machine:
    pre:
        - echo 'DOCKER_OPTS="-s btrfs -e lxc -D"' | sudo tee -a /etc/default/docker
        - sudo curl -L -o /usr/bin/docker 'http://s3-external-1.amazonaws.com/circle-downloads/docker-1.6.2-circleci' && sudo chmod 0755 /usr/bin/docker
    java:
        version: oraclejdk8
    services:
        - docker

checkout:
    post:
        - git submodule update --init
        
test:
    override:
        - ./gradlew assemble
        - ./gradlew test && ./integration-tests.sh :
            timeout: 1800
    

machine:
    pre:
        - sudo curl -L -o /usr/bin/docker 'https://s3-external-1.amazonaws.com/circle-downloads/docker-1.9.0-circleci'
        - sudo chmod 0755 /usr/bin/docker
    java:
        version: oraclejdk8
    services:
        - docker

checkout:
    post:
        - git submodule update --init
        
test:
    override:
        - ./gradlew assemble
        - ./gradlew test && ./integration-tests.sh :
            timeout: 1800
    

Upgrade to Docker engine 1.9
Upgrade to Docker engine 1.9