springboot2.4.x 项目启动报错无法识别bootstrap.yml配置

原因

SpringBoot项目，只会识别application.* 配置文件，并不会自动识别bootstrap.yml。

bootstrap.yml配置是SpringCloud项目才会用到的，如果你想在springboot项目中用bootstrap.yml，那么你需要添加bootstrap启动器。

从Spring Boot 2.4版本开始，配置文件加载方式进行了重构。官方说明：https://docs.spring.io/spring-cloud-config/docs/current/reference/html/#config-first-bootstrap

官方文档：

39.2. Config First Bootstrap

To use the legacy bootstrap way of connecting to Config Server, bootstrap must be enabled via a property or the spring-cloud-starter-bootstrap starter. The property is spring.cloud.bootstrap.enabled=true. It must be set as a System Property or environment variable.

 

优先级问题

由于SpringCloud是基于SpringBoot构建的，所有SpringCloud项目两种文件都会识别，这个时候才有优先级的说法，SpringCloud项目是会优先读取bootstrap配置在读取application配置。

SpringCloud应用是基于bootstrap的上下文运行的。

源码分析

源码调试发现问题出在SpringBoot2.4.3 在SpringApplication.prepareEnvironment() 这个方法中，environment.getProperty() 获取bootstrap文件默认设置为了false，导致无法读取bootstrap.properes\bootstrap.yml文件。

SpringBoot 2.3.12RELEASE

package org.springframework.cloud.bootstrap;/**
 * A listener that prepares a SpringApplication (e.g. populating its Environment) by
 * delegating to {@link ApplicationContextInitializer} beans in a separate bootstrap
 * context. The bootstrap context is a SpringApplication created from sources defined in
 * spring.factories as {@link BootstrapConfiguration}, and initialized with external
 * config taken from "bootstrap.properties" (or yml), instead of the normal
 * "application.properties".
 *
 * @author Dave Syer
 *
 */
public class BootstrapApplicationListener
        implements ApplicationListener<ApplicationEnvironmentPreparedEvent>, Ordered {

    /**
     * Property source name for bootstrap.
     */
    public static final String BOOTSTRAP_PROPERTY_SOURCE_NAME = "bootstrap";

    @Override
    public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
        ConfigurableEnvironment environment = event.getEnvironment();
        if (!environment.getProperty("spring.cloud.bootstrap.enabled", Boolean.class, true)) {
            return;
        }
      // 代码省略
 }

SpringBoot 2.4.3

package org.springframework.cloud.util;

import org.springframework.core.env.Environment;
import org.springframework.util.ClassUtils;

public abstract class PropertyUtils {
    public static final String BOOTSTRAP_ENABLED_PROPERTY = "spring.cloud.bootstrap.enabled";
    public static final String USE_LEGACY_PROCESSING_PROPERTY = "spring.config.use-legacy-processing";
    public static final String MARKER_CLASS = "org.springframework.cloud.bootstrap.marker.Marker";
    public static final boolean MARKER_CLASS_EXISTS = ClassUtils.isPresent("org.springframework.cloud.bootstrap.marker.Marker", (ClassLoader)null);

    private PropertyUtils() {
        throw new UnsupportedOperationException("unable to instatiate utils class");
    }

    public static boolean bootstrapEnabled(Environment environment) {
        return (Boolean)environment.getProperty("spring.cloud.bootstrap.enabled", Boolean.class, false) || MARKER_CLASS_EXISTS;
    }

    public static boolean useLegacyProcessing(Environment environment) {
        return (Boolean)environment.getProperty("spring.config.use-legacy-processing", Boolean.class, false);
    }
}

解决方法

1：添加bootstrap启动器:

        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-bootstrap</artifactId>
        </dependency>

2：启动参数设置

IDEA设置环境参数：select Run/Debug Configurations > Override parameters 中添加 spring.cloud.bootstrap.enabled 值为true。

命令行：java -jar -Dspring.cloud.bootstrap.enabled=true  test.jar

3：项目启动类新增系统变量spring.cloud.bootstrap.enabled=true

@EnableDiscoveryClient
@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        System.setProperty("spring.cloud.bootstrap.enabled", "true");
        SpringApplication.run(Application.class, args);
    }

}

 

参考：

SpringBoot 与 SpringCloud 版本说明：https://github.com/alibaba/spring-cloud-alibaba/wiki/%E7%89%88%E6%9C%AC%E8%AF%B4%E6%98%8E

SpringCloud 官方文档：https://docs.spring.io/spring-cloud-config/docs/current/reference/html/#config-first-bootstrap