Spring Boot与Actuator指标数据为空问题#28266

Hey there, let's work through this metrics issue you're hitting—since even a fresh Spring Boot 2.5.5 project has the same problem, it's likely a configuration oversight rather than a complex bug. Here's what to check step by step:

1. Verify Actuator Endpoint Exposure Configuration #

Spring Boot 2.x locks down most Actuator endpoints by default for security. You need to explicitly expose the metrics endpoint (or all endpoints) in your application.properties or application.yml:

For application.properties: #

# Expose all Actuator endpoints (adjust if you want to limit to specific ones)
management.endpoints.web.exposure.include=*
# Ensure the metrics endpoint is enabled (it's enabled by default, but good to confirm)
management.endpoint.metrics.enabled=true

For application.yml: #

management:
  endpoints:
    web:
      exposure:
        include: '*'
  endpoint:
    metrics:
      enabled: true

2. Confirm Dependencies Are Correct #

Double-check your build file to make sure you've included the necessary starters without conflicts.

Maven (pom.xml): #

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

Gradle (build.gradle): #

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-actuator'
}

3. Ensure You're Accessing the Correct Path #

Spring Boot 2.x uses /actuator as the default base path for all endpoints. So instead of hitting /metrics, you should visit:

http://localhost:8080/actuator/metrics

This should return a list of available metrics (like JVM memory stats, Tomcat session metrics, etc.) even without Spring Data/JPA. To see details for a specific metric, append its name—e.g., http://localhost:8080/actuator/metrics/jvm.memory.used.

4. Check Startup Logs for Endpoint Registration #

When your app starts, look for log lines like this:

Exposing X endpoint(s) beneath base path '/actuator'

Make sure metrics is listed in the exposed endpoints. If it's missing, double-check your configuration for typos (common issues include misspelling management or exposure).

5. Clear Build Cache (If Needed) #

For fresh projects that still have issues, sometimes cached dependencies can cause weird behavior. Try cleaning your Maven/Gradle cache and rebuilding the project:

• Maven: mvn clean install
• Gradle: ./gradlew clean build

If none of these steps fix the problem, let me know what you see when you visit /actuator/metrics (e.g., a blank response, 404 error, or empty JSON) and we can dig deeper!

内容的提问来源于stack exchange，提问作者user14774749