Spring Boot切换PostgreSQL后启动报错：无法加载SQLServer驱动

原本使用SQL Server的Spring Boot应用，切换到Docker Compose部署的PostgreSQL容器并集成Flyway后，执行docker-compose up时仍出现找不到SQL Server驱动的错误。

错误信息 #

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'flyway' defined in class path resource [org/springframework/boot/autoconfigure/flyway/FlywayAutoConfiguration$FlywayConfiguration.class]: Bean instantiation via factory method failed; 
nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.flywaydb.core.Flyway]: Factory method 'flyway' threw exception; 
nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceConfiguration$Hikari.class]: Bean instantiation via factory method failed; 
nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.zaxxer.hikari.HikariDataSource]: Factory method 'dataSource' threw exception; 
nested exception is java.lang.IllegalStateException: Cannot load driver class: com.microsoft.sqlserver.jdbc.SQLServerDriver

相关配置 #

application.properties #

spring.datasource.username=${db_user}
spring.datasource.password=${db_pass}

# Hibernate ddl auto (create, create-drop, validate, update)
spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.PostgreSQLDialect
spring.datasource.url=jdbc:postgresql://${db_host}:5432/test
spring.jpa.hibernate.ddl-auto = validate

docker-compose.yml #

version: '2'
services:
  app:
    image: 'app:latest'
    build:
      context: .
    container_name: app
    depends_on:
      - db
    environment:
      - ENV=local
      - db_user=test
      - db_pass=test
      - dh_host=db
    ports:
      - "5050:8080"

  db:
    image: 'postgres:13.1-alpine'
    container_name: db
    environment:
      - POSTGRES_USER=test
      - POSTGRES_PASSWORD=test

pom.xml #

<description>Demo project for Spring Boot</description>
<properties>
    <java.version>11</java.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.flywaydb</groupId>
        <artifactId>flyway-core</artifactId>
    </dependency>

    <dependency>
        <groupId>org.postgresql</groupId>
        <artifactId>postgresql</artifactId>
        <scope>runtime</scope>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

解决方案 #

问题出在以下几个地方，对应修复步骤：

1. 修正环境变量拼写错误
   docker-compose.yml里的dh_host=db是笔误，应该改为db_host=db。这个错误会导致application.properties中的${db_host}无法正确取值，Spring Boot可能 fallback 到旧的SQL Server残留配置，或无法识别PostgreSQL的JDBC URL。

2. 显式指定PostgreSQL驱动类
   在application.properties中添加驱动类配置，避免Spring Boot自动识别出错：

   spring.datasource.driver-class-name=org.postgresql.Driver
   

3. 清理旧镜像与残留配置

   • 检查项目中是否存在其他配置文件（如application-local.properties）、系统属性或环境变量残留SQL Server相关配置
   • 执行docker-compose down --rmi all清理旧镜像，再用docker-compose up --build重新构建并启动容器，确保应用使用最新配置

内容的提问来源于stack exchange，提问作者Manish