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edit instructions for hpa based on custom metrics

reviewable/pr4644/r1
Jessica Yao 2017-08-02 17:20:49 -07:00 committed by Andrew Chen
parent 8be19e168a
commit 59349b8bdc
1 changed files with 20 additions and 10 deletions
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docs/tasks/run-application/horizontal-pod-autoscale.md
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@ -123,18 +123,28 @@ Kubernetes 1.6 adds support for making use of custom metrics in the Horizontal P
You can add custom metrics for the Horizontal Pod Autoscaler to use in the `autoscaling/v2alpha1` API. You can add custom metrics for the Horizontal Pod Autoscaler to use in the `autoscaling/v2alpha1` API.
Kubernetes then queries the new custom metrics API to fetch the values of the appropriate custom metrics. Kubernetes then queries the new custom metrics API to fetch the values of the appropriate custom metrics.
### Prerequisites ### Requirements
In order to use custom metrics in the Horizontal Pod Autoscaler, you must deploy your cluster with the To use custom metrics with your Horizontal Pod Autoscaler, you must set the necessary configurations when deploying your cluster:
`--horizontal-pod-autoscaler-use-rest-clients` flag on the controller manager set to true. You must then configure
your controller manager to speak to the API server through the API server aggregator, by setting the controller
manager's target API server to the API server aggregator (using the `--apiserver` flag). The resource metrics API and
custom metrics API must also be registered with the API server aggregator, and must be served by API servers running
on the cluster.
You can use Heapster's implementation of the resource metrics API by running Heapster with the`--api-server` flag set * [Enable the API aggregation layer](/docs/tasks/access-kubernetes-api/configure-aggregation-layer/) if you have not already done so.
to true. A separate component must provide the custom metrics API (more information on the custom metrics API is
available at [the k8s.io/metrics repository](https://github.com/kubernetes/metrics)). * Register your resource metrics API and your
custom metrics API with the API aggregation layer. Both of these API servers must be running *on* your cluster.
* *Resource Metrics API*: You can use Heapster's implementation of the resource metrics API, by running Heapster with its `--api-server` flag set to true.
* *Custom Metrics API*: This must be provided by a separate component. To get started with boilerplate code, see the [kubernetes-incubator/custom-metrics-apiserver](https://github.com/kubernetes-incubator/custom-metrics-apiserver) and the [k8s.io/metrics](https://github.com/kubernetes/metrics) repositories.
* Set the appropriate flags for kube-controller-manager:
* `--horizontal-pod-autoscaler-use-rest-clients` should be true.
* `--kubeconfig <path-to-kubeconfig>` OR `--master <ip-address-of-apiserver>`
Note that either the `--master` or `--kubeconfig` flag can be used; `--master` will override `--kubeconfig` if both are specified. These flags specify the location of the API aggregation layer, allowing the controller manager to communicate to the API server.
In Kubernetes 1.7, the standard aggregation layer that Kubernetes provides runs in-process with the kube-apiserver, so the target IP address can be found with `kubectl get pods --selector k8s-app=kube-apiserver --namespace kube-system -o jsonpath='{.items[0].status.podIP}'`.
## Further reading ## Further reading