Scala SBT Assembly cannot merge due to de-duplication error in StaticLoggerBinder.class

Question

My problem is I can no longer use the sbt-assembly plugin because some kind of dependency merge problem creeped in, between a couple people working on this project.

The

Answer 1

Previous answer gives all the required feedback, but does not actually give any solution or steps to try out.

My error:

[error] (project/*:assembly) deduplicate: different file contents found in the following:
[error] /home/user/.ivy2/cache/ch.qos.logback/logback-classic/jars/logback-classic-1.2.3.jar:org/slf4j/impl/StaticLoggerBinder.class
[error] /home/user/.ivy2/cache/org.slf4j/slf4j-log4j12/jars/slf4j-log4j12-1.7.10.jar:org/slf4j/impl/StaticLoggerBinder.class
[error] deduplicate: different file contents found in the following:
[error] /home/user/.ivy2/cache/ch.qos.logback/logback-classic/jars/logback-classic-1.2.3.jar:org/slf4j/impl/StaticMDCBinder.class
[error] /home/user/.ivy2/cache/org.slf4j/slf4j-log4j12/jars/slf4j-log4j12-1.7.10.jar:org/slf4j/impl/StaticMDCBinder.class
[error] deduplicate: different file contents found in the following:
[error] /home/user/.ivy2/cache/ch.qos.logback/logback-classic/jars/logback-classic-1.2.3.jar:org/slf4j/impl/StaticMarkerBinder.class
[error] /home/user/.ivy2/cache/org.slf4j/slf4j-log4j12/jars/slf4j-log4j12-1.7.10.jar:org/slf4j/impl/StaticMarkerBinder.class

Recommended way

track down conflicting dependency. For example, I do not want those classes:

org.slf4j/slf4j-log4j12/jars/slf4j-log4j12-1.7.10.jar:org/slf4j/impl/StaticLoggerBinder.class
org.slf4j/slf4j-log4j12/jars/slf4j-log4j12-1.7.10.jar:org/slf4j/impl/StaticMDCBinder.class
org.slf4j/slf4j-log4j12/jars/slf4j-log4j12-1.7.10.jar:org/slf4j/impl/StaticMarkerBinder.class

Call sbt (and make sure to use sbt-dependency-graph plugin):

whatDependsOn org.slf4j slf4j-log4j12 1.7.10

Returns a list:

[info] org.slf4j:slf4j-log4j12:1.7.10
[info]   +-org.apache.hadoop:hadoop-auth:2.8.0
[info]   | +-org.apache.hadoop:hadoop-common:2.8.0
[info]   |   +-com.github.atais:test_2.11:0.0.3 [S]
[info]   |   
[info]   +-org.apache.hadoop:hadoop-common:2.8.0
[info]   | +com.github.atais:test_2.11:0.0.3 [S]
[info]   | 
[info]   +-org.apache.zookeeper:zookeeper:3.4.6
[info]     +-org.apache.curator:curator-client:2.7.1
[info]     | +-org.apache.curator:curator-framework:2.7.1
[info]     | | +-org.apache.curator:curator-recipes:2.7.1
[info]     | | | +-org.apache.hadoop:hadoop-common:2.8.0
[info]     | | |   +-com.github.atais:test_2.11:0.0.3 [S]
[info]     | | |   
[info]     | | +-org.apache.hadoop:hadoop-auth:2.8.0
[info]     | |   +-org.apache.hadoop:hadoop-common:2.8.0
[info]     | |     +-com.github.atais:test_2.11:0.0.3 [S]
[info]     | |     
[info]     | +-org.apache.hadoop:hadoop-common:2.8.0
[info]     |   +-com.github.atais:test_2.11:0.0.3 [S]
[info]     |   
[info]     +-org.apache.curator:curator-framework:2.7.1
[info]     | +-org.apache.curator:curator-recipes:2.7.1
[info]     | | +-org.apache.hadoop:hadoop-common:2.8.0
[info]     | |   +-com.github.atais:test_2.11:0.0.3 [S]
[info]     | |   
[info]     | +-org.apache.hadoop:hadoop-auth:2.8.0
[info]     |   +-org.apache.hadoop:hadoop-common:2.8.0
[info]     |     +-com.github.atais:test_2.11:0.0.3 [S]
[info]     |     
[info]     +-org.apache.curator:curator-recipes:2.7.1
[info]     | +-org.apache.hadoop:hadoop-common:2.8.0
[info]     |   +-com.github.atais:test_2.11:0.0.3 [S]
[info]     |   
[info]     +-org.apache.hadoop:hadoop-auth:2.8.0
[info]     | +-org.apache.hadoop:hadoop-common:2.8.0
[info]     |   +-com.github.atais:test_2.11:0.0.3 [S]
[info]     |   
[info]     +-org.apache.hadoop:hadoop-common:2.8.0
[info]       +-com.github.atais:test_2.11:0.0.3 [S]

I need to track down hadoop-common dependency since it is the one that connects com.github.atais:test_2.11:0.0.3 to the unwanted org.slf4j:slf4j-log4j12:1.7.10

And modify it:

libraryDependencies += "org.apache.hadoop" % "hadoop-common" % "2.8.1" exclude("org.slf4j", "slf4j-log4j12")

Easy way

simply add the merging strategy flag for conflicting paths:

assemblyMergeStrategy in assembly := {
  ...
  case PathList("org", "slf4j", xs@_*) => MergeStrategy.first
  case x => (assemblyMergeStrategy in assembly).value(x)
}