Introduction of Monitoring a web app

Application's Health + Metrics
Notice unwanted behavior
Monoliths as well as microservices
- Crucial in microservices architecture
"To measure is to know"

We are going to integrate Prometheus monitoring with a web application based on SpringBoot

We will use following:
- Spring Boot
- Spring Boot Actuator
- Micrometer
We are also going to do a demo with an example.

Spring Boot Actuator

Sub-Project of Spring boot
Production ready endpoints
/actuator is the common prefix of these endpoints
- Protected by default
- Adjustable in application.properties
  - Expose all: management.endpoints.web.exposure.include=*

Micrometer

Vendor-Neutral application metrics facade
Support for Prometheus and many others:
- AWS Cloudwatch, Datadog, InfluxDB/Telegraf, New Relic, ...
Transforms /actuator/metrics data into data your monitoring system understands
Only a vendor-specific micrometer dependency in your application is required

pom.xml example:

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

<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-core</artifactId>
</dependency>

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

SpringBoot

Code example

...
import io.micrometer.core.instrument.Metrics;
...
private Counter runCounter = Mitrics.counter("runCounter");
...
@GetMapping("/api/demo")
@Timed
public String apiUse() throws InterruptedException {
  runCounter.increment();
  log.info("Hello world app accessed on /api/demo");

  return "Hello world";
}