Wrong ip assignment docker-compose

Question

I am building a website and trying to deploy the whole stack using docker compose.
The website needs a database, an api, a middleware translation layer and a frontend that are all able to communicate with eachother.

I have understood that I might need a network. So I made one.
Problem is that all containers get random ip adresses within the ip range.
it seems aux_adresses does not do the thing I thought it did...

services:
    db:
        image: neo4j:community
        restart: unless-stopped
        volumes:
            - ./conf:/conf
            - ./data:/data
            - ./import:/import
            - ./logs:/logs
            - ./plugins:/plugins
        environment:
            # Raise memory limits
            - NEO4J_AUTH=neo4j/password
            - NEO4J_dbms_memory_pagecache_size=1G
            - NEO4J_dbms.memory.heap.initial_size=1G
            - NEO4J_dbms_memory_heap_max__size=1G
        ports:
            - 7474:7474
            - 7687:7687
        networks:
            - matrix-network
    api:
        build: ./api/.
        restart: unless-stopped
        ports:
            -   8000:8000
        networks:
            - matrix-network

    middleware:
        build:
            ./database-middleware/.
        restart: unless-stopped
        ports:
            -   4000:4000
        networks:
            - matrix-network

    web:
        build:
            ./.
        restart: unless-stopped
        ports:
            - "80:80"
        networks:
            - matrix-network



networks:
    matrix-network:
        ipam:
            driver: default
            config:
                - subnet: 172.28.0.0/16
                  ip_range: 172.28.5.0/24
                  gateway: 172.28.5.254
                  aux_addresses:
                      api:          172.28.1.5
                      db:           172.28.1.6
                      middleware:   172.28.1.7
                      web:          172.28.1.8

Answer 1

just use the service name instead of an ip.

so for example: http://middleware:4000 instead of the ip.

thx @tkausl