45 lines
2.1 KiB
Markdown
45 lines
2.1 KiB
Markdown
---
|
|
approvers:
|
|
- fgrzadkowski
|
|
- piosz
|
|
title: Core metrics pipeline
|
|
---
|
|
|
|
Starting from Kubernetes 1.8, resource usage metrics, such as container CPU and memory usage,
|
|
are available in Kubernetes through the Metrics API. These metrics can be either accessed directly
|
|
by user, for example by using `kubectl top` command, or used by a controller in the cluster, e.g.
|
|
Horizontal Pod Autoscaler, to make decisions.
|
|
|
|
## The Metrics API
|
|
|
|
Through the Metrics API you can get the amount of resource currently used
|
|
by a given node or a given pod. This API doesn't store the metric values,
|
|
so it's not possible for example to get the amount of resources used by a
|
|
given node 10 minutes ago.
|
|
|
|
The API no different from any other API:
|
|
|
|
- it is discoverable through the same endpoint as the other Kubernetes APIs under `/apis/metrics.k8s.io/` path
|
|
- it offers the same security, scalability and reliability guarantees
|
|
|
|
The API is defined in [k8s.io/metrics](https://github.com/kubernetes/metrics/blob/master/pkg/apis/metrics/v1beta1/types.go)
|
|
repository. You can find more information about the API there.
|
|
|
|
**Note:** The API requires metrics server to be deployed in the cluster. Otherwise it will be not available.
|
|
|
|
## Metrics Server
|
|
|
|
[Metrics Server](https://github.com/kubernetes-incubator/metrics-server) is a cluster-wide aggregator of resource usage data.
|
|
Starting from Kubernetes 1.8 it's deployed by default in clusters created by `kube-up.sh` script
|
|
as a Deployment object. If you use a different Kubernetes setup mechanism you can deploy it using the provided
|
|
[deployment yamls](https://github.com/kubernetes-incubator/metrics-server/tree/master/deploy).
|
|
It's supported in Kubernetes 1.7+ (see details below).
|
|
|
|
Metric server collects metrics from the Summary API, exposed by [Kubelet](/docs/admin/kubelet/) on each node.
|
|
|
|
Metrics Server registered in the main API server through
|
|
[Kubernetes aggregator](https://kubernetes.io/docs/concepts/api-extension/apiserver-aggregation/),
|
|
which was introduced in Kubernetes 1.7.
|
|
|
|
Learn more about the metrics server in [the design doc](https://github.com/kubernetes/community/blob/master/contributors/design-proposals/instrumentation/metrics-server.md).
|