title: Gitlab-CI: Bind mount failed
body: <p>I am trying to configure Gitlab CI for my dockerized Symfony project.</p>
  
  <p>In the test phase, I try to start my docker-compose.yml, where one service needs a bind mount. My runner <strong>does see</strong> the folder, but I cannot use it.
  I get as test output:</p>
  
  <pre><code>$ docker-compose -f docker-compose_deploy.yml up -d
  Creating network "xxx_default" with the default driver
  Creating xxx_php_1   ... 
  Creating xxx_db_1    ... 
  
  Creating xxx_php_1   ... done
  Creating xxx_nginx_1 ... 
  
  Creating xxx_db_1    ... error
  
  ERROR: for xxx_db_1  Cannot start service db: Bind mount failed: '/backups' does not exists
  </code></pre>
  
  <p>To test that I included the command <code>ls /</code> in my <code>before_script</code> section. But it does show <code>/backups</code>, since I altered my runners' config.toml:</p>
  
  <pre><code>[[runners]]
    name = "main-runner"
    url = "https://gitlab.com/"
    token = "xyz"
    executor = "docker"
    [runners.docker]
      tls_verify = false
      image = "docker:latest"
      privileged = false
      disable_cache = false
      volumes = ["/var/run/docker.sock:/var/run/docker.sock","/volume1/docker/postgres-backup:/backups", "/cache"]
      shm_size = 0
    [runners.cache]
  </code></pre>
  
  <p>Here's the important part of my <code>.gitlab-ci.yml</code>:</p>
  
  <pre><code>before_script:
    - ls /
    - docker info
    - apk add --update py-pip &amp;&amp; pip install docker-compose
    - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN registry.gitlab.com
  
  build:
    stage: build
    script:
      - docker-compose -f docker-compose_deploy.yml build --pull 
  
  test1:
    stage: test
    script:
      - docker-compose -f docker-compose_deploy.yml up -d
      - docker exec registry.gitlab.com/xxx-group/xxx_php_1 bash docker/php-fpm/initialization.sh
      - docker exec registry.gitlab.com/xxx-group/xxx_php_1 bin/console app:initialize
      - docker exec registry.gitlab.com/xxx-group/xxx_php_1 ./vendor/bin/simple-phpunit
    after_script:
      - docker-compose -f docker-compose_deploy.yml down 
  </code></pre>
  
  <p>The docker-compose.yml is</p>
  
  <pre><code>volumes:
      pgdata:
  services:
      db:
          image: postgres:9-alpine
          volumes:
              - pgdata:/var/lib/postgresql/data
              - /backups:/backups
  </code></pre>
  
  <p>Although the built images cannot be executed, I can <code>inspect</code> them:
  And the volume in fact is not listed there!</p>
  
  <pre><code>"Volumes": {
                  "/var/lib/postgresql/data": {}
              }
  </code></pre>