gitlab ci redis作为依赖服务

Question

I want to use Redis service as a dependency of my PHP/Nginx (Symfony application) application on GitlabCI and it should use the custom port. I already have Postgres added like this (I'll show just pieces of configurations):

variables:
    # POSTGRES - Use the values from the .env.test file.
    POSTGRES_DB: offers_test
    POSTGRES_USER: postgres
    POSTGRES_PASSWORD: asdfasdf

services:
    -   name: postgres:10
        # "postgresql" is what we use in the .env.test file
        alias: postgresql

here all is okay b-z Postgres image has a list of supported env variables and I can use them to configure Postgres connection.

But for Redis, I can't find any good image where I can configure a custom connection data. I only found official Gitlab documentation on how to use Redis service https://docs.gitlab.com/ee/ci/services/redis.html. So I add Redis to services

services:
    - redis:latest

And images built successfully, but on my tests, I'm getting the error like Error connecting to redis. Connection refused it's because CI connecting to Redis with default port, but I'm using a custom port. Any idea of how I can override connection details of Redis service?