Prometheus Stack Operator: Not Scraping Metrics for Your App? Here's a Small Demo to Help
In the world of monitoring and observability, Prometheus is a popular open-source tool that helps you collect and query time series data. To make the deployment and management of Prometheus easier, the Prometheus Stack Operator is available, which simplifies the process of creating and managing Prometheus configurations and rules.
Collecting Metrics Cluster for Your Application
To start collecting metrics for your application, you first need to install and set up the Prometheus Stack Operator in your Kubernetes cluster. Once you have done that, you can create a new Prometheus installation targeting your application's pods.
Installing Helm and the kube-prometheus-stack
Helm is a package manager for Kubernetes that makes it easy to install and manage applications in your cluster. To install Helm, follow the instructions on the official Helm website. Once Helm is installed, you can install the kube-prometheus-stack, which includes the Prometheus Operator and Prometheus components, using the following command:
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm install my-prometheus prometheus-community/kube-prometheus-stack
Creating a ServiceMonitor for Your Application
To start scraping metrics for your application, you need to create a ServiceMonitor resource that targets your application's Service. The ServiceMonitor defines the properties of the Service that should be monitored and the Prometheus instance that should be used for scraping.
Here's a demo of a ServiceMonitor that targets a sample application:
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
name: my-app-monitor
spec:
selector:
matchLabels:
app: my-app
endpoints:
- port: http
path: /metrics
Verifying the Metrics are Being Scraped
To verify that the metrics are being scraped, you can check the Prometheus server to see if the metrics from your application are present. To do this, you can use the Prometheus query language (PromQL) to query for the metrics from your application. For example, the following PromQL query would return the HTTP request duration for requests to the `/health` endpoint of your application:
http_request_duration_seconds{path="/health"}
Troubleshooting Common Issues
If you find that the metrics are not being scraped, there are a few common issues to check:
-
ServiceMatchLabelNotSet: Make sure that the ServiceMonitor selector matches the labels on the targeted Service.
-
EndpointNotExposed: Check that the endpoint defined in the ServiceMonitor is exposed and accessible to the Prometheus pods.
-
ServiceMonitorNotCreated: Check that the ServiceMonitor is actually being created by the Prometheus Operator.
The Prometheus Stack Operator is a powerful tool for simplifying the process of deploying and managing Prometheus in your Kubernetes cluster. By creating a ServiceMonitor resource for your application, you can easily start collecting metrics for your application. If you find that the metrics are not being scraped, check for common issues such as ServiceMatchLabelNotSet, EndpointNotExposed, and ServiceMonitorNotCreated.
References
-
Prometheus Operator: https://github.com/prometheus-operator/prometheus-operator
-
Prometheus: https://prometheus.io/
-
Helm: https://helm.sh/
-
kube-prometheus-stack: https://github.com/prometheus-community/helm-charts/tree/main/charts/kube-prometheus-stack