How to Track Spring Boot Configuration Values with /actuator/configprops

Background

When using Spring Boot for multi-environment packaging, configuration property values differ across environments, e.g.:

<code>spring:
  profiles:
    active: @project.profile@  # dynamically set profile via Maven
---
spring:
  profiles: dev
key: lengleng_dev
---
spring:
  profiles: prd
key: lengleng_prd
</code>

Or using Spring Cloud Config Center (Nacos, etc.).

The same property may come from configuration files, environment variables, or startup parameters, leading to unexpected values at runtime.

Solution

Spring Boot 2.3 Actuator provides the

/actuator/configprops

endpoint (previous versions also had

/actuator/env

) to track configuration file properties in real time.

How to Use

Include the Actuator dependency:

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

Expose the

configprops

endpoint:

<code>management:
  endpoints:
    web:
      exposure:
        include: 'configprops'
</code>

Create a configuration class:

<code>@Data
@Component
@ConfigurationProperties("demo")
public class DemoConfig {
    private String username;
    private String password;
}
</code>

Access the endpoint to get real-time property values.

Special Notes

The configprops endpoint masks sensitive fields by default, using keywords such as password, secret, key, token, .*credentials.*, vcap_services, sun.java.command.

<code>public class Sanitizer {
    private static final String[] REGEX_PARTS = { "*", "$", "^", "+" };
    private static final Set<String> DEFAULT_KEYS_TO_SANITIZE = new LinkedHashSet<>(Arrays.asList(
        "password", "secret", "key", "token", ".*credentials.*", "vcap_services", "sun.java.command"));
}
</code>

Customize sanitization rules:

<code>management:
  endpoint:
    configprops:
      keys-to-sanitize:
        - 'aaa'
        - 'bbb'
</code>

If a configuration property is null, it will not be displayed by the endpoint.

Summary

The configprops endpoint maps to

ConfigurationPropertiesReportEndpoint

and demonstrates how to retrieve configuration values from

PropertySource

.

Use case: CI pipelines should query this endpoint before running tests to ensure configurations match expectations.

Source code example: https://github.com/lltx/spring-boot-course