Exit Code 255 on Docker exec command

docker

#1

I am running the tests with a docker exec command and I get the error below:

See my cicle.yml

machine:
  pre:
    - curl -sSL https://s3.amazonaws.com/circle-downloads/install-circleci-docker.sh | bash -s -- 1.10.0
    - curl -L https://github.com/docker/compose/releases/download/1.14.0/docker-compose-`uname -s`-`uname -m` > docker-compose 
    - sudo mv docker-compose /usr/local/bin/docker-compose
    - sudo chmod +x /usr/local/bin/docker-compose
  php:
    version: 7.1.3
  services:
    - docker

dependencies:
  override:
    - composer install
    - docker-compose -f docker-compose.prod.yml up -d

test:
  override:
    -  docker exec schools_web_1 scripts/wait-health.sh vendor/bin/phpunit

#2