I have the staging and production environments on same VPS, so I can not use same port for these environments.

According the following docker-copmpose.yml, first we need to start the Database service, when run the migrations
by sh -c "npm run "Database migration", when start the web application by node FrontServerEntryPoint.js --environment staging:

version: "3.5"

services:

  front_server:

    image: example-front_server-staging
    container_name: Example-FrontServer-Staging
    build:
      context: .
      dockerfile: "FrontServer.Dockerfile"
    ports: [ "442:442" ]

    depends_on: [ Database ]
    command: sh -c "npm run "Database migration" && node FrontServerEntryPoint.js --environment staging"

  Database:

    image: postgres:16.2
    container_name: Example-Database-Staging
    ports: [ "5431:5432" ]

    environment:

      - TZ="Asia/Tokyo"
      - POSTGRES_PASSWORD=EXAMPLE-NOTHING_TO_STEAL

    volumes:
      - DatabaseData:/data/example.jp

volumes:
  DatabaseData:
    name: Example-DatabaseData-Staging
    driver: local

Although the FrontServer.Dockerfile does not matter for this question, I’ll post it to make you sure the it is so:

FROM node:22-alpine

WORKDIR /var/www/example.com

COPY . /var/www/example.com

RUN npm install --no-package-lock

When I have run the migrations, I got the following error:

Example-Production-FrontServer  | Error: connect ECONNREFUSED 172.18.0.2:5431
Example-Production-FrontServer  |     at TCPConnectWrap.afterConnect [as oncomplete] (node:net:1606:16) {
Example-Production-FrontServer  |   errno: -111,
Example-Production-FrontServer  |   code: 'ECONNREFUSED',
Example-Production-FrontServer  |   syscall: 'connect',
Example-Production-FrontServer  |   address: '172.18.0.2',
Example-Production-FrontServer  |   port: 5431
Example-Production-FrontServer  | }

I can’t publish the IP address of my VPS, but connection from the local machine via this IP address and 5431 works fine:

I to change ports: [ "5431:5432" ] to ports: [ "5432:5432" ] everything will work, but as I have said previously, it will not the solution in my case.

Looks like I have not understood the meaning of ports: [ "5431:5432" ]. The connection for the first port will be available from the outside, but don’t the second one actual only for Example-Database-Staging container?