how to visualize prometheus endpoint metrics using grafana

prometheusnoob Source

I have a simple Spring-Boot application (with Maven), which I've instrumented using Prometheus to collect application-specific metrics. The instrumented Prometheus metrics are exposed on http://localhost:8080/prometheus by default, but I'm not sure how to visualize these metrics on Grafana. When I try to set the datasource in Grafana, I get an error:

HTTP Error Not Found

Grafana error when adding a new data source

Below is my working code, which exposes metrics on http:localhost:8080/prometheus

Example.java: Simply exposes a few endpoints. Instrumented so that Prometheus counts the number of times the /homepage endpoint is hit.

@SpringBootApplication
@RestController
public class Example {

    //Just a logger that keeps track of relevant information:
    private static final Logger LOGGER = Logger.getLogger(Example.class.getName());

    //counter for counting how many times an endpoint has been hit
    static final Counter myCounter = Counter.build()    
                                              .name("CounterName") //note: by convention, counters should have "_total" suffix
                                              .help("Total requests recorded by a specific endpoint")
                                              .labelNames("status")
                                              .register();

    //using a guage to set the time that a dummy process started, store the time it ends, and then calculate
    //the elapsed time between when the process started and when the process ended.
    static final Gauge myGauge =  Gauge.build()
                                .name("GaugeName")
                                .help("This is the Gauge help message")
                                .labelNames("label1")
                                .register();            

    @RequestMapping("/hello")
    String hello() {

        myCounter.labels("customLabel1").inc(); //increment the number of requests by one
        myGauge.labels("customLabel1").inc(3);
        LOGGER.log(Level.INFO, "Number of times /hello has been hit: " + myCounter.labels("customLabel1").get());
        LOGGER.log(Level.INFO, "Size of our Gauge: " + myGauge.labels("customLabel1").get());
        myGauge.labels("customLabel1").dec();
        LOGGER.log(Level.INFO, "size of out Gauge after decrementing by 1: " + myGauge.labels("customLabel1").get());

        return "Hello world! This is an example response!";
    }

    @RequestMapping("/homepage")
    String homePage() {

        myCounter.labels("customLabel2").inc(); //increment the number of requests by one
        LOGGER.log(Level.INFO, "Number of times /homepage has been hit: " + myCounter.labels("customLabel2").get());

        return "this is the home page!!";
    }


    public static void main(String[] args) throws Exception {
        SpringApplication.run(Example.class, args);
    }

}

MonitoringConfig.java: This is how Prometheus collects the application's metric information, and exposes them on localhostL8080/prometheus

@Configuration
public class MonitoringConfig {
    @Bean
    SpringBootMetricsCollector springBootMetricsCollector(Collection<PublicMetrics> publicMetrics){
        SpringBootMetricsCollector springBootMetricsCollector = new SpringBootMetricsCollector(publicMetrics);
        springBootMetricsCollector.register();

        return springBootMetricsCollector;
    }

    @Bean
    ServletRegistrationBean servletRegistrationBean() {
        DefaultExports.initialize();
        return new ServletRegistrationBean(new MetricsServlet(), "/prometheus");
    }
}

pom.xml: Project's Maven dependencies

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.example</groupId>
    <artifactId>springboot</artifactId>
    <version>0.0.1-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.8.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- Prometheus dependencies -->
        <!-- The client -->
        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient</artifactId>
            <version>0.1.0</version>
        </dependency>

        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient_spring_boot</artifactId>
            <version>0.1.0</version>
        </dependency>

        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient_servlet</artifactId>
            <version>0.1.0</version>
        </dependency>
        <!-- Hotspot JVM metrics -->
        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient_hotspot</artifactId>
            <version>0.1.0</version>
        </dependency>
        <!-- Exposition HTTPServer -->
        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient_httpserver</artifactId>
            <version>0.1.0</version>
        </dependency>
        <!-- Pushgateway exposition -->
        <dependency>
            <groupId>io.prometheus</groupId>
            <artifactId>simpleclient_pushgateway</artifactId>
            <version>0.1.0</version>
        </dependency>

        <!-- Spring Boot Actuator for exposing metrics -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
            <version>1.5.8.RELEASE</version>
        </dependency>

    </dependencies>


</project>
spring-bootmetricsgrafanaprometheusgrafana-templating

Answers

answered 5 months ago Marc #1

You need to point grafana at a prometheus server, not your application.

See the prometheus docs for more details on how to run prometheus and how to visualize prometheus metrics in grafana dashboards.

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