Depends on based on healthchecks.

docker-compose.yaml

version: '2.4'

volumes:
  db-data:


services:
  db:
    image: postgres:11-alpine
    environment:
      POSTGRES_USER: nats
      POSTGRES_PASSWORD: nats
      POSTGRES_DB: nats
    healthcheck:
      test: ["CMD","pg_isready"]
      start_period: 10s
      interval: 10s
      timeout: 5s
      retries: 2
    volumes:
    - db-data:/var/lib/postgresql/data
    - ./nats/postgres.db.sql:/docker-entrypoint-initdb.d/postgres.db.sql
    ports:
    - 5432:5432

  nats:
    image: nats-streaming:0.18-alpine
    command: '-m 8222 --store sql --sql_driver postgres --sql_source "dbname=nats user=nats password=nats host=db port=5432 sslmode=disable readTimeout=5s writeTimeout=5s"'
    ports:
      - 8222:8222
    depends_on:
      db:
        condition: service_healthy