How to get sbt-assembly merge right?

Question

In our Scala/Scalatra project, we have this merge policy for the plugin sbt-assembly :

assemblyMergeStrategy in assembly := {
  case x =>
   val oldStrategy = (assemblyMergeStrategy in assembly).value
   oldStrategy(x)
}

[error] 11 errors were encountered during merge java.lang.RuntimeException: deduplicate: different file contents found in the following: ~/.ivy2/cache/org.scalatra/scalatra_2.11/jars/scalatra_2.11-2.3.1.jar:mime.types ~/.ivy2/cache/com.amazonaws/aws-java-sdk-s3/jars/aws-java-sdk-s3-1.10.1.jar:mime.types

deduplicate: different file contents found in the following:
~/.ivy2/cache/commons-beanutils/commons-beanutils/jars/commons-beanutils-1.8.3.jar:org/apache/commons/collections/ArrayStack.class
~/.ivy2/cache/commons-collections/commons-collections/jars/commons-collections-3.2.1.jar:org/apache/commons/collections/ArrayStack.class
deduplicate: different file contents found in the following:

and the same error for different class names

What would be the right merge logic here?

Versions:

Scala : 2.11.7
SBT : 0.13.9
sbt-assembly: 0.13.0

Answer 1

I do not think, it is a matter of "merge-strategy", but more of the libs and their dependencies you are using.

Who "pulls" these dependencies? Which libraries are you using concretely?

One way to restrict is to use excludeAll (and similar) with dependency declaration. (see library management in SBT ), eg

excludeAll(
  ExclusionRule("commons-beanutils", "commons-beanutils-core"),
  ExclusionRule("commons-collections", "commons-collections"),
  ExclusionRule("commons-logging", "commons-logging"),
  ExclusionRule("org.slf4j", "slf4j-log4j12"),
  ExclusionRule("org.hamcrest", "hamcrest-core"),
  ExclusionRule("junit", "junit"),
  ExclusionRule("org.jboss.netty", "netty"),
  ExclusionRule("com.esotericsoftware.minlog", "minlog")
  )

Answer 2

My original issue was solved with:

assemblyMergeStrategy in assembly := {
  case PathList("org", "apache", "commons", "collections", xs @ _*) =>
      MergeStrategy.last
  case PathList("mime.types") =>
      MergeStrategy.last
  case x =>
      val oldStrategy = (assemblyMergeStrategy in assembly).value
      oldStrategy(x)
}