How to use Package Registry with SBT project?

*I want to upload my package to Gitlab Package Registry, using the plugin availaible at -> https://github.com/gilcloud/sbt-gitlab *

I fully followed the instructions given at the readme file. But when I am trying to use sbt publish I am getting error.

[error] (xProject / publishConfiguration) Repository for publishing is not specified.
[error] (tProject / publishConfiguration) Repository for publishing is not specified.

Any clue how to do it ? The maven way was quite simple, but facing lots of issue when using sbt.

Could you share a sanitized copy of your .sbt file(s), and some details on how the project is structured (if it isn’t singular/flat)?

Also, are you running sbt publish from within a GitLab CI/CD job, or outside?

I am running it inside sbt console in the IntelliJ IDE.
Here is the sbt

import sbt.Keys.{packageBin, packagedArtifacts, _}
import sbtassembly.AssemblyKeys.{assembly, assemblyMergeStrategy}

// Platform and framework versions.
val demoOrg = "com.demo"
val demoVersion = "1.0.0-SNAPSHOT"
val demoName = "demo"

val _javaVersion = "1.8"             // Valid values: "1.8"|"11"
val _scalaVersion = "2.12.12"        // Scala version must be compatible with Spark Scala version
val scalaMajorVersion = "2.12"      // Scala version must be compatible with Spark Scala version
val sparkVersion = "3.0.1"

val _javaOptions = Seq("-Xmx2G")
val _javacOptions = Seq("-source", _javaVersion, "-target", _javaVersion, "-Xlint", "-Xdiags:verbose")
ThisBuild / useCoursier := false

import com.gilcloud.sbt.gitlab.{GitlabCredentials,GitlabPlugin}

GitlabPlugin.autoImport.gitlabGroupId     :=  Some(101010)
GitlabPlugin.autoImport.gitlabProjectId   :=  Some(0101010)
GitlabPlugin.autoImport.gitlabDomain      :=  "gitlab.com"


// Alternatively for credential managment
// ideal for pulling artifacts locally and keeping tokens out of your source control
// see below for sample .credentials file
credentials += Credentials(Path.userHome / ".sbt" / ".credentials.gitlab")

val _scalacOptions =
  Seq(
    "-deprecation",                       // Emit warning and location for usages of deprecated APIs.
    "-encoding", "utf-8",                 // Specify character encoding used by source files.
    "-explaintypes",                      // Explain type errors in more detail.
    "-feature",                           // Emit warning and location for usages of features that should be imported explicitly.
    "-g:vars",
    "-language:_",
    "-language:existentials",             // Existential types (besides wildcard types) can be written and inferred
    "-language:experimental.macros",      // Allow macro definition (besides implementation and application)
    "-language:higherKinds",              // Allow higher-kinded types
    "-language:implicitConversions",      // Allow definition of implicit functions called views
    "-unchecked",                         // Enable additional warnings where generated code depends on assumptions.
    "-Xcheckinit",                        // Wrap field accessors to throw an exception on uninitialized access.
    "-Xexperimental",                     // Former graveyard for language-forking extensions.
    "-Xfatal-warnings",                   // Fail the compilation if there are any warnings.
    "-Xfuture",                           // Turn on future language features.
    "-Xlint:_",
    "-Xlint:adapted-args",                // Warn if an argument list is modified to match the receiver.
    "-Xlint:by-name-right-associative",   // By-name parameter of right associative operator.
    "-Xlint:constant",                    // Evaluation of a constant arithmetic expression results in an error.
    "-Xlint:delayedinit-select",          // Selecting member of DelayedInit.
    "-Xlint:doc-detached",                // A Scaladoc comment appears to be detached from its element.
    "-Xlint:inaccessible",                // Warn about inaccessible types in method signatures.
    "-Xlint:infer-any",                   // Warn when a type argument is inferred to be `Any`.
    "-Xlint:missing-interpolator",        // A string literal appears to be missing an interpolator id.
    "-Xlint:nullary-override",            // Warn when non-nullary `def f()' overrides nullary `def f'.
    "-Xlint:nullary-unit",                // Warn when nullary methods return Unit.
    "-Xlint:option-implicit",             // Option.apply used implicit view.
    "-Xlint:package-object-classes",      // Class or object defined in package object.
    "-Xlint:poly-implicit-overload",      // Parameterized overloaded implicit methods are not visible as view bounds.
    "-Xlint:private-shadow",              // A private field (or class parameter) shadows a superclass field.
    "-Xlint:stars-align",                 // Pattern sequence wildcard must align with sequence component.
    "-Xlint:type-parameter-shadow",       // A local type parameter shadows a type already in scope.
    "-Xlint:unsound-match",               // Pattern match may not be typesafe.
    "-Yno-adapted-args",                  // Do not adapt an argument list (either by inserting () or creating a tuple) to match the receiver.
    "-Ypartial-unification",              // Enable partial unification in type constructor inference
    "-Ywarn-dead-code",                   // Warn when dead code is identified.
    "-Ywarn-extra-implicit",              // Warn when more than one implicit parameter section is defined.
    "-Ywarn-inaccessible",                // Warn about inaccessible types in method signatures.
    "-Ywarn-infer-any",                   // Warn when a type argument is inferred to be `Any`.
    "-Ywarn-nullary-override",            // Warn when non-nullary `def f()' overrides nullary `def f'.
    "-Ywarn-nullary-unit",                // Warn when nullary methods return Unit.
    "-Ywarn-numeric-widen",               // Warn when numerics are widened.
    "-Ywarn-unused:implicits",            // Warn if an implicit parameter is unused.
    "-Ywarn-unused:imports",              // Warn if an import selector is not referenced.
    "-Ywarn-unused:locals",               // Warn if a local definition is unused.
    "-Ywarn-unused:params",               // Warn if a value parameter is unused.
    "-Ywarn-unused:patvars",              // Warn if a variable bound in a pattern is unused.
    "-Ywarn-unused:privates",             // Warn if a private member is unused.
    "-Ywarn-value-discard"                // Warn when non-Unit expression results are unused.
  )

