如何在docker上连接rails和postgresql？正在获取:无法连接到服务器:连接被拒绝

version: '3'
services:
  web:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0'
    ports:
      - "3000:3000"
    depends_on:
      - db
  db:
    image: postgres:latest
    environment:
      POSTGRES_USER: your_postgres_username
      POSTGRES_PASSWORD: your_postgres_password

docker-compose up --build

default: &default
  adapter: postgresql
  encoding: unicode
  host: db
  username: your_postgres_username
  password: your_postgres_password
  pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
  <<: *default
  database: your_app_name_development

test:
  <<: *default
  database: your_app_name_test

docker-compose run web bundle exec rails db:create
docker-compose run web bundle exec rails db:migrate