Attempt to move docker-client dependency back to the provided scope

build.sbt

@@ -12,6 +12,9 @@ javacOptions ++= Seq("-source", "1.8", "-target", "1.8")
 // put jdeb on the classpath for scripted tests
 classpathTypes += "maven-plugin"
 libraryDependencies ++= Seq(
+  // these dependencies have to be explicitly added by the user
+  "com.spotify" % "docker-client" % "8.14.3" % Provided,
+  "org.vafer" % "jdeb" % "1.7" % Provided artifacts Artifact("jdeb", "jar", "jar"),
   "org.apache.commons" % "commons-compress" % "1.18",
   // for jdkpackager
   "org.apache.ant" % "ant" % "1.10.5",
@@ -22,19 +25,8 @@ libraryDependencies ++= Seq(
 libraryDependencies ++= {
   (pluginCrossBuild / sbtVersion).value match {
     case v if v.startsWith("1.") =>
-      Seq(
-        "org.scala-sbt" %% "io" % "1.2.2",
-        // these dependencies have to be explicitly added by the user
-        // FIXME temporary remove the 'provided' scope. SBT 1.0.0-M6 changed the resolving somehow
-        "com.spotify" % "docker-client" % "8.14.3" /* % "provided" */,
-        "org.vafer" % "jdeb" % "1.7" % Provided artifacts Artifact("jdeb", "jar", "jar")
-      )
-    case _ =>
-      Seq(
-        // these dependencies have to be explicitly added by the user
-        "com.spotify" % "docker-client" % "8.14.3" % Provided,
-        "org.vafer" % "jdeb" % "1.7" % Provided artifacts Artifact("jdeb", "jar", "jar")
-      )
+      Seq("org.scala-sbt" %% "io" % "1.2.2")
+    case _ => Seq()
   }
 }
 

src/main/scala/com/typesafe/sbt/packager/docker/DockerSpotifyClientPlugin.scala

@@ -2,10 +2,8 @@ package com.typesafe.sbt.packager.docker
 
 import java.nio.file.Paths
 
-import com.spotify.docker.client.DockerClient.BuildParam
-import com.spotify.docker.client.messages.ProgressMessage
-import com.spotify.docker.client.{DefaultDockerClient, DockerClient, ProgressHandler}
 import com.typesafe.sbt.packager.universal.UniversalPlugin.autoImport.stage
+
 import sbt.Keys._
 import sbt._
 
@@ -63,6 +61,35 @@ object DockerSpotifyClientPlugin extends AutoPlugin {
     val log = streams.value.log
 
     val dockerDirectory = context.toString
+
+    val docker = new DockerClientTask()
+    docker.packageDocker(primaryAlias, aliases, dockerDirectory, log)
+  }
+
+  def dockerServerVersion: Def.Initialize[Task[Option[DockerVersion]]] = Def.task {
+    val docker = new DockerClientTask()
+    docker.dockerServerVersion()
+  }
+
+}
+
+/**
+  * == Docker Client Task ==
+  *
+  * This private class contains all the docker-plugin specific implementations. It's only invoked when the docker
+  * plugin is enabled and the `docker:publishLocal` task is called. This means that all classes in
+  * `com.spotify.docker.client._` are only loaded when required and allows us to put the dependency in the "provided"
+  * scope. The provided scope means that we have less dependency issues in an sbt build.
+  */
+private class DockerClientTask {
+  import com.spotify.docker.client.DockerClient.BuildParam
+  import com.spotify.docker.client.messages.ProgressMessage
+  import com.spotify.docker.client.{DefaultDockerClient, DockerClient, ProgressHandler}
+
+  def packageDocker(primaryAlias: DockerAlias,
+                    aliases: Seq[DockerAlias],
+                    dockerDirectory: String,
+                    log: Logger): Unit = {
     val docker: DockerClient = DefaultDockerClient.fromEnv().build()
 
     log.info(s"PublishLocal using Docker API ${docker.version().apiVersion()}")
@@ -80,9 +107,8 @@ object DockerSpotifyClientPlugin extends AutoPlugin {
     }
   }
 
-  def dockerServerVersion: Def.Initialize[Task[Option[DockerVersion]]] = Def.task {
+  def dockerServerVersion(): Option[DockerVersion] = {
     val docker: DockerClient = DefaultDockerClient.fromEnv().build()
     DockerVersion.parse(docker.version().version())
   }
-
 }