Merge pull request #652 from gzoller/wip/ash-doc

ash support documentation

src/main/resources/com/typesafe/sbt/packager/archetypes/ash-template

@@ -0,0 +1,36 @@
+#!/bin/sh
+
+realpath () {
+(
+  TARGET_FILE="$1"
+
+  cd "$(dirname "$TARGET_FILE")"
+  TARGET_FILE=$(basename "$TARGET_FILE")
+
+  COUNT=0
+  while [ -L "$TARGET_FILE" -a $COUNT -lt 100 ]
+  do
+      TARGET_FILE=$(readlink "$TARGET_FILE")
+      cd "$(dirname "$TARGET_FILE")"
+      TARGET_FILE=$(basename "$TARGET_FILE")
+      COUNT=$(($COUNT + 1))
+  done
+
+  if [ "$TARGET_FILE" == "." -o "$TARGET_FILE" == ".." ]; then
+    cd "$TARGET_FILE"
+    TARGET_FILEPATH=
+  else
+    TARGET_FILEPATH=/$TARGET_FILE
+  fi
+
+  echo "$(pwd -P)/$TARGET_FILE"
+)
+}
+
+real_script_path="$(realpath "$0")"
+app_home="$(realpath "$(dirname "$real_script_path")")"
+lib_dir="$(realpath "${app_home}/../lib")"
+
+${{template_declares}}
+
+java -classpath $app_classpath $app_mainclass $@

src/main/scala/com/typesafe/sbt/packager/archetypes/AshScriptPlugin.scala

@@ -73,15 +73,14 @@ import SbtNativePackager.{ Universal, Debian }
  */
 object AshScriptPlugin extends AutoPlugin {
 
-  val bashTemplate = "bash-template"
-
   override def requires = JavaAppPackaging
 
-  //object autoImport extends JavaAppKeys
-
   import JavaAppPackaging.autoImport._
 
+  val ashTemplate = "ash-template"
+
   override def projectSettings = Seq(
+    bashScriptTemplateLocation := (sourceDirectory.value / "templates" / ashTemplate),
     makeBashScript <<= (bashScriptTemplateLocation, bashScriptDefines, target in Universal, executableScriptName, sourceDirectory) map makeUniversalAshScript,
     bashScriptDefines <<= (Keys.mainClass in (Compile, bashScriptDefines), scriptClasspath in bashScriptDefines, bashScriptExtraDefines, bashScriptConfigLocation) map { (mainClass, cp, extras, config) =>
       val hasMain =

src/sphinx/formats/docker.rst

@@ -254,3 +254,24 @@ Now let's start adding some Docker commands.
     ExecCmd("CMD", "echo", "Hello, World from Docker")
   )
 
+Busybox/Ash Support
+~~~~~~~~~~~~~~~~~~~
+
+The default shell support for the Java archetype (JavaAppPackaging) is bash, with a Windows
+bat file also generated.  Busybox is a popular minimal Docker base image that uses ash, a much
+more limited shell than bash.  The result is that if you build a Docker image for Busybox the
+generated bash launch script will likely not work.
+
+Optionally you can use an ash-compatible archetype that derives from JavaAppPacking called
+AshScriptPlugin.  Enable this by including:
+
+.. code-block:: scala
+
+  enablePlugins(AshScriptPlugin)
+  
+With this plugin enabled an ash-compatible launch script will be generated in your Docker image.
+
+Just like for JavaAppPackaging you have the option of overriding the default script by supplying
+your own src/templates/ash-template file.  When overriding the file don't forget to include 
+${{template_declares}} somewhere to populate $app_classpath $app_mainclass from your sbt project.
+You'll likely need these to launch your program.