// Common settings
lazy val commonSettings =
  Seq(organization := demoOrg,
      version := demoVersion,
      scalaVersion := _scalaVersion,
      scalacOptions := _scalacOptions,
      javacOptions := _javacOptions,
      javaOptions := _javaOptions,
      resolvers := Seq(Resolver.mavenCentral, Resolver.defaultLocal, Resolver.mavenLocal),
      fork := true)                    // Needed as SBT's classloader doesn't work well with Spark

// Assembly settings
val assemblySettings =
  Seq(assemblyOption in assembly := (assemblyOption in assembly).value.copy(includeScala = true,
                                                                            includeDependency = true),
      test in assembly := {},
      assemblyMergeStrategy in assembly :=
      {
        case PathList("META-INF", "hk2-locator", xs@_*)                  => MergeStrategy.discard
        case PathList("META-INF", "versions", xs@_*)                     => MergeStrategy.last
        case PathList("META-INF", "DISCLAIMER", xs@_*)                   => MergeStrategy.last
        case PathList("META-INF", "io.netty.versions.properties", xs@_*) => MergeStrategy.last
        case PathList("org", "aopalliance", xs@_*)                       => MergeStrategy.discard
        case PathList("org", "objectweb", "asm", xs@_*)                  => MergeStrategy.first
        case PathList("org", "xmlpull", "v1", xs@_*)                     => MergeStrategy.last
        case PathList("org", "objenesis", xs@_*)                         => MergeStrategy.last
        case PathList("javax", "activation", xs@_*)                      => MergeStrategy.last
        case PathList("javax", "el", xs@_*)                              => MergeStrategy.first
        case PathList("javax", "inject", xs@_*)                          => MergeStrategy.first
        case PathList("javax", "validation", xs@_*)                      => MergeStrategy.first
        case PathList("javax", "servlet", "jsp", xs@_*)                  => MergeStrategy.first
        case PathList("mozilla", "public-suffix-list.txt", xs@_*)        => MergeStrategy.last
        case PathList("org", "apache", "commons", "logging", xs@_*)      => MergeStrategy.last
        case "log4j.properties" | "module-info.class"                    => MergeStrategy.discard
        case x                                                           =>
          val oldStrategy = (assemblyMergeStrategy in assembly).value
          oldStrategy(x)
      },
      assemblyExcludedJars in assembly :=
      {
        val cp = (fullClasspath in assembly).value
        cp.filter(p => p.data.getName.startsWith("log4j-over-slf4j") ||
                       p.data.getName.startsWith("jcl-over-slf4j") ||
                       p.data.getName.startsWith("jul-to-slf4j") ||
                       p.data.getName.startsWith("slf4j-log4j"))
      })

