Using Redis on Gitlab CI for a Rails project

I am trying to set up Gitlab CI for my Rails project and for this I need Redis. I have added redis to the config file but I am getting an error

Redis::CannotConnectError:
  Error connecting to Redis on 127.0.0.1:6379 (Errno::ECONNREFUSED)

I am using JWTSession for token-based authentication and this relies on Redis. This is my setup.

.gitlab-ci.yml

image: ruby:2.5.1

services:
  - postgres:10.1
  - redis:latest

variables:
  BUNDLE_PATH: vendor/bundle
  DISABLE_SPRING: 1
  DB_HOST: postgres
  REDIS_URL: redis

before_script:
  - apt-get update -qq && apt-get install nodejs -y
  - bundle check || bundle install --jobs $(nproc)
  - cp config/database.yml.ci config/database.yml
  - bundle exec rails db:create RAILS_ENV=test
  - bundle exec rails db:schema:load RAILS_ENV=test

stages:
  - test

Tests:
  stage: test
  script:
    - bundle exec rspec spec/
  only:
    - merge_requests

config/initializers/redis.rb

require 'redis'
$redis = Redis.new(url: 'redis://redis:6379/0')

config/initializers/jwt_sessions.rb

JWTSessions.encryption_key = Rails.application.credentials.secret_jwt_encryption_key
JWTSessions.token_store = :redis, {
  redis_url: 'redis://localhost:6379',
  token_prefix: 'jwt_'
}

I can't seem to figure out how to get this to work. Any hint will be appreciated. Thank you!

UPDATE

I've just tried the connect block, but got this error:

connect:
  # Connect to PostgreSQL database as user postgres, without password
  image: redis
  script:
  - redis-cli -h redis PING

Redis::CannotConnectError:
        Error connecting to Redis on localhost:6379 (Errno::EADDRNOTAVAIL)
--- Caused by: ---
      # Errno::EADDRNOTAVAIL:
      #   Cannot assign requested address - connect(2) for [::1]:6379