How to use mysql service inside my custom service in bitbucket-pipelines

Hi,

The below one is the bitbucket-pipelines.yml 

image: ruby:2.4.5
options:  
  size: 2x
pipelines:  
  default:    
     - step: 
        name: Running Rspec        
        caches:
          - bundler
          - yarn

        script:
          - apt-get update
          - curl -sL https://deb.nodesource.com/setup_8.x | bash -
          - apt-get update && apt-get install -y nodejs
          - curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add -
          - apt-get update
          - apt-get install -y yarn
          - apt-get install -y mutt
          - cp Gemfile.CI Gemfile
          - bundle install
          - yarn install
          - rspec
        services:
          - mysql
          - elasticsearch
          - docker
definitions:
  services:
    mysql:
      image: mysql:5.6
      environment:
        MYSQL_DATABASE: "database_name"
        MYSQL_ROOT_PASSWORD: "password"
    elasticsearch:
      memory: 4096
      image: elasticsearch:6.4.0
    customservice:
       image: customservice
  caches:
    bundler: ./vendor
    yarn: ./node_modules

 I need some way to connect my customservice to mysql service.

CustomService will start a rails container on spinning a container.

while starting the container it needs to connect to mysql service. I have tried configuring the host as 127.0.0.1, localhost, mysql in the database.yml. But nothing worked

Please help me if I am doing something wrong.