Connecting containers doesn't work in DigitalOcean

Hi all!

I have two different apps with two different docker-compose.yml files in different directories. I have a python flask app that fetches data from internet and stores it in a PostgreSQL database. This is working perfectly so far. This app should only accept connections from localhost. The second app is a Golang app that fetches data from internet but should also make requests to the first app, get that data and store it in a PostgreSQL database.

I have tried and my setup works perfectly in my local development machine, but it doesn’t work when it’s deployed in a droplet, and I’ve been trying for a week and I can’t find out why.

From my golang app code, I’m making a GET request to http://jobs-web:5000 or http://jobs:5000 and I’m getting an EOF error.

Here’s my two compose files:

First python app:

  web:
    container_name: jobs-web
    build: .
    command:
      [
        "gunicorn",
        "-b",
        "0.0.0.0:5000",
        "app:create_app()",
        "--log-level",
        "debug",
        "--access-logfile",
        "-",
        "--error-logfile",
        "-",
        "--timeout",
        "0",
        "--preload",
      ]
    environment:
      ENABLE_SCHEDULER: ${ENABLE_SCHEDULER}
      FLASK_ENV: production
      SQLALCHEMY_DATABASE_URI: ${SQLALCHEMY_DATABASE_URI}
    volumes:
      - .:/app
    depends_on:
      - db
    networks:
      - fullstack

  db:
    container_name: jobs-db
    image: postgres:16.4-alpine3.20
    restart: always
    environment:
      POSTGRES_USER: ${POSTGRES_USER}
      POSTGRES_PASSWORD: ${POSTGRES_PASSWORD}
      POSTGRES_DB: ${POSTGRES_DB}
    volumes:
      - postgres_data:/var/lib/postgresql/data
      - ./init-db.sh:/docker-entrypoint-initdb.d/init-db.sh
      - ./.env:/app/.env
    networks:
      - fullstack

networks:
  fullstack:
    external: true

volumes:
  postgres_data:
  test_postgres_data:

Second Goland app:

services:
  remoti-db:
    image: postgres:16.4-alpine3.20
    container_name: remoti-db
    ports:
      - 5432:5432
    restart: always
    environment:
      - POSTGRES_DB=${DB_NAME}
      - POSTGRES_USER=${DB_USERNAME}
      - POSTGRES_PASSWORD=${DB_PASSWORD}
    networks:
      - remoti-network
    volumes:
      - database_postgres:/var/lib/postgresql/data
    healthcheck:
      test: [CMD-SHELL, "pg_isready -U ${DB_USERNAME}"]
      interval: 3s
      timeout: 3s
      retries: 5
    expose:
      - "5432"

  app:
    build:
      context: .
      dockerfile: Dockerfile
    container_name: remoti-app
    ports:
      - 4000:4000
    depends_on:
      remoti-db:
        condition: service_healthy
    networks:
      - fullstack
      - remoti-network

  prometheus:
    image: prom/prometheus
    ports:
      - 9090:9090
    volumes:
      - prometheus:/prometheus
      - ./prometheus/development.yml:/etc/prometheus/prometheus.yml
    networks:
      - remoti-network

  grafana:
    image: grafana/grafana
    ports:
      - 3000:3000
    depends_on:
      - prometheus
    networks:
      - remoti-network
    volumes:
      - grafana:/var/lib/grafana
      - ./grafana/provisioning/datasources:/etc/grafana/provisioning/datasources
      - ./grafana/provisioning/dashboards:/etc/grafana/provisioning/dashboards
      - ./grafana/dashboards:/etc/dashboards
      - ./grafana/grafana.ini:/etc/grafana/grafana.ini

  migrations:
    image: migrate/migrate:latest
    env_file:
      - .env
    command: -path /migrations -database ${DSN} up
    volumes:
      - ./migrations:/migrations
    networks:
      - remoti-network
    depends_on:
      remoti-db:
        condition: service_healthy

volumes:
  database_postgres:
  migrations:
  prometheus:
  grafana:

networks:
  fullstack:
    external: true

  remoti-network:
    driver: bridge