Windows Docker镜像中Spring Boot分层Jar加载外部配置报错解决

问题描述 #

运行基于Windows Docker镜像的Spring Boot分层Jar应用时，启动容器后触发FileNotFoundException，提示无法找到classpath下的SVMSController.properties。已将主机C:\my-app-props目录挂载到容器内C:/application/BOOT-INF/classes/config/路径，且确认容器内文件存在；Dockerfile中指定了--spring.config.location参数，应用代码通过@PropertySource注解引用配置文件，但仍报错。

报错日志 #

2022-09-06 13:03:15.746  INFO 1412 --- [           main] c.m.cdmf.svms.SVMSControllerApplication  : Starting SVMSControllerApplication v3.3.2-SNAPSHOT using Java 1.8.0_212 on 9aff754dd15d with PID 1412 (C:\application\BOOT-INF\classes started by ContainerAdministrator in C:\application)
2022-09-06T12:03:15.767885300Z 2022-09-06 13:03:15.746  INFO 1412 --- [           main] c.m.cdmf.svms.SVMSControllerApplication  : No active profile set, falling back to 1 default profile: "default"
2022-09-06T12:03:15.872396900Z 2022-09-06 13:03:15.855  WARN 1412 --- [           main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [com.mottmac.cdmf.svms.SVMSControllerApplication]; nested exception is java.io.FileNotFoundException: class path resource [SVMSController.properties] cannot be opened because it does not exist
2022-09-06T12:03:15.911392600Z 2022-09-06 13:03:15.887 ERROR 1412 --- [           main] o.s.boot.SpringApplication               : Application run failed
2022-09-06T12:03:15.911392600Z 
2022-09-06T12:03:15.911392600Z org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [com.mottmac.cdmf.svms.SVMSControllerApplication]; nested exception is java.io.FileNotFoundException: class path resource [SVMSController.properties] cannot be opened because it does not exist

Dockerfile #

FROM my.private.repo:5000/windows-java/8-jdk-windowsnanoserver-10.0.14393.1066:latest as builder
WORKDIR application
ARG JAR_FILE=target/*.jar
COPY ${JAR_FILE} application.jar
RUN powershell java -Djarmode=layertools -jar application.jar extract

FROM my.private.repo:5000/windows-java/8-jdk-windowsnanoserver-10.0.14393.1066:latest
WORKDIR application
COPY --from=builder application/dependencies/ ./
COPY --from=builder application/spring-boot-loader/ ./
COPY --from=builder application/snapshot-dependencies/ ./
COPY --from=builder application/application/ ./
EXPOSE 8080
ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher", "--spring.config.location=file:///C:/application/BOOT-INF/classes/config/SVMSController.properties"]

应用代码 #

@SpringBootApplication(exclude={DataSourceAutoConfiguration.class})
@PropertySource("classpath:SVMSController.properties")
public class SVMSControllerApplication implements ApplicationRunner
{
    public static void main(String[] args)
    {
        SpringApplication.run(SVMSControllerApplication.class);
    }
}

问题原因 #

• @PropertySource路径不匹配：@PropertySource("classpath:SVMSController.properties")期望文件在类路径根目录（即BOOT-INF/classes/下），但实际挂载的文件位于BOOT-INF/classes/config/子目录，类路径下找不到根目录的该文件。
• 配置加载方式独立：--spring.config.location是Spring Boot默认配置加载机制的扩展，而@PropertySource是显式指定的配置源，两者不会自动关联，指定spring.config.location不会让@PropertySource自动读取该路径的文件。

解决方案 #

方案一：修改@PropertySource路径 #

调整注解中的路径，指向配置文件实际的类路径位置：

@PropertySource("classpath:config/SVMSController.properties")

容器内C:/application/BOOT-INF/classes/是类路径根，config/SVMSController.properties对应实际文件位置，Spring可正常加载。

方案二：移除@PropertySource，依赖spring.config.location加载 #

删除代码中的@PropertySource注解，让Spring Boot通过指定的spring.config.location加载配置。同时调整Windows容器的路径格式（可简化file:///为file:）：

ENTRYPOINT ["java", "org.springframework.boot.loader.JarLauncher", "--spring.config.location=file:C:/application/BOOT-INF/classes/config/SVMSController.properties"]

方案三：调整挂载路径到类路径根 #

将主机目录直接挂载到容器的类路径根目录，让文件处于BOOT-INF/classes/下，匹配@PropertySource的路径要求：

docker run -v C:\my-app-props:C:/application/BOOT-INF/classes/ <镜像名>

内容的提问来源于stack exchange，提问作者Alex998