How to cache SBT incremental compilation

Build Environment
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1

I am working to reduce the compile time for my build. Locally, SBT caches incremental compilations so that only files that are changed are re-compiled between builds. On circle ci, however, every build compiles all my source code, which takes 5 minutes.

I’ve tried adding this to my circle.yml, to no avail:

dependencies:
  cache_directories:
    - "~/.iv2"
    - "~/.sbt"
    - "target"
    - "project/target"

I get this error:

    sbt.InvalidScalaInstance: Scala instance doesn't exist or is invalid: 
    version 2.11.8, library jar: /home/ubuntu/my_project/lib_managed/jars/org.scala-lang/scala-library/scala-library-2.11.8.jar, compiler jar: /home/ubuntu/my_project/lib_managed/jars/org.scala-lang/scala-compiler/scala-compiler-2.11.8.jar

Has anyone been able to successfully cache incremental compilation from sbt so that on the next build only re-compiles the modified files?

------------------------------------------------SOLUTION----------------------------------------------------------------------------------

I added this to circle.yml and it worked. Reduced my compile time to 44s.

dependencies:
  cache_directories:
    - "~/.iv2"
    - "~/.sbt"
    - "lib_managed" #### <-- need this
    - "target"
    - "project/target"
1 Like
2

Reposting so we can mark as solved.

Thanks for posting the solution!