Spring CommandLineRunner结合Actuator：WebApplicationType.NONE控制台应用如何暴露Prometheus指标端点？

Got it, let's break down why this is happening and how to fix it. When you set WebApplicationType.NONE, Spring Boot disables all web-related auto-configuration—including the embedded server that Actuator relies on to expose HTTP endpoints. That's why your metrics endpoints aren't accessible. Here are three solid solutions depending on your needs:

Solution 1: Use JMX Endpoints + Prometheus JMX Exporter (No Web Server Required) #

If you want to avoid spinning up any web server entirely, this approach uses JMX to expose metrics, then lets Prometheus scrape them via a dedicated exporter.

1. Enable JMX endpoints in your application config (application.properties or application.yml):

   # Expose all JMX endpoints (restrict to metrics/prometheus if needed)
   management.endpoints.jmx.exposure.include=*
   management.endpoint.metrics.enabled=true
   management.endpoint.prometheus.enabled=true
   

2. Set up the Prometheus JMX Exporter:

   • Grab the latest JMX Exporter JAR from Maven Central.
   • Create a simple config.yaml to define metric scraping rules (this example captures all metrics):

     lowercaseOutputName: true
     rules:
       - pattern: '.*'
     

   • Start your application with the JMX agent attached:

     java -javaagent:./jmx_prometheus_javaagent-<version>.jar=9091:config.yaml -jar your-app.jar
     

   The exporter will run on port 9091, and Prometheus can scrape metrics from http://localhost:9091/metrics.

Solution 2: Spin Up a Lightweight Web Server for Actuator Endpoints #

If you don't mind a minimal web server running just for Actuator, this is the most straightforward approach.

Option A: Force web type while keeping console app behavior #

Adjust your main application class to explicitly enable servlet web support, even if you want a console-focused app:

@SpringBootApplication
public class ConsoleApp implements CommandLineRunner {

    public static void main(String[] args) {
        new SpringApplicationBuilder(ConsoleApp.class)
                .web(WebApplicationType.SERVLET) // Force servlet web environment
                .run(args);
    }

    @Override
    public void run(String... args) throws Exception {
        // Your periodic task logic here (pair with @EnableScheduling if using @Scheduled)
    }
}

Option B: Exclude unnecessary web config #

If you want to avoid loading full Spring MVC/Flux, exclude those auto-config classes:

@SpringBootApplication(exclude = {WebMvcAutoConfiguration.class, WebFluxAutoConfiguration.class})
public class ConsoleApp implements CommandLineRunner {
    // ... rest of your code
}

Then configure Actuator to expose HTTP endpoints:

management.endpoints.web.exposure.include=prometheus,metrics
management.server.port=8081 # Use a separate port to avoid conflicts
management.server.servlet.context-path=/actuator

Now you can access Prometheus metrics at http://localhost:8081/actuator/prometheus.

Solution 3: Push Metrics to Prometheus PushGateway #

If you prefer your console app to actively send metrics to Prometheus (instead of being scraped), use Micrometer's PushGateway integration.

1. Add PushGateway dependencies (Maven example):

   <dependency>
       <groupId>io.micrometer</groupId>
       <artifactId>micrometer-registry-prometheus</artifactId>
   </dependency>
   <dependency>
       <groupId>io.prometheus</groupId>
       <artifactId>simpleclient_pushgateway</artifactId>
   </dependency>
   

2. Configure PushGateway in your app config:

   management.metrics.export.prometheus.pushgateway.enabled=true
   management.metrics.export.prometheus.pushgateway.base-url=http://your-pushgateway-host:9091
   management.metrics.export.prometheus.pushgateway.job=your-console-app-name
   management.metrics.export.prometheus.pushgateway.push-rate=60s # Push metrics every minute
   

Your app will now send metrics directly to the PushGateway, and Prometheus can scrape the gateway instead of your app.

内容的提问来源于stack exchange，提问作者Jakub Bręk