import AssemblyKeys._
lazy val commonSettings = Seq(
version := "0.1-SNAPSHOT",
organization := "com.example",
scalaVersion := "2.10.1"
)
val app = (project in file("app")).
settings(commonSettings: _*).
settings(assemblySettings: _*).
settings(
artifact in (Compile, assembly) ~= { art =>
art.copy(`classifier` = Some("assembly"))
}
).
settings(addArtifact(artifact in (Compile, assembly), assembly).settings: _*)
See Defining custom artifacts:
addArtifact returns a sequence of settings (wrapped in a SettingsDefinition). In a full build configuration, usage looks like:
...
lazy val proj = Project(...)
.settings( addArtifact(...).settings : _* )
...