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
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>
