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Updated doc for cluster autoscaler

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Marcin Wielgus
2015-10-07 10:57:07 +02:00
parent bc61bcc1ad
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docs/admin/cluster-management.md
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@@ -118,16 +118,19 @@ In other environments you may need to configure the machine yourself and tell th
### Horizontal auto-scaling of nodes (GCE)
If you are using GCE, you can configure your cluster so that the number of nodes will be automatically scaled based on their CPU and memory utilization.
If you are using GCE, you can configure your cluster so that the number of nodes will be automatically scaled based on:
* CPU and memory utilization.
* Amount of of CPU and memory requested by the pods (called also reservation).
Before setting up the cluster by ```kube-up.sh```, you can set ```KUBE_ENABLE_NODE_AUTOSCALER``` environment variable to ```true``` and export it.
The script will create an autoscaler for the instance group managing your nodes.
The autoscaler will try to maintain the average CPU and memory utilization of nodes within the cluster close to the target value.
The autoscaler will try to maintain the average CPU/memory utilization and reservation of nodes within the cluster close to the target value.
The target value can be configured by ```KUBE_TARGET_NODE_UTILIZATION``` environment variable (default: 0.7) for ``kube-up.sh`` when creating the cluster.
The node utilization is the total node's CPU/memory usage (OS + k8s + user load) divided by the node's capacity.
If the desired numbers of nodes in the cluster resulting from CPU utilization and memory utilization are different,
the autoscaler will choose the bigger number.
The number of nodes in the cluster set by the autoscaler will be limited from ```KUBE_AUTOSCALER_MIN_NODES``` (default: 1)
Node utilization is the total node's CPU/memory usage (OS + k8s + user load) divided by the node's capacity.
Node reservation is the total CPU/memory requested by pods that are running on the node divided by the node's capacity.
If the desired numbers of nodes in the cluster resulting from CPU/memory utilization/reservation are different,
the autoscaler will choose the bigger number. The number of nodes in the cluster set by the autoscaler will be limited from ```KUBE_AUTOSCALER_MIN_NODES``` (default: 1)
to ```KUBE_AUTOSCALER_MAX_NODES``` (default: the initial number of nodes in the cluster).
The autoscaler is implemented as a Compute Engine Autoscaler.
@@ -141,7 +144,8 @@ gcloud preview autoscaler --zone compute-zone <command>
Note that autoscaling will work properly only if node metrics are accessible in Google Cloud Monitoring.
To make the metrics accessible, you need to create your cluster with ```KUBE_ENABLE_CLUSTER_MONITORING```
equal to ```google``` or ```googleinfluxdb``` (```googleinfluxdb``` is the default value).
equal to ```google``` or ```googleinfluxdb``` (```googleinfluxdb``` is the default value). Please also make sure
that you have Google Cloud Monitoring API enabled in Google Developer Console.
## Maintenance on a Node