// Root project: attempts to suppress empty root JAR generation failed so far.
lazy val rootProject = (project in file("."))
  .disablePlugins(sbtassembly.AssemblyPlugin)
  .settings(commonSettings,
            name := demoName,
            skip in packageBin := true,
            skip in publish := true,
            packagedArtifacts := Map.empty)
  .aggregate(commonProject, discoveryProject, catalogProject, clientProject)

// Attempt to suppress packaging and publishing of an empty root project artifact.
publishArtifact in rootProject := false
packagedArtifacts in rootProject := Map.empty

lazy val commonProject = (project in file("demo-common"))
  .disablePlugins(sbtassembly.AssemblyPlugin)
  .settings(commonSettings,
            name := "demo-demo-common",
            libraryDependencies += "org.apache.opennlp" % "opennlp-tools" % "1.9.2" % Compile,
            libraryDependencies += "com.squareup.okhttp3" % "okhttp" % "4.9.0" % Compile,
            libraryDependencies += "com.google.code.gson" % "gson" % "2.8.6" % Compile,
            libraryDependencies += "org.json" % "json" % "20200518" % Compile,
            libraryDependencies += "org.apache.commons" % "commons-lang3" % "3.10" % Compile,
            libraryDependencies += "org.slf4j" % "slf4j-api" % "1.7.30" % Provided,
            libraryDependencies += "org.slf4j" % "slf4j-log4j12" % "1.7.30" % Provided,
            libraryDependencies += "org.scalatest" %% "scalatest" % "3.1.1" % Test,
            libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.3" % Test)

lazy val discoveryProject = (project in file("demo-discovery"))
  .settings(commonSettings,
            name := "demo-demo-discovery",
            libraryDependencies += "com.h2database" % "h2" % "1.4.200" % Provided,
            libraryDependencies += "io.prestosql" % "presto-jdbc" % "338" % Provided,
            libraryDependencies += "org.testng" % "testng" % "7.1.0" % Test,
            libraryDependencies += "org.slf4j" % "slf4j-api" % "1.7.30" % Provided,
            libraryDependencies += "org.slf4j" % "slf4j-log4j12" % "1.7.30" % Provided,
            libraryDependencies += "org.scalatest" %% "scalatest" % "3.1.1" % Test,
            libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.3" % Test,
            assemblySettings)
  .dependsOn(commonProject)

lazy val catalogProject = (project in file("demo-catalog"))
  .settings(commonSettings,
            name := "demo-demo-catalog",
            libraryDependencies += "com.thoughtworks.paranamer" % "paranamer" % "2.8" % Compile,
            libraryDependencies += "net.sansa-stack" %% "sansa-rdf-spark" % "0.7.7-SNAPSHOT" % Compile,
            libraryDependencies += "org.apache.spark" %% "spark-core" % sparkVersion % Provided,
            libraryDependencies += "org.apache.spark" %% "spark-sql" % sparkVersion % Provided,
            libraryDependencies += "org.apache.spark" %% "spark-streaming" % sparkVersion % Provided,
            libraryDependencies += "org.apache.spark" %% "spark-graphx" % sparkVersion % Provided,
            dependencyOverrides += "org.slf4j" % "slf4j-api" % "1.7.30" % Provided,
            dependencyOverrides += "org.slf4j" % "slf4j-log4j12" % "1.7.30" % Provided,
            libraryDependencies += "org.scalatest" %% "scalatest" % "3.1.1" % Test,
            libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.3" % Test,
            assemblySettings,
            assemblyOption in assembly := (assemblyOption in assembly).value.copy(includeScala = false))
  .dependsOn(commonProject, discoveryProject)

lazy val clientProject = (project in file("demo-client"))
  .settings(commonSettings,
            name := "demo-demo-client",
            libraryDependencies += "org.apache.spark" %% "spark-core" % sparkVersion % Provided,
            libraryDependencies += "org.apache.spark" %% "spark-sql" % sparkVersion % Provided,
            libraryDependencies += "org.apache.spark" %% "spark-streaming" % sparkVersion % Provided,
            libraryDependencies += "org.apache.spark" %% "spark-graphx" % sparkVersion % Provided,
            dependencyOverrides += "org.slf4j" % "slf4j-api" % "1.7.30" % Provided,
            dependencyOverrides += "org.slf4j" % "slf4j-log4j12" % "1.7.30" % Provided,
            libraryDependencies += "org.scalatest" %% "scalatest" % "3.1.1" % Test,
            libraryDependencies += "org.scalacheck" %% "scalacheck" % "1.14.3" % Test,
            assemblySettings)
  .dependsOn(commonProject, catalogProject)