Docker port binding for Redis with Laravel Sail

I have a multiple Laravel local projects and I'm trying to change one projects Redis port, so that it doesn't conflict with another project.

Projects are one the same network so that they can communicate with one another, but they have separate Redis instances.

This is my Redis service inside docker-compose.yml

    redis:
        image: 'redis:alpine'
        ports:
            - '6380:6379'
        volumes:
            - 'sail-redis:/data'
        networks:
            - sail
        healthcheck:
            test: ["CMD", "redis-cli", "ping"]
            retries: 3
            timeout: 5s

I'm trying to have Redis available on port :6380.

In Docker Desktop I can see, that port bind seems to work correctly:

My .env redis section is stock, just changed the port to the new one:

REDIS_HOST=redis
REDIS_PASSWORD=null
REDIS_PORT=6380

Problem

When I try to run sail artisan cache:clear I always get RedisException Connection refused.

What I have tried

I've tried changing the REDIS_HOST environment variable to be exact as container name. Also tried clearing the config with sail artisan config:clear. All with no luck.

Note: for some reason the :6379 port is still accessible. I imagine that it shouldn't be as it should be binded to :6380

6380:6379 means port 6379 in the container is going to be available at 6380 on the host however when using sail your app is running in another container and not on the host.

The solution is to just change the port Redis is listening on you can modify your docker-compose file:

redis:
    image: 'redis:alpine'
    volumes:
        - 'sail-redis:/data'
    networks:
        - sail
    healthcheck:
        test: ["CMD", "redis-cli", "ping"]
        retries: 3
        timeout: 5s
    command:
        - redis-server
        - "--port"
        - "6380"

An alternative if you don't want to change the container command would be to configure your app to get to redis via the host:

REDIS_HOST=172.17.0.1
REDIS_PASSWORD=null
REDIS_PORT=6380

Here 172.17.0.1 is what is set up as the host IP of the docker network by default, however your value may vary

Connections between containers always use the standard port for the destination service; they do not consider ports: at all. No matter what you have ports: set to you should keep your current configuration

REDIS_HOST=redis
REDIS_PORT=6379

ports: are only needed if you need to access Redis from outside a container, maybe using redis-cli for debugging or for doing local development against the container Redis. If you don't need this, it's safe to just delete the ports: block entirely. If you do keep it, the second number needs to continue to be the standard port number 6379, so change the first port number to a non-conflicting port on the host.

Solved the issue by simply creating a separate network for shared communication which all separate Redis containers don't have access to. This allows me to leave default Redis configuration (except changing binded port to a unoccupied port, but as @david-maze said this doesn't actually have any affect for Redis).