Brightbox Kubernetes Clusters now Autoscale from Zero

Since the last post on how the Kubernetes Autoscaler works on Brightbox we’ve been hard at work improving it.

Scaling From Zero

Whereas previously there had to be at least one worker server in each worker group, we’ve now added the ability to go down to zero.

This means you can set up a Kubernetes cluster with nothing but the control plane servers in place and let the autoscaler build and deploy worker nodes as required.

The facility is available in the latest Brightbox autoscaler releases for Kubernetes 1.18 and above

What’s Changed in Brightbox Autoscaler

When the autoscaler wants to scale up it used to look at the other servers in the group to use as a template but now groups can have zero servers, so what do we do?

We extended the Brightbox API and added a Config Map resource inspired by the corresponding resource within a Kubernetes cluster.

Now when the autoscaler wants to expand a group it will look for a Config Map corresponding to the cluster name (e.g. k8s-worker.k8s-test.cluster.local) which contains all the details required to build a server.

The data item of a Config Map is a simple JSON object with the following keys:

• min: the lowest number of nodes to maintain in the group
• max: the largest number of nodes there should be in the group
• image: the id of the image to build new nodes with
• type: the id of server type to use for each node
• region: which region to build the node in
• zone: the id of the zone to build the node in
• user_data: the userdata to use with each node - and which should bootstrap Kubernetes
• server_group: the id of the worker server group
• default_group: the id of the cluster overall server group

Cluster configuration

Of course our Kubernetes Cluster Builder terraform manifests will manage the Config Map for you. Just set the worker_max values to scale the worker group, and the storage_max values to scale the storage group. You can now leave worker_count and even storage_count at zero if you wish.

Try Brightbox for free

If you want to play with Kubernetes, you can sign up for Brightbox Cloud real quick and use your £50 free credit to give it a go.

Managed Kubernetes services

If instead you want us to run Kubernetes for you, or anything else for that matter, we offer hands-on support and managed services too. Drop us a line.