Minimal CircleCI 2.0 Scala build configuration with caching of Ivy/Maven dependencies

config.yml

version: 2
jobs:
  build:
    docker:
      - image: circleci/openjdk:8-jdk
    steps:
      - checkout
      - restore_cache:
          key: scala-library-dependencies-{{ checksum "build.sbt" }}
      - run: sbt test:compile
      - save_cache:
          paths: [ "~/.m2", "~/.ivy2", "~/.cache/coursier" ]
          key: scala-library-dependencies-{{ checksum "build.sbt" }}
      - run: sbt test

Note. You may need to add this to your build.sbt to work around some weird filesystem restriction:

scalacOptions ++= Seq("-Xmax-classfile-name", "240")

See here for information: https://stackoverflow.com/questions/45022231/getting-file-name-too-long-when-running-tests-on-circleci

what about cache of the sbt launcher itself?

I came up with:

version: 2
jobs:
  build:
    docker:
    - image: circleci/openjdk:8-jdk
  
    working_directory: ~/repo

    environment:
      JVM_OPTS: -Xmx3200m
      TERM: dumb

    steps:
    - checkout

    - restore_cache:
        keys:
        - sbt-scala-cache-{{ checksum "build.sbt" }}

    - run: sbt clean test:compile

    - save_cache:
        paths: ["/home/circleci/.m2", "/home/circleci/.ivy2/cache", "/home/circleci/.coursier/cache", "/home/circleci/.sbt/launchers", "/home/circleci/.cache/coursier"]
        key: sbt-scala-cache-{{ checksum "build.sbt" }}

    - run: sbt test

This caches all the libs and the sbt launcher.

~/.cache/coursier -> ~/.coursier/cache ?

~/.cache/coursier is correct