This example shows how the library can be used to both gather metrics based on metric specs.
In this example a deployment called php-apache is created with 4 replicas that responds to simple HTTP requests
with an OK!. The example will query the CPU metrics for the pods in this deployment and print them to stdout.
Note this example uses out of cluster configuration of the Kubernetes client, if you want to run this inside the cluster you should use in cluster configuration.
To follow the steps below and to see this example in action you need the following installed:
After you have installed the above you can provision a development Kubernetes cluster by running:
k3d cluster createRun go get to make sure you have all of the dependencies for running the application installed.
- First create the deployment to monitor by applying the deployment YAML:
kubectl apply -f deploy.yaml- Run the example using:
go run main.go- If you see some errors like this:
2022/05/08 22:26:09 invalid metrics (1 invalid out of 1), first error is: failed to get resource metric: unable to get metrics for resource cpu: no metrics returned from resource metrics API
Leave it for a minute or two to let the deployment being targeted (php-apache) to generate some CPU metrics with
the metrics server.
Eventually it should provide output like this:
2022/05/08 22:27:39 CPU statistics:
2022/05/08 22:27:39 Pod: php-apache-d4cf67d68-s9w2g, CPU usage: 1m (0.50% of requested)
2022/05/08 22:27:39 Pod: php-apache-d4cf67d68-v9fc2, CPU usage: 1m (0.50% of requested)
2022/05/08 22:27:39 Pod: php-apache-d4cf67d68-h4z4k, CPU usage: 1m (0.50% of requested)
2022/05/08 22:27:39 Pod: php-apache-d4cf67d68-jrskj, CPU usage: 1m (0.50% of requested)
2022/05/08 22:27:39 ----------
- Try increasing the CPU load:
kubectl run -it --rm load-generator --image=busybox -- /bin/shOnce it has loaded, run this command to increase CPU load:
while true; do wget -q -O- http://php-apache.default.svc.cluster.local; done