Querying Metrics from Prometheus

This task shows you how to query for Istio Metrics using Prometheus. As part of this task, you will use the web-based interface for querying metric values.

The Bookinfo sample application is used as the example application throughout this task.

Before you begin

Install Istio in your cluster and deploy an application.

Querying Istio Metrics

Verify that the prometheus service is running in your cluster (since 0.8 the prometheus setup is included in istio-demo.yaml and istio-demo-auth.yaml by default)

In Kubernetes environments, execute the following command:
```
$ kubectl -n istio-system get svc prometheus
NAME         CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
prometheus   10.59.241.54   <none>        9090/TCP   2m
```
Send traffic to the mesh.

For the Bookinfo sample, visit http://$GATEWAY_URL/productpage in your web browser or issue the following command:
```
$ curl http://$GATEWAY_URL/productpage
```
$GATEWAY_URL is the value set in the Bookinfo guide.

Open the Prometheus UI.

In Kubernetes environments, execute the following command:

$ kubectl -n istio-system port-forward $(kubectl -n istio-system get pod -l app=prometheus -o jsonpath='{.items[0].metadata.name}') 9090:9090 &

Visit http://localhost:9090/graph in your web browser.

Execute a Prometheus query.

In the “Expression” input box at the top of the web page, enter the text: istio_request_count. Then, click the Execute button.

The results will be similar to:

Other queries to try:

Total count of all requests to productpage service:

istio_request_count{destination_service="productpage.default.svc.cluster.local"}

Total count of all requests to v3 of the reviews service:
```
istio_request_count{destination_service="reviews.default.svc.cluster.local", destination_version="v3"}
```
This query returns the current total count of all requests to the v3 of the reviews service.

Rate of requests over the past 5 minutes to all productpage services:

rate(istio_request_count{destination_service=~"productpage.*", response_code="200"}[5m])

About the Prometheus add-on

Mixer comes with a built-in Prometheus adapter that exposes an endpoint serving generated metric values. The Prometheus add-on is a Prometheus server that comes preconfigured to scrape Mixer endpoints to collect the exposed metrics. It provides a mechanism for persistent storage and querying of Istio metrics.

The configured Prometheus add-on scrapes three endpoints:

istio-mesh (istio-mixer.istio-system:42422): all Mixer-generated mesh metrics.
mixer (istio-mixer.istio-system:9093): all Mixer-specific metrics. Used to monitor Mixer itself.
envoy (istio-mixer.istio-system:9102): raw stats generated by Envoy (and translated from statsd to prometheus).

For more on querying Prometheus, please read their querying docs.

Cleanup

Remove any kubectl port-forward processes that may still be running:
```
$ killall kubectl
```
If you are not planning to explore any follow-on tasks, refer to the Bookinfo cleanup instructions to shutdown the application.

What's next

Refer to the In-Depth Telemetry guide.