What is Prometheus? As per the official documentation, Prometheus is an open source system monitoring tool kit based on a time series database. It measures values at a periodic occurrence of time. It was founded at Sound Cloud in the year 2012, but is a standalone open source project and maintained independently of any single company. It was adopted by CNCF in 2016.
What is Prometheus?
Prometheus is a pull-based monitoring system. Take a look at the above reference architecture. It can be designed to monitor servers, virtual machines, databases, etc. We know it is crucial to monitor these resources periodically. It relies on HTTP calls. For example: If a web server is hosted at
http://foo-bar:8080, and exposes metrics at
http://foo-bar:8080/metrics, Prometheus pulls the data from the target URL. The most important point to note here is that Prometheus is not an event-based monitoring system, meaning it does not send alerts. Instead, it collects pre-determined metrics about your applications based on rules.
From the diagram, we see that Prometheus collects metrics from pre-configured services or applications and then stores it on a storage disk. The collected data is pushed to its alert management system. From there, it is retrieved for pager use, email, or any other methods.
Data visualization: As seen in the above diagram, you can visualize a target's data using the Prometheus web-ui. It also has a filtering system that allows the user to view custom metrics.
Getting my hands dirty with Prometheus
So, there are two options for getting started with Prometheus:
- Make use of this scenario using Katakoda.
- Follow along by installing minikube on a CentOS 8 machine.
Since it's a hands-on blogpost, I focus on the second method and leave the first method to curious readers.
minikube is up and running:
helm by following the steps below. If you want to brush up on
helm basics, please refer to the official help.
$ curl -fsSL -o get_helm.sh https://raw.githubusercontent.com/helm/helm/master/scripts/get-helm-3 $ chmod 700 get_helm.sh $ ./get_helm.sh
After you enable
helm, you just need to install Prometheus using this command:
[root@prometheus-server ~]# helm install prometheus stable/prometheus --namespace monitoring Error: failed to download "stable/prometheus" (hint: running `helm repo update` may help) [root@prometheus-server ~]# helm repo add stable https://kubernetes-charts.storage.googleapis.com/ "stable" has been added to your repositories [root@prometheus-server ~]# helm repo update Hang tight while we grab the latest from your chart repositories... ...Successfully got an update from the "stable" chart repository Update Complete. ⎈ Happy Helming!⎈ [root@prometheus-server ~]# helm install prometheus stable/prometheus --namespace default
Now we see that Prometheus is installed on
minikube. We list its service information with the following command:
[root@prometheus-server ~]# minikube service list |-------------|-------------------------------|--------------|-----| | NAMESPACE | NAME | TARGET PORT | URL | |-------------|-------------------------------|--------------|-----| | default | kubernetes | No node port | | default | prometheus-alertmanager | No node port | | default | prometheus-kube-state-metrics | No node port | | default | prometheus-node-exporter | No node port | | default | prometheus-pushgateway | No node port | | default | prometheus-server | No node port | | kube-system | kube-dns | No node port | | kube-system | metrics-server | No node port |
This article covers the basic concepts of Prometheus as well as installation on
minikube. I will cover applications monitoring in the next article, so be sure to keep an eye out for that.
- The Official Prometheus Website
- Prometheus Monitoring: The Definitive Guide
- How to Set Up Prometheus and Ingress on Kubernetes
[ Free cheat sheet: Kubernetes glossary ]