my docker-compose file for fileserving question

file.docker

version: "3"  
services:  
  db:
    restart: always
    build: ./db
    environment:
      POSTGRES_USER: patientplatypus
      POSTGRES_PASSWORD: SUPERSECRETPASSD00T
      POSTGRES_DB: zennify
    expose:
      - "5432"
    ports:
      - 5432:5432
    volumes:
      - ./db/pgdata:/var/lib/postgresql/data
  app:
    restart: always
    build: 
      context: .
      dockerfile: Dockerfile
    command: bash -c 'while !</dev/tcp/db/5432; do sleep 10; done; realize start --run'
    # command: bash -c 'while !</dev/tcp/db/5432; do sleep 10; done; go run main.go'
    ports:
      - 8000:8000
    depends_on:
      - db
    links:
      - db
    volumes:
      - ./:/go/src/github.com/patientplatypus/webserver/