sbt: How can I add a local filesystem jar to my project?

I have a library compiled to a jar (not an sbt project, just the jar file) that's not available on a repository.

Is there a simple way to add a reference to the jar in the filesystem/project directly?

You can put the jar in your project's lib folder (create it if it doesn't exist), it will then appear on your project's unmanaged-classpath.

To publish a jar file locally, if you have an sbt project that produces the jar, it should be as simple as invoking "publish-local" to publish the jar to your local ivy repository so that you can use that jar in another one of your projects (on the same computer).

Your SBT project should be structured like this:

README.md
build.sbt
project/
src/
target/

Create a lib/ directory to add a JAR file (e.g. spark-daria_2.11-0.2.0.jar) to the project:

README.md
build.sbt
lib/
  spark-daria_2.11-0.2.0.jar
project/
src/
target/

The location of the lib/ directory should line-up with the output of the sbt "show unmanagedBase" command.

Refresh the project in your IDE and import the code just like you would import an external dependency.

import com.github.mrpowers.spark.daria.sql.DataFrameValidator

If you have multi-module project you should:

1. add lib to module dir (not to root). E.g., if you have module core, you should add jar to core/lib.
2. remove explicit dependency for specified jar in your build.sbt (or in another place). E.g., remove libraryDependencies += <your jar in lib>