sbt-docker | Create Docker images directly from sbt | Continuous Deployment library

To speed up our development workflow we split the tests and run each part on multiple agents in parallel. However, compiling test sources seem to take most of the time for the testing steps.

To avoid this, we pre-compile the tests using sbt test:compile and build a docker image with compiled targets.

Later, this image is used in each agent to run the tests. However, it seems to recompile the tests and application sources even though the compiled classes exists.

Is there a way to make sbt use existing compiled targets?

Update: To give more context

The question strictly relates to scala and sbt (hence the sbt tag).

Our CI process is broken down in to multiple phases. Its roughly something like this.

• stage 1: Use SBT to compile Scala project into java bitecode using sbt compile We compile the test sources in the same test using sbt test:compile The targes are bundled in a docker image and pushed to the remote repository,

• stage 2: We use multiple agents to split and run tests in parallel. The tests run from the built docker image, so the environment is the same. However, running sbt test causes the project to recompile even through the compiled bitecode exists.

To make this clear, I basically want to compile on one machine and run the compiled test sources in another without re-compiling

Update

I don't think https://stackoverflow.com/a/37440714/8261 is the same problem because unlike it, I don't mount volumes or build on the host machine. Everything is compiled and run within docker but in two build stages. The file modified times and paths are retained the same because of this.

The debug output has something like this