Monitoring a Spring Boot application using Prometheus and Grafana

Greetings! In this article, we will demonstrate how to utilize Prometheus and Grafana for monitoring a Spring Boot application.

What is Prometheus?

Prometheus is a widely-used open-source toolkit for system monitoring and alerting, initially created at SoundCloud. Since its launch in 2012, it has gained popularity among various organizations and now boasts a vibrant community of developers and users. Prometheus became an independent open-source project, joining the Cloud Native Computing Foundation in 2016 as its second hosted project after Kubernetes.

For more information, visit the official documentation: https://prometheus.io/docs/introduction/overview/

Prometheus gathers and stores metrics as time series data, which means that the metrics are recorded with timestamps and can include optional key-value pairs known as labels.

What is Grafana Open Source?

Grafana is an open-source platform for data visualization and analytics, enabling users to query, visualize, alert on, and explore various metrics, logs, and traces, irrespective of where they are stored. It provides powerful tools to transform time-series database data into meaningful graphs and visualizations.

Spring Boot Application

We will initiate by creating a simple Spring Boot project through start.spring.io.

The spring-boot-actuator module offers all essential features for production readiness. Actuator endpoints allow for monitoring and interaction with the application. By default, web endpoints are not exposed; we need to enable them. We will expose the prometheus, health, and metrics endpoints as shown below:

management:

endpoint:

health:

show-details: always

show-components: always

endpoints:

web:

exposure:

include: ['health', 'prometheus', 'metrics']

To start our Spring Boot API, we can use the following command:

./mvnw spring-boot:run

Once the application is running, visit http://localhost:8080/actuator to see all available endpoints. The endpoint we will use for monitoring is http://localhost:8080/actuator/prometheus.

Setting Up Prometheus and Grafana via Docker

#### Configuring Prometheus Prometheus gathers metrics by scraping HTTP endpoints from specified targets. Below is a basic configuration for Prometheus in a file named prometheus.yml:

global:

scrape_interval: 15s # Default scrape interval

external_labels:

monitor: 'codelab-monitor'

scrape_configs:

• job_name: 'spring-boot-monitoring'

  scrape_interval: 5s # Override default interval

  metrics_path: '/actuator/prometheus'

  static_configs:

  • targets: ['spring-boot-api:8080']

    labels:

    application: 'demo spring boot monitoring'

By default, Prometheus looks for the prometheus.yml file in the current directory. This can be changed with the --config.file command line option.

#### Grafana: Provisioning the Data Source Grafana has built-in support for Prometheus. You can manage data sources by adding YAML configuration files in the provisioning/datasources directory. Each config can list datasources to add or update at startup. If a data source already exists, Grafana will adjust it to match the new configuration.

Here’s the YAML configuration for connecting Grafana to Prometheus:

apiVersion: 1

datasources:

• name: Prometheus

  type: prometheus

  access: proxy

  url: http://prometheus:9090

  isDefault: true # Set as default data source

Visualizing Data

Now, we can start all services using Docker. Here’s the complete Docker Compose configuration:

version: "3.8"

services:

prometheus:

image: prom/prometheus

container_name: prometheus

ports:

• "9090:9090"

volumes:

• ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml

networks:

• monitoring-network

grafana:

image: grafana/grafana

container_name: grafana

ports:

• "3000:3000"

volumes:

• ./grafana:/etc/grafana/provisioning/datasources

environment:

• GF_SECURITY_ADMIN_USER=admin
• GF_SECURITY_ADMIN_PASSWORD=admin

networks:

• monitoring-network

api:

image: spring-boot-monitoring

container_name: spring-boot-api

ports:

• "8080:8080"

restart: unless-stopped

networks:

• monitoring-network

networks:

monitoring-network:

To launch the services, run the following command:

docker compose up -d

You can access Prometheus at http://localhost:9090 and Grafana at http://localhost:3000.

> Explore Prometheus

> Explore Grafana The default username and password are `admin`, as specified in the Docker Compose file. You can reset the password upon your first login.

We have already configured Prometheus as a data source. Navigate to Connections > Data sources in Grafana.

You can create your own dashboard or choose from the Grafana marketplace. For this guide, we used the following dashboards: - https://grafana.com/grafana/dashboards/12835-spring-boot-statistics-6756-tomcat/ - https://grafana.com/grafana/dashboards/15104-jvm-overview/