Docker run does not pass exit code back to jenkins. This is a workaround for that.

jenkins_build_docker.bash

docker build --rm -t $JOB_NAME/$BUILD_NUMBER .
docker run $JOB_NAME/$BUILD_NUMBER | perl -pe '/Failed examples:/ && `echo "fail" > docker-tests-failed`'
 
if [ ! -f docker-tests-failed ]; then
  echo -e "No docker-tests-failed file. Apparently tests passed."
else
  echo -e "docker-tests-failed file found, so build failed."
  rm docker-tests-failed
  exit 1
fi