How to Deploy Prometheus on Kubernetes

In this tutorial, we’ll discuss how to set up Prometheus on Kubernetes. We’ll assume that you’ve already installed Helm and K3s. If you don’t have K3s and Helm installed you can follow our guide. Prometheus has established itself as a top open-source option for monitoring and alerting systems. It is renowned for its multi-dimensional data model with time series data identified by metric name and key/value pairs, flexible query language, and integration with many well-liked graphing and dashboarding solutions.

Introduction

Due to its powerful features and usability, Prometheus has established itself as a go-to solution for many organizations. You can build a strong platform for monitoring your applications and systems by combining it with K3s, a Kubernetes distribution that is incredibly effective and streamlined.

Getting Your Environment Ready

It’s important to confirm that your environment is properly configured before we start the installation process of Prometheus on Kubernetes. We won’t do K3s and Helm installation because we’ll assume that they are already installed.

You must ensure that Helm is installed and updated to the most recent version and that the K3s cluster is operational. Run kubectl get nodes to verify the K3s cluster, and helm version to verify Helm.

Deploy Prometheus on Kubernetes

The Prometheus Operator is an open-source project that enables quick monitoring definitions for Kubernetes services as well as the deployment and administration of Prometheus instances.

First, add the Prometheus community Helm charts by executing the following command:

helm repo add prometheus-community https://prometheus-community.github.io/helm-charts

Next, update the Helm repository:

helm repo update

Now, create a namespace for Prometheus:

kubectl create namespace prometheus

Finally, install the Prometheus Operator:

helm install prometheus prometheus-community/kube-prometheus-stack --namespace prometheus

This command will install the Prometheus Operator in the ‘prometheus’ namespace.

Create a Prometheus Configuration File

To specify your Prometheus on Kubernetes instance, Service, and ServiceMonitor, you must create a configuration file (prometheus.yaml). Here is an easy illustration:

apiVersion: monitoring.coreos.com/v1
kind: Prometheus
metadata:
  name: prometheus
  namespace: prometheus
spec:
  serviceAccountName: prometheus
  serviceMonitorSelector:
    matchLabels:
      team: frontend
  resources:
    requests:
      memory: 400Mi
  enableAdminAPI: false
---
apiVersion: v1
kind: Service
metadata:
  name: prometheus
  namespace: prometheus
spec:
  selector:
    prometheus: prometheus
  type: NodePort
  ports:
    - name: web
      port: 9090
      targetPort: web
      nodePort: 30900
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: k3s
  labels:
    team: frontend
spec:
  selector:
    matchLabels:
      app: k3s
  endpoints:
  - port: web
    interval: 15s

Use kubectl to apply the configuration file and deploy Prometheus on Kubernetes:

kubectl apply -f prometheus.yaml -n prometheus

This command will deploy Prometheus in the ‘prometheus’ namespace using the configuration specified in the prometheus.yaml file.

Once Prometheus is deployed, you can access it by using the kubectl port-forward command:

kubectl port-forward svc/prometheus 9090:9090 -n prometheus

Then, open your web browser and navigate to http://localhost:9090.

Configuring Prometheus on Kubernetes

You must set up the Prometheus Operator to monitor your K3s cluster after installation. In order to monitor Kubernetes services, the Prometheus Operator provides a custom resource called a ServiceMonitor, which you will create to accomplish this.

Here is a sample ServiceMonitor configuration:

apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: k3s
  labels:
    release: prometheus
spec:
  selector:
    matchLabels:
      k8s-app: kube-state-metrics
  namespaceSelector:
    matchNames:
      - kube-system
  endpoints:
  - port: http-metrics
    interval: 30s

Save this configuration to a file named ‘servicemonitor.yaml’, then apply it with kubectl apply -f servicemonitor.yaml -n prometheus.

Verifying the Deployment

Once Prometheus has been installed, you should make sure it is functioning properly. To begin with, make sure the Prometheus pods are operational:

kubectl get pods -n prometheus

You should see the Prometheus pods listed. Next, check that the Prometheus service is running:

kubectl get service -n prometheus

Monitoring Your K3s Cluster

You can use Prometheus to monitor your K3s cluster now that it has been installed and is operational. Grafana, which is part of the kube-prometheus-stack Helm chart, allows you to create alerting rules, query your time-series data, and visualize your data.

Final Thoughts

In this guide, we walked you through the process of deploying Prometheus on Kubernetes cluster using Helm. Although the process may seem complicated at first, it becomes straightforward once you understand the steps involved. By deploying Prometheus on K3s, you can leverage a powerful and flexible monitoring solution that can help you keep a close eye on your applications and systems.