The Autoscaling applications using the Horizontal Pod Autoscaler recipe in this section also requires Metrics Server to be installed on your cluster. Metrics Server is a cluster-wide aggregator for core resource usage data. Follow these steps to validate the installation of Metrics Server:

1. Confirm if you need to install Metrics Server by running the following command:

$ kubectl top node
error: metrics not available yet

2. If it's been installed correctly, you should see the following node metrics:

$ kubectl top nodes
NAME                          CPU(cores) CPU% MEMORY(bytes) MEMORY%
ip-172-20-32-169.ec2.internal 259m       12%  1492Mi        19%
ip-172-20-37-106.ec2.internal 190m       9%   1450Mi        18%
ip-172-20-48-49.ec2.internal  262m       13%  2166Mi        27%
ip-172-20-58-155.ec2.internal 745m       37%  1130Mi        14%

If you get an error message stating metrics not available yet, then you need to follow the steps provided in the next chapter in the Adding metrics using the Kubernetes Metrics Server recipe to install Metrics Server.