Directory structure 

This page assumes you’ve installed sbt and seen sbt by example.

Base directory 

In sbt’s terminology, the “base directory” is the directory containing the project. So if you created a project hello containing /tmp/foo-build/build.sbt as in the sbt by example, /tmp/foo-build is your base directory.

Source code 

sbt uses the same directory structure as Maven for source files by default (all paths are relative to the base directory):

src/
  main/
    resources/
       <files to include in main jar here>
    scala/
       <main Scala sources>
    scala-2.12/
       <main Scala 2.12 specific sources>
    java/
       <main Java sources>
  test/
    resources
       <files to include in test jar here>
    scala/
       <test Scala sources>
    scala-2.12/
       <test Scala 2.12 specific sources>
    java/
       <test Java sources>

Other directories in src/ will be ignored. Additionally, all hidden directories will be ignored.

Source code can be placed in the project’s base directory as hello/app.scala, which may be OK for small projects, though for normal projects people tend to keep the projects in the src/main/ directory to keep things neat. The fact that you can place *.scala source code in the base directory might seem like an odd trick, but this fact becomes relevant later.

sbt build definition files 

The build definition is described in build.sbt (actually any files named *.sbt) in the project’s base directory.

build.sbt

Build support files 

In addition to build.sbt, project directory can contain .scala files that define helper objects and one-off plugins. See organizing the build for more.

build.sbt
project/
  Dependencies.scala

You may see .sbt files inside project/ but they are not equivalent to .sbt files in the project’s base directory. Explaining this will come later, since you’ll need some background information first.

Build products 

Generated files (compiled classes, packaged jars, managed files, caches, and documentation) will be written to the target directory by default.

Configuring version control 

Your .gitignore (or equivalent for other version control systems) should contain:

target/

Note that this deliberately has a trailing / (to match only directories) and it deliberately has no leading / (to match project/target/ in addition to plain target/).