Spring/Java Application Monitoring Basics - Part 3

Enable Prometheus Metrics in spring App

I assume you have Spring boot web application ready to use for this project. If not, please get started with spring boot project.

Spring actuator provides out of the box monitoring features for spring boot apps. Micrometer APIs are there in actuator bundle which supports multiple metrics systems. Curious to know why spring use micrometer APIs, please checkout this.

implementation 'org.springframework.boot:spring-boot-starter-actuator'

Spring actuator auto-configure package enables some built-in endpoints like actuator/health and actuator/info

To enable prometheus as actuator endpoint,

• Add implement prometheus dependency. Thus, two dependencies are added.

implementation 'org.springframework.boot:spring-boot-starter-actuator'
implementation 'io.micrometer:micrometer-registry-prometheus:1.10.6'

• Add the below config in application.properties.

management.endpoints.web.exposure.include=health,info,prometheus

On curling /actuator/prometheus, you can see the different set of metrics like CPU metrics, Uptime metrics, JVM metrics, Tomcat metrics, Logback metrics which are auto-configured in actuator project. Lets scrape and visualise them in next sections.

Scrape Spring Boot Metrics from Prometheus Server

To setup the Prometheus and Grafana in local, please refer Spring/Java Application Monitoring Basics - Part 2

Once the above set-up is done, below dashboard is available in Grafana localhost:3000 with prometheus server metrics.

In prometheus server, we have to set up the job to scrape the spring metrics available at /actuator/prometheus. To do so,

• Set up the below job in prometheus.yaml.

  - job_name: "spring-app"
    metrics_path: '/actuator/prometheus'
    scheme: 'http'
    static_configs:
      - targets: [ "[YOUR_SYSTEM_IP_ADDRESS]:8080" ]

• Re-start the docker using docker-compose up -d

Check your prometheus localhost:9090 with process_uptime_seconds. You can see the metric with job named spring-app has a positive value.

Note: Try with host.docker.internal in place of [YOUR_SYSTEM_IP_ADDRESS] . If it doesn't work, please use you system ip-address

Configure Grafana Dashboard for SpringBoot Web Application

Grafana labs provides multiple pre-built dashboards for Micrometer metrics.

• JVM (Micrometer) is the good candidate to start with. It uses tag called application to distinguish multiple applications in each query.

• Thus, Add the below config in application.properties and restart your spring application.

management.metrics.tags.application=${spring.application.name}

• Now you can see process_uptime_seconds query in prometheus have new label called application.

• Import the mentioned JVM (Micrometer) dashboard.

• Choose + -> Import -> 4701 in Import via Grafana.com -> Load

• Choose Prometheus as Prometheus datasource and click Import.

JVM dashboard is imported and it holds the below panels.

• Quick Facts

• I/O Overview

• JVM Memory

• JVM Misc

• JVM Memory Pools (Heap & Non-Heap)

• Garbage collection

• Classloading

• Buffer Pools