Getting a "ECONNREFUSED 0.0.0.0:5432" connection error on Docker Compose

Question

I have a Docker compose YML file that has 2 containers defined in it, and when I run my Docker compose, I get a "ECONNREFUSED 0.0.0.0:5432" error.

Looking at the error logs, the database server (Postgres) container is running & ready for incoming connections, but when the application (Node js app) container

The weird thing is that they're on the same network, and on both containers the "0.0.0.0:5432" port has been set & exposed, but they're still not connecting when the application container makes a database call (see below image)

Docker compose:

version: "3.3"

services:

    # container 1
    application:
        ports:
            - "8000:8000"
        build:
            context: .
            dockerfile: ./dockerfile-app
        volumes:
            - .:/docker-app
        depends_on:
            database:
                condition: service_healthy
        restart: 
            always
        networks:
            - one_network

    # container 2
    database:
        image:
            postgres:12.6
        ports:
            - "5432:5432"
        volumes:
            - ./postgres-data:/var/lib/postgresql/data
        healthcheck:
            test: ["CMD-SHELL", "pg_isready -U postgres"]
            interval: 5s
            timeout: 5s
            retries: 5
        environment:
            POSTGRES_DB: "postgres"
            POSTGRES_USER: "postgres"
            POSTGRES_PASSWORD: "postgres"
        restart: 
            always
        networks:
            - one_network

networks:
    one_network:

Dockerfile:

# Base image
FROM ubuntu:16.04

# System updates
ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update && apt -y install -y software-properties-common curl

# Install Nodejs
RUN curl -sL https://deb.nodesource.com/setup_14.x | bash - && apt install -y nodejs

# Copy bash file for post-build tasks
WORKDIR /docker-app
COPY /docker-app.sh .

# Install Node packages
COPY /package.json .
RUN echo $PWD
RUN npm install

# Runs post-build commands
CMD ["sh", "./docker-app.sh"]

Can anyone help me understand why I'm getting this error please?

Answer 1

So I managed to solve this issue... which wasn't anything to do with Docker, but rather in my Node js app config:

module.exports = {
  client: 'pg',
  connection: {
    // host is the same name as the Docker container DB service
    host: 'database',
    port: '5432',
    user: 'postgres',
    password: 'postgres',
    database: 'postgres'
  },

Note: the 'host' variable, it's not localhost or 127.0.0.1 or anything similar. Rather it is the NAME of the container running the database (named above in my Docker Compose file)