metricstrait

README

KubeVela Metrics Trait

This trait is designed to provide an easy way for an OAM application operator to collect metrics from any workload that emits metrics through an endpoint reachable from within the cluster. The metrics traits relies on Prometheus operator and Prometheus helm chart.

Install

Make sure KubeVela is installed in your cluster

Install metrics trait controller with helm

1. Add helm chart repo for metrics trait

   helm repo add oam.catalog  http://oam.dev/catalog/
   

2. Update the chart repo

   helm repo update
   

3. Install metrics trait controller

   helm install --create-namespace -n vela-system metricstrait oam.catalog/metricstrait
   
   

4. Apply definition yaml in registry.

Setting metrics policy

With this trait, an application operator only needs to specify a few fields to extract metrics from the workloads the trait attached to. Here are the brief descriptions of each field and its usage.

Name	Optional	Default	Description
format	Yes	"prometheus"	The format of the data. The only format we support now is prometheus
port	Yes	N/A	The pod port that exposes the metrics data. We use this to locate either a service or a pod
selector	Yes	N/A	The selector that can be used to label select target pods. The default uses the labels on the workload.
path	Yes	"/metrics"	path to scrape for metrics from the end point.
scheme	Yes	"http"	The scrap scheme that we support. We only support http for now.
enabled	Yes	"true"	Switch for the trait to be turned on or off.

There are two major scenarios when the metrics trait work.

Collect metrics through an existing service

One is that the workload it associated with already has a service exposes the metrics endpoints. The workload owner has to use workloadDefinition to indicate that in its ChildResourceKinds fields. In this case, the trait controller uses the portName field to locate the matching service.
Here is an example metrics trait CR that will create a servcieMonitor object to collect metrics through the matching service. Please note that this means the portName needs to be unique among the services that expose the workload.

 apiVersion: standard.oam.dev/v1alpha1
 kind: MetricsTrait
 metadata:
   name: metricstrait-sample-with-service
 spec:
   scrapeService:
     portName: http

For details, please refer to an application example using deployment as a workload.

Collect metrics without an existing service

The metrics trait controller will create a service when the workload doesn't come with a service. It relies on the targetPort and targetSelector field to locate the pod and its port that exposes the metrics.
Here is an example metrics trait CR that will create a service to expose the pod port.

 apiVersion: standard.oam.dev/v1alpha1
 kind: MetricsTrait
 metadata:
   name: metricstrait-sample-without-service
 spec:
   scrapeService:
     format: "prometheus"
     targetPort: 8080
     targetSelector:
       app: sample-app
     path: "/anypath"
     scheme:  "http"
     enabled: true

For details, please refer to an application example using deployment as a workload.

License

By contributing to the OAM category repository, you agree that your contributions will be licensed under its Apache 2.0 License.