title: Trying to connect GitLab-CE docker container to OpenLDAP docker container
body: <p>I'm new to Docker and I'm trying to do something with Docker Networking. I have two containers, one is GitLab, and the other OpenLDAP, and I hope that I can get my Gitlab server to be setup with OpenLDAP authentication. I have the two composes below. The Gitlab compose is mainly copy and paste, as I'm not actually 100% sure on what the settings are supposed to be for the environment variables in order to have it communicate internally with the OpenLDAP container. I was hoping they could communicate entirely internally through a user-defined bridge called "loworkNetwork" I started before starting these composes. </p>
  
  <p>Gitlab Docker-Compose</p>
  
  <pre><code>version: '2'
  
  services:
    web:
      image: 'gitlab/gitlab-ce:latest'
      restart: always
      hostname: 'gitlab'
      environment:
        GITLAB_OMNIBUS_CONFIG: |
          external_url 'my_external_url'
          # These settings are documented in more detail at
          # https://gitlab.com/gitlab-org/gitlab-ce/blob/a0a826ebdcb783c660dd40d8cb217db28a9d4998/config/gitlab.yml.example#L136
          gitlab_rails['ldap_enabled'] = true
          gitlab_rails['ldap_host'] = 'ldap-service'
          gitlab_rails['ldap_port'] = 389
          gitlab_rails['ldap_uid'] = 'uid'
          gitlab_rails['ldap_method'] = 'plain' # 'ssl' or 'plain'
          gitlab_rails['ldap_bind_dn'] = 'cn=admin,dc=my_external_url,dc=com'
          gitlab_rails['ldap_password'] = 'password'
          gitlab_rails['ldap_allow_username_or_email_login'] = true
          gitlab_rails['ldap_base'] = 'dc=my_external_url,dc=com' 
      ports:
        - '80:80'
        - '443:443'
        - '22:22'
      volumes:
        - '/srv/gitlab/config:/etc/gitlab'
        - '/srv/gitlab/logs:/var/log/gitlab'
        - '/srv/gitlab/data:/var/opt/gitlab'
      networks:
        - loworkNetwork
  networks:
    loworkNetwork:
      external: true
  </code></pre>
  
  <p>LDAP Services Docker-Compose</p>
  
  <pre><code>version: '2'
  
  services:
    openldap:
      image: osixia/openldap:latest
      environment:
        - LDAP_ORGANISATION="lowork"
        - LDAP_DOMAIN=my_external_url
        - LDAP_ADMIN_PASSWORD=password
      networks:
        - loworkNetwork
      hostname: ldap-service
  
    phpldapadmin:
      image: osixia/phpldapadmin:latest
      ports:
        - "8080:80"
      environment:
        - PHPLDAPADMIN_LDAP_HOSTS=openldap
        - PHPLDAPADMIN_HTTPS=false
      networks:
        - loworkNetwork
  
  networks:
    loworkNetwork:
      external: true
  </code></pre>