Levantar un servidor de postgres mediante docker

 version: '3.5'
services:
  db:
    image: 'postgres:11-alpine'
    restart: always
    volumes:
      - './postgres_data:/var/lib/postgresql/data'
    container_name: postgresdb
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    ports:
      - '5432:5432' 
    networks:
      - proxynet
networks:
  proxynet:
    name: em-net