Improve Docker version detection

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

@@ -69,6 +69,13 @@ object DockerPlugin extends AutoPlugin {
   // Some of the default values are now provided in the global setting based on
   // sbt plugin best practice: https://www.scala-sbt.org/release/docs/Plugins-Best-Practices.html#Provide+default+values+in
   override lazy val globalSettings: Seq[Setting[_]] = Seq(
+    // See https://github.com/sbt/sbt-native-packager/issues/1187
+    // Note: Do not make this setting depend on the Docker version.
+    // Docker version may change depending on the person running the build, or even with something like
+    // `eval $(minikube docker-env)`.
+    // The Docker image the build creates should be repeatable regardless of who runs it as much as possible.
+    // Instead of making dockerPermissionStrategy dependent on the Docker version, what we do instead is to
+    // run validation, and warn the build users if the strategy is not compatible with `docker` that's in scope.
     dockerPermissionStrategy := DockerPermissionStrategy.MultiStage,
     dockerChmodType := DockerChmodType.UserGroupReadExecute
   )

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

@@ -5,11 +5,14 @@ import scala.util.matching.Regex
 case class DockerVersion(major: Int, minor: Int, patch: Int, release: Option[String])
 
 object DockerVersion {
-  private val DockerVersionPattern: Regex = "^'?([0-9]+).([0-9]+).([0-9]+)-?([-a-z0-9]+)?'?$".r
+  private val DockerVersionPattern: Regex = """^'?([0-9]+)\.([0-9]+)(\.[0-9]+)?(\W|_)?(.+)?'?$""".r
 
   def parse(version: String): Option[DockerVersion] =
     Option(version).collect {
-      case DockerVersionPattern(major, minor, patch, release) =>
-        new DockerVersion(major.toInt, minor.toInt, patch.toInt, Option(release))
+      case DockerVersionPattern(major, minor, patch, _, release) =>
+        new DockerVersion(major.toInt, minor.toInt, Option(patch) match {
+          case Some(p) => p.drop(1).toInt
+          case _       => 0
+        }, Option(release))
     }
 }

src/test/scala/com/typesafe/sbt/packager/docker/DockerVersionSpec.scala

@@ -0,0 +1,30 @@
+package com.typesafe.sbt.packager.docker
+
+import org.scalatest._
+
+class DockerVersionSpec extends FlatSpec with DiagrammedAssertions {
+  "DockerVersion" should "parse 18.09.2" in {
+    val v = DockerVersion.parse("18.09.2")
+    assert(v == Some(DockerVersion(18, 9, 2, None)))
+  }
+
+  it should "parse 18.06.1-ce" in {
+    val v = DockerVersion.parse("18.06.1-ce")
+    assert(v == Some(DockerVersion(18, 6, 1, Some("ce"))))
+  }
+
+  it should "parse 18.03.1-ee-8" in {
+    val v = DockerVersion.parse("18.03.1-ee-8")
+    assert(v == Some(DockerVersion(18, 3, 1, Some("ee-8"))))
+  }
+
+  it should "parse 18.09.ee.2-1.el7.rhel" in {
+    val v = DockerVersion.parse("18.09.ee.2-1.el7.rhel")
+    assert(v == Some(DockerVersion(18, 9, 0, Some("ee.2-1.el7.rhel"))))
+  }
+
+  it should "parse 17.05.0~ce-0ubuntu-xenial" in {
+    val v = DockerVersion.parse("17.05.0~ce-0ubuntu-xenial")
+    assert(v == Some(DockerVersion(17, 5, 0, Some("ce-0ubuntu-xenial"))))
+  }
+}