How to get sbt-assembly merge right? - scala

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 ), e.g.
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)
}