How to sbt publish multi module project - scala

Question

I'm a complete beginner in sbt/scala. I have a multi module sbt project that I build with sbt assembly, which creates jar files of my modules. When I tried sbt module2/publish I noticed the output jar file in my directory is super slim compared to the jar files created by sbt-assembly and its throwing error when I tried to run:
Error: Unable to initialize main class
com.example.module2.service.Server
Caused by: java.lang.NoClassDefFoundError: scala/Function0
What do I need to include in my build.sbt file to make sbt publishing possible?
my-proj
├── Build.scala
├── common
│   ├── build.sbt
│   └── src
├── module1
│   ├── build.sbt
│   └── src
├── module2
│   ├── build.sbt
│   └── src
└── project
├── build.properties
└── plugins.sbt
Build.scala
lazy val my_proj = (project in file("."))
.aggregate(common, module1, module2)
lazy val common = project
lazy val common = (project in file("commons"))
lazy val module1 = (project in file("module1"))
.dependsOn(common, module2)
lazy val module1 = (project in file("module1"))
.dependsOn(common)
module1/build.sbt
name := "module1"
version := "0.1"
organization := "com.example"
scalaVersion := "2.11.12"
val akkaVersion = "2.5.16"
scalacOptions ++= Seq("-unchecked", "-deprecation", "-Xcheckinit", "-encoding", "utf8")
fork := true
/** Dependencies */
resolvers ++= Seq("Akka Repository" at "http://repo.akka.io/releases/",
"Typesafe Repository" at "http://repo.typesafe.com/typesafe/releases/"
)
publishTo := Some(Resolver.file("file", new File("/tmp/my/artifactory")))
libraryDependencies ++= Seq(
"org.scala-lang" % "scala-library" % scalaVersion
, "org.scala-lang" % "scala-compiler" % scalaVersion
, "org.scala-lang" % "scala-reflect" % scalaVersion
, "com.typesafe.akka" %% "akka-actor" % akkaVersion
)
assemblyMergeStrategy in assembly := {
case "META-INF\\io.netty.versions.properties" => MergeStrategy.first
case m if m.toLowerCase.endsWith("manifest.mf") => MergeStrategy.discard
case m if m.toLowerCase.matches("meta-inf.*\\.sf$") => MergeStrategy.discard
case m if m.toLowerCase.startsWith("meta-inf/services/") => MergeStrategy.filterDistinctLines
case "reference.conf" => MergeStrategy.concat
case _ => MergeStrategy.first
}

Answer 1

To publish a "fat" jar to a repository, you have to add the following to build.sbt of each sub-project you want to publish.
Compile / assembly / artifact ~= { art =>
art.withClassifier(Some("fat"))
}
addArtifact(Compile / assembly / artifact, assembly).settings