Docker-Compose container ip address with container name

My docker-compose have a two service, and docker-compose.yml define enviroment variable ip address with container name,

 version: '2'

services:
  api:
    build: ./api/
    command: python3 manage.py runserver
    volumes:
      - ./api:/code
    ports:
      - "8000:80"
    networks:
      - dock_net
    container_name: con_api

  web:
    build: ./web/
    command: python3 manage.py runserver
    volumes:
      - ./web:/code
    ports:
      - "8001:80"
    networks:
      - dock_net
    container_name: con_web
    environment:
        Ip:con_ip

networks:
  dock_net:
      driver: bridge

But variable see "con_ip" not 127.0.0.3