What is Prometheus?
- Docker & Kubernetes course
- Advanced
- Lesson 49/70
- 4 min
Learn Prometheus as a metrics collection system.
What is Prometheus?
Prometheus is an open-source monitoring system that collects and stores time-series metrics. It works with a pull model: it reads the targets' /metrics endpoint at intervals (scrape). Metrics are identified by name and labels:
$ curl -s http://api:8000/metrics | head -4
# HELP http_requests_total Toplam HTTP istekleri
# TYPE http_requests_total counter
http_requests_total{method="GET",path="/urunler",status="200"} 10432
http_requests_total{method="POST",path="/sepet",status="500"} 17In Kubernetes, the most common installation is the kube-prometheus-stack Helm chart: Prometheus, Alertmanager, Grafana and ready dashboards.
Metric types
- Counter: a counter that only goes up (total requests, errors). Used with
rate()for speed. - Gauge: a value that goes up and down (memory, queue length).
- Histogram: the distribution of values in buckets (response time); percentiles are calculated.
- Summary: percentiles calculated on the client side.
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm install izleme prometheus-community/kube-prometheus-stack -n izleme --create-namespace
kubectl port-forward -n izleme svc/izleme-kube-prometheus-sta-prometheus 9090Practice Install Prometheus
Write three commands: add the prometheus-community repository with the address https://prometheus-community.github.io/helm-charts; install the prometheus-community/kube-prometheus-stack chart with the release name izleme into the izleme namespace (creating it if missing); list the pods in izleme.
Starter code
# buraya yazSample solution
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm install izleme prometheus-community/kube-prometheus-stack -n izleme --create-namespace
kubectl get pods -n izlemeExpected output
"prometheus-community" has been added to your repositories NAME: izleme STATUS: deployed NAME READY STATUS RESTARTS AGE alertmanager-izleme-kube-prometheus-sta-alertmanager-0 2/2 Running 0 60s izleme-grafana-6c8d9b7f4-x2k9p 3/3 Running 0 65s prometheus-izleme-kube-prometheus-sta-prometheus-0 2/2 Running 0 60s
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How does Prometheus collect metrics?
- By reading log files
- From etcd
- By pulling the targets' /metrics endpoint at intervals Correct answer
- Applications push to it
Explanation: There is a Pushgateway intermediary for short-lived jobs.
2 Write the target's metrics endpoint.
curl -s http://api:8000/____curl -s http://api:8000/metricsExplanation: Prometheus conventionally reads /metrics.
3 Match the types.
| Term | Meaning |
|---|---|
Counter |
Only goes up |
Gauge |
Goes up and down |
Histogram |
Bucketed distribution |
scrape |
Pulling |