我有docker compose文件。容器cucurbit后端依赖于db。它是一个java springboot后端，以postgres作为rdms。当我运行docker-compose up时，它说cucurbit数据库不存在。

cucurbit-backend |   .   ____          _            __ _ _
cucurbit-backend |  /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
cucurbit-backend | ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
cucurbit-backend |  \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
cucurbit-backend |   '  |____| .__|_| |_|_| |_\__, | / / / /
cucurbit-backend |  =========|_|==============|___/=/_/_/_/
cucurbit-backend |  :: Spring Boot ::                (v2.5.7)
cucurbit-backend | 
cucurbit-backend | 2023-03-17 16:44:06.632  INFO 1 --- [           main] c.z.cucurbit.CucurbitApplication         : Starting CucurbitApplication using Java 11.0.18 on d841a735fe8f with PID 1 (/app.jar started by root in /)
cucurbit-backend | 2023-03-17 16:44:06.634  INFO 1 --- [           main] c.z.cucurbit.CucurbitApplication         : No active profile set, falling back to default profiles: default
cucurbit-backend | 2023-03-17 16:44:07.289  INFO 1 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
cucurbit-backend | 2023-03-17 16:44:07.338  INFO 1 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 42 ms. Found 4 JPA repository interfaces.
cucurbit-backend | 2023-03-17 16:44:07.778  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
cucurbit-backend | 2023-03-17 16:44:07.787  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
cucurbit-backend | 2023-03-17 16:44:07.788  INFO 1 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.55]
cucurbit-backend | 2023-03-17 16:44:07.828  INFO 1 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
cucurbit-backend | 2023-03-17 16:44:07.829  INFO 1 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1145 ms
cucurbit-backend | 2023-03-17 16:44:07.930  INFO 1 --- [           main] com.zeitgeist.cucurbit.CORSFilter        : Initializing CORSFilter...
cucurbit-backend | 2023-03-17 16:44:08.030  INFO 1 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
cucurbit-db | 2023-03-17 16:44:08.059 UTC [28] FATAL:  database "cucurbit" does not exist
cucurbit-backend | 2023-03-17 16:44:09.079 ERROR 1 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Exception during pool initialization.
cucurbit-backend | 
cucurbit-backend | org.postgresql.util.PSQLException: FATAL: database "cucurbit" does not exist
cucurbit-backend |  at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2565) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.core.v3.QueryExecutorImpl.readStartupMessages(QueryExecutorImpl.java:2677) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.core.v3.QueryExecutorImpl.<init>(QueryExecutorImpl.java:147) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.core.v3.ConnectionFactoryImpl.openConnectionImpl(ConnectionFactoryImpl.java:273) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.core.ConnectionFactory.openConnection(ConnectionFactory.java:51) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.jdbc.PgConnection.<init>(PgConnection.java:225) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.Driver.makeConnection(Driver.java:465) ~[postgresql-42.2.24.jar!/:42.2.24]
cucurbit-backend |  at org.postgresql.Driver.connect(Driver.java:264) ~[postgresql-42.2.24.jar!/:42.2.24]

我已经将这些添加到环境变量中，但它并没有创建数据库：

environment:
      - POSTGRES_DB:cucurbit
      - POSTGRES_USER:postgres
      - POSTGRES_PASSWORD:password

以下是我的完整docker compose文件：

version: '2'

services:
  app:
    image: 'docker-spring-boot-postgres:latest'
    build:
      context: .
    container_name: cucurbit-backend
    depends_on:
      - db
    environment:
      - CUCURBIT_ENVIRONMENT_PROFILE=development
      - CUCURBIT_DATABASE_URL=jdbc:postgresql://cucurbit-db:5432/cucurbit
      - CUCURBIT_DATASOURCE_USERNAME=postgres
      - CUCURBIT_DATASOURCE_PASSWORD=password
      - CUCURBIT_EMAIL_SENDER_USERNAME=noreply.cucurbit@gmail.com
      - CUCURBIT_EMAIL_SENDER_PASSWORD=wakeuptellme1234.
      - CUCURBIT_EMAIL_NOTIFICATION_SEND_TO=jobskreya@gmail.com
    expose:
      - 8080
    ports:
      - 8080

  db:
    image: 'postgres:13.1-alpine'
    container_name: cucurbit-db
    hostname: cucurbit-db
    expose:
      - '5432'
    ports:
      - 5432:5432
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=password
      - POSTGRES_DB=cucurbit
    command: postgres -c 'create database cucurbit' dbname=cucurbit

我的docker-compose文件有什么问题？