Rke: Node autoscaling

[jaxxstorm]

RKE version:
v0.1.14

Operating system and kernel: (cat /etc/os-release, uname -r preferred)
CoreOS

Type/provider of hosts: (VirtualBox/Bare-metal/AWS/GCE/DO)

AWS

Currently, it seems the only way to add nodes to a cluster is to update the cluster.yml and then reprovision.

Is there any way to add a single node at a time, for example, if an ASG scales up? I'd like to be able to just run RKE on a single node, and then connect it to an existing cluster, but there doesn't seem to be any way to do that.

[alena1108]

@jaxxstorm not in standalone RKE. But if you use Rancher (which uses rke internally) there is a host provisioning option called "Custom". When chose this option, Rancher generates the command that you can bake in to AWS cloud init script, so a new node added by ASG would get registered to the cluster automatically.

[jaxxstorm]

Can we have this added to RKE, or at least an example command?

[ajfriesen]

Would it be possible to do this on the basis of prometheus stats we get from the cluster?
When a value hits a certain threshold there will be an api call to rancher to spawn a node in specific cluster in a specific AZ.

[vikas027]

Hey @alena1108 ,

This sounds like a chicken-egg problem. In order to host a rancher cluster, I still need a running k8s cluster. It would be great if RKE could handle some kind of autoscaling.

[clouddistortion]

Hey @alena1108 ,

This sounds like a chicken-egg problem. In order to host a rancher cluster, I still need a running k8s cluster. It would be great if RKE could handle some kind of autoscaling.

indeed! If you develop a solution on how to (auto)scale your kubernetes cluster for running rancher e.g. with kops you already have a solution and don't really need rancher anymore for the scaling functionality

[aslafy-z]

Any news on this matter? We'd like to use RKE to provision our control planes nodes and then make the cluster-autoscaler component provision worker nodes (using a scale set - asg) for us.