n3v3rf411 / go-prometheus-client-example

Sample on querying metrics from prometheus

Go Prometheus Client Example

This is an example of a web app that queries a Prometheus server. Originally intended as a proof-of-concept for querying the Prometheus server in the using Rancher's cluster monitoring, this can also be applied to other Prometheus instances that optionally have basic authentication.

The web app uses Echo.

Getting Started

For development, using dotenv is recommended for configuration. In production, this can be replaced with docker-compose environment or kubernetes config map.

cp .env.example .env

• PROMETHEUS_URL: Prometheus URL
• PROMETHEUS_AUTH_USERNAME: Optional basic auth username
• PROMETHEUS_AUTH_PASSWORD: Optional basic auth password

The project comes with basic support for docker container development and deployment. This is optional.

cd docker
cp .env.example .env
docker-compose up -d

Reflex will automatically reload the server if there are changes in .go or .html files.

Rancher Cluster Monitoring

A step-by-step guide can be found at https://hellowillie.com/2020/01/17/sample-go-web-app-for-querying-rancher-cluster-monitoring-prometheus/

To query the Prometheus instance deployed with Rancher's cluster monitoring:

• Deploy monitoring on a cluster
• Create a user role having the following grants on kubernetes resources: Create, Get, List, Watch on Resources services,services/proxy,endpoints (Custom), API Groups *
• Grant the created role on a user
• Generate an API for the user
• Obtain the Prometheus URL. This can be acquired by going to the Prometheus web interface. Example URL: http://rancher.local/k8s/clusters/c-pw2r2/api/v1/namespaces/cattle-prometheus/services/http:access-prometheus:80/proxy

License

This project is licensed under the MIT License - see the LICENSE file for details.