Don't compress debian packages

src/main/scala/com/typesafe/sbt/packager/debian/DebianPlugin.scala

@@ -158,7 +158,8 @@ object DebianPlugin extends AutoPlugin with DebianNativePackaging {
       (maintainerScripts in Debian).value,
       (linuxScriptReplacements in Debian).value,
       (target in Universal).value
-    )
+    ),
+    debianNativeBuildOptions := Nil
   )
 
   /**

src/main/scala/com/typesafe/sbt/packager/debian/Keys.scala

@@ -49,4 +49,6 @@ trait DebianKeys {
   val debianMakeChownReplacements = TaskKey[(String, String)]("debianMakeChownReplacements", "Creates the chown commands for correct own files and directories")
 
   val debianPackageInstallSize = TaskKey[Long]("debian-installed-size")
+
+  val debianNativeBuildOptions = SettingKey[Seq[String]]("debian-native-build-options", "Options passed to dpkg-deb, e.g. compression level")
 }

src/main/scala/com/typesafe/sbt/packager/debian/NativePackaging.scala

@@ -43,6 +43,7 @@ trait DebianNativePackaging extends DebianPluginLike {
    * package.
    */
   private[debian] def debianNativeSettings: Seq[Setting[_]] = inConfig(Debian)(Seq(
+    debianNativeBuildOptions += "-Znone", // packages are largely JARs, which are already compressed
     genChanges <<= (packageBin, target, debianChangelog, name, version, debianPackageMetadata) map {
       (pkg, tdir, changelog, name, version, data) =>
         changelog match {
@@ -81,12 +82,12 @@ trait DebianNativePackaging extends DebianPluginLike {
     },
 
     /** Implementation of the actual packaging  */
-    packageBin <<= (debianExplodedPackage, debianMD5sumsFile, debianSection, debianPriority, name, version, packageArchitecture, target, streams) map {
-      (pkgdir, _, section, priority, name, version, arch, tdir, s) =>
+    packageBin <<= (debianExplodedPackage, debianMD5sumsFile, debianSection, debianPriority, name, version, packageArchitecture, debianNativeBuildOptions, target, streams) map {
+      (pkgdir, _, section, priority, name, version, arch, options, tdir, s) =>
         s.log.info("Building debian package with native implementation")
         // Make the package.  We put this in fakeroot, so we can build the package with root owning files.
         val archive = archiveFilename(name, version, arch)
-        Process(Seq("fakeroot", "--", "dpkg-deb", "--build", pkgdir.getAbsolutePath, "../" + archive), Some(tdir)) ! s.log match {
+        Process(Seq("fakeroot", "--", "dpkg-deb", "--build") ++ options ++ Seq(pkgdir.getAbsolutePath, "../" + archive), Some(tdir)) ! s.log match {
           case 0 => ()
           case x => sys.error("Failure packaging debian file.  Exit code: " + x)
         }

src/sbt-test/debian/native-build-compress/build.sbt

@@ -0,0 +1,14 @@
+enablePlugins(DebianPlugin)
+
+debianNativeBuildOptions in Debian := Nil
+
+maintainer := "Maintainer <maintainer@example.com>"
+
+packageDescription := "Description"
+
+packageSummary := "Summary"
+
+TaskKey[Unit]("check-deb-compression") := {
+  val deb = target.value / s"${(name in Debian).value}_${(version in Debian).value}_all.deb"
+  assert(Seq("ar", "-t", deb.toString).lines.exists(_.startsWith("data.tar."))) // exact extension varies by dpkg-deb version
+}

src/sbt-test/debian/native-build-compress/project/plugins.sbt

@@ -0,0 +1 @@
+addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % sys.props("project.version"))

src/sbt-test/debian/native-build-compress/test

@@ -0,0 +1,2 @@
+> debian:packageBin
+> check-deb-compression

src/sbt-test/debian/native-build-default/build.sbt

@@ -0,0 +1,12 @@
+enablePlugins(DebianPlugin)
+
+maintainer := "Maintainer <maintainer@example.com>"
+
+packageDescription := "Description"
+
+packageSummary := "Summary"
+
+TaskKey[Unit]("check-deb-compression") := {
+  val deb = target.value / s"${(name in Debian).value}_${(version in Debian).value}_all.deb"
+  assert(Seq("ar", "-t", deb.toString).lines.contains("data.tar"))
+}

src/sbt-test/debian/native-build-default/project/plugins.sbt

@@ -0,0 +1 @@
+addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % sys.props("project.version"))

src/sbt-test/debian/native-build-default/test

@@ -0,0 +1,2 @@
+> debian:packageBin
+> check-deb-compression

src/sphinx/formats/debian.rst

@@ -56,6 +56,21 @@ Enable the debian plugin to activate the native package implementation.
 
   enablePlugins(DebianPlugin)
 
+Native packaging
+~~~~~~~~~~~~~~~~
+
+Since JARs are by default already compressed, `DebianPlugin` disables additional compression of the debian package
+contents.
+
+To compress the debian package, override `debianNativeBuildOptions` with
+`options <http://man7.org/linux/man-pages/man1/dpkg-deb.1.html>`_ for `dpkg-deb`.
+
+.. code-block:: scala
+
+  debianNativeBuildOptions in Debian := Nil // dpkg-deb's default compression (currently xz)
+
+  debianNativeBuildOptions in Debian := Seq("-Zgzip", "-z3") // gzip compression at level 3
+
 Java based packaging
 ~~~~~~~~~~~~~~~~~~~~