Querying Metrics from Prometheus

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.
Install the Prometheus Addon.
Deploy the Bookinfo application.

Querying Istio metrics

Verify that the prometheus service is running in your cluster.

In Kubernetes environments, execute the following command:

$ kubectl -n istio-system get svc prometheus
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
prometheus   ClusterIP   10.109.160.254   <none>        9090/TCP   4m

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 example.
Open the Prometheus UI.

In Kubernetes environments, execute the following command:
```
$ istioctl dashboard prometheus
```
Click Graph to the right of Prometheus in the header.
Execute a Prometheus query.

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

The results will be similar to:

You can also see the query results graphically by selecting the Graph tab underneath the Execute button.

Other queries to try:

Total count of all requests to the productpage service:

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

Total count of all requests to v3 of the reviews service:
```
istio_requests_total{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 instances of the productpage service:

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

About the Prometheus addon

The Prometheus addon is a Prometheus server that comes preconfigured to scrape Istio endpoints to collect metrics. It provides a mechanism for persistent storage and querying of Istio metrics.

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

Cleanup

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