why spring boot not load NacosConfigBootstrapConfiguration class

The issue of Spring Boot not loading the NacosConfigBootstrapConfiguration class often arises due to misconfigurations or compatibility issues between Spring Boot and Nacos. Here are the main reasons and solutions:

1. Spring Boot Version and Nacos Spring Boot Starter Version Mismatch

The NacosConfigBootstrapConfiguration class is part of the spring-cloud-alibaba or nacos-spring-boot dependencies. If there is a version mismatch between Spring Boot and the Nacos starter, the class may not be loaded.

Solution:

• Check your Spring Boot version.
• Ensure that the version of spring-cloud-alibaba or nacos-spring-boot you are using is compatible with your Spring Boot version.

For example:

• For Spring Boot 2.3.x, use spring-cloud-alibaba 2.2.x.RELEASE.
• For Spring Boot 2.5.x, use spring-cloud-alibaba 2021.x.

Refer to the official compatibility table for accurate version mappings.

2. Spring Boot Changed the Bootstrap Context in 2.4.x

Starting with Spring Boot 2.4, the bootstrap.properties or bootstrap.yml mechanism was replaced by the spring.config.import property. If you're using a version after Spring Boot 2.4.x, the configuration loading behavior has changed, and you might need to adjust your configuration files.

Solution:

• Migrate from bootstrap.yml to application.yml.
• Use spring.config.import=nacos: to explicitly define Nacos configuration.

Example:

spring: config: import: nacos://localhost:8848 nacos: config: server-addr: localhost:8848

3. Nacos Dependencies Missing in Classpath

If the NacosConfigBootstrapConfiguration class is not in your project, it might be due to missing or incorrectly included dependencies.

Solution:

Ensure you have the correct dependencies in your pom.xml (for Maven) or build.gradle (for Gradle).

For Maven:

<dependency> <groupId>com.alibaba.cloud</groupId> <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId> <version>2021.0.4.0</version> </dependency>

For Gradle:

implementation 'com.alibaba.cloud:spring-cloud-starter-alibaba-nacos-config:2021.0.4.0'

4. Incorrect Configuration in application.yml or bootstrap.yml

If the server-addr or other required properties are not specified correctly, Nacos will fail to initialize.

Solution:

Ensure your configuration file includes the necessary properties:

spring: cloud: nacos: config: server-addr: localhost:8848

5. Nacos Configuration Not Activated

If the application profile or configuration is not correctly set up, the Nacos configuration may not be activated.

Solution:

• Ensure you have the correct Spring profiles (application.properties or application.yml) activated.
• Check for spring.profiles.active in your configurations.

Debugging Steps

1. Check Logs: Look for any errors or warnings during application startup that reference Nacos configuration.
2. Enable Debug Logging: Add -Dlogging.level.com.alibaba.nacos=DEBUG to the JVM arguments to see detailed logs for Nacos.
3. Validate Dependencies: Use tools like mvn dependency:tree to ensure the required dependencies are correctly resolved.