test-with-docker.py runs the Impala build and tests inside of Docker containers, parallelizing the test execution across test suites. See that file for more details.
This also contains experimental infrastructure to build impala_base, catalogd, impalad and statestored container images from the output of an Impala build. The containers can be built via the CMake target docker_images. See CMakeLists.txt for the build targets.