Monitoring Spring Cloud Gateway with Prometheus and Grafana

This is a little proof-of-concept I wrote for monitoring a Spring Cloud Gateway with Prometheus and Grafana.

Feel free to copy this or use it as a blueprint to build anything you like. I've used docker-compose to make this a smother experience to demo.
It is not at all production ready and you should not treat it as such.

About

The entire thing is really quite simple.

• The Spring Cloud Gateway collects metrics and exposes them under /actuator/prometheus
• Prometheus collects to metrics and safes them in its database
• Grafana gets its metrics from Prometheus and displays them in fancy graphs. Or sends alerts. Or does do other stuff.

Custom metrics

All the custom metrics are collected in this class. They are really nothing fancy and just count up everytime a request is made or an response is received. In fact the default metrics already implement this function but I thought it is a good example anyway. So I did it again.

Trying it yourself

If you want to try it yourself just clone this repo and replicate the steps below.

Prerequisites

To run this application you need:

• docker
• docker-compose
• JDK 17 or later
• the ability to build this maven project

Run the application

Build the maven project

mvn clean package

Run docker-compose

docker-compose up

If you execute docker ps you should now see three containers running (some things will differ though)

CONTAINER ID   IMAGE                         COMMAND                  CREATED        STATUS       PORTS                                       NAMES
76c2da3da29c   prom/prometheus:latest        "/bin/prometheus --w…"   2 hours ago    Up 2 hours   0.0.0.0:9090->9090/tcp, :::9090->9090/tcp   spring-cloud-gateway-monitoring-prometheus-1
37bb0b105e27   grafana/grafana:latest        "/run.sh"                2 hours ago    Up 2 hours   0.0.0.0:3000->3000/tcp, :::3000->3000/tcp   spring-cloud-gateway-monitoring-grafana-1
90db75229a20   spring-cloud-gateway:latest   "java -jar /app.jar"     43 hours ago   Up 2 hours   0.0.0.0:8080->8080/tcp, :::8080->8080/tcp   spring-cloud-gateway-monitoring-spring-cloud-gateway-1

Also if you open http://localhost:9090/targets?search= you should see that Prometheus can connect to your gateway and receive its metrics.

If you want to 'simulate' traffic, run the example-traffic script. It is just a glorified while-loop, but it does the job.

bash ./example-traffic

Looking at all those pretty graphs

To see all the data in Grafana you have to log in and create some dashboards first.

Go to http://localhost:3000 and log in with the user admin and the password admin. In the sidebar you can import dashboards. See here for a tutorial.
Be sure to choose 'Prometheus' as a datasource for all your dashboards.

A good one for Spring Boot is this one with the id 12900 by prakarsh.

It should look something like this:

Experiencing issues?

If you've got any issues feel free to create an issue. I respond if I can.

Credits

Credit where credit is due

• Creating the docker-compose file for Grafana and Prometheus
• Spring Boot dashboard for Grafana