码头工人撰写无法连接到PostgreSQL

Question

application.properties

spring.datasource.url=jdbc:postgresql://db:5432/test
spring.datasource.username=postgres
spring.datasource.password=123
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQL9Dialect
spring.jpa.hibernate.ddl-auto=create
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.properties.hibernate.id.new_generator_mappings=true
server.port=8000

docker-compose

version: '3.7'
services:

  db:
    image: postgres:11.4
    ports:
      - "5432:5432"
    expose:
      - 5432
    environment:
      POSTGRES_PASSWORD: "root"
      POSTGRES_DB: test

  lady:
    depends_on:
      - db
    build: ./test/
    ports:
      - "8000:8000"
    expose:
      - 8000
    environment:
      DB_USER: "postgres"
      DB_PASSWORD: "123"
      DB_TYPE: "postgres"
    command: ["java","-jar","test.jar"]

记录错误

com.women.lady.LadyApplicationTests > contextLoads() FAILED
    java.lang.IllegalStateException
        Caused by: org.springframework.beans.factory.BeanCreationException
            Caused by: javax.persistence.PersistenceException
                Caused by: org.hibernate.exception.JDBCConnectionException
                    Caused by: org.postgresql.util.PSQLException
                        Caused by: java.net.UnknownHostException

运行docker compose时，我无法连接到postgres或db： docker-compose up

问题

如何在docker-compose上连接数据库。 请举个例子。