# metrics-server

From version 1.8 onwards, Kubernetes provides resource usage metrics, such as the container CPU and memory usage, through the Metrics API. These metrics can be directly accessed by users (for example, by using the kubectl top command) or used by controllers (for example, Horizontal Pod Autoscaler) in a cluster for decision-making. The specific component is metrics-server, which is used to substitute for heapster for providing the similar functions. heapster has been gradually abandoned since v1.11.

metrics-server is an aggregator for monitoring data of core cluster resources. You can quickly install this add-on on the CCE console.

After metrics-server is installed, you can create an HPA policy on the Workload Scaling tab page of the Auto Scaling page. For details, see Creating an HPA Policy for Workload Auto Scaling.

The official community project and documentation are available at https://github.com/kubernetes-sigs/metrics-server.

#### Notes and Constraints

This add-on can be installed only in CCE clusters of v1.13 or later.

#### Installing the Add-on

1. Log in to the CCE console. In the navigation pane, choose Add-ons. On the Add-on Marketplace tab page, click Install Add-on under metrics-server.
2. On the Install Add-on page, select the cluster and the add-on version, and click Next: Configuration.
3. Select Single or HA for Add-on Specifications, and click Install.

   After the add-on is installed, click Go Back to Previous Page. On the Add-on Instance tab page, select the corresponding cluster to view the running instance. This indicates that the add-on has been installed on each node in the cluster.

#### Upgrading the Add-on

1. Log in to the CCE console. In the navigation pane, choose Add-ons. On the Add-on Instance tab page, click Upgrade under metrics-server.

   - If the Upgrade button is not available, the current add-on is already up-to-date and no upgrade is required.
   - During the upgrade, the metrics-server add-on of the original version on cluster nodes will be discarded, and the add-on of the target version will be installed.
2. On the Basic Information page, select the add-on version and click Next.
3. Set the parameters by referring to the parameter description in Installing the Add-on and click Upgrade.

#### Uninstalling the Add-on

1. Log in to the CCE console. In the navigation pane, choose Add-ons. On the Add-on Instance tab page, click Uninstall under metrics-server.
2. In the dialog box displayed, click Yes to uninstall the add-on.

Parent topic: Add-ons