# Overview

The _kubespawner_ (also known as JupyterHub Kubernetes Spawner) enables JupyterHub to spawn single-user notebook servers on a [Kubernetes](https://kubernetes.io/) cluster.

## Features

Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications. If you want to run a JupyterHub setup that needs to scale across multiple nodes (anything with over ~50 simultaneous users), Kubernetes is a wonderful way to do it. Features include:

  • Easily and elasticly run anywhere between 2 and thousands of nodes with the same set of powerful abstractions. Scale up and down as required by simply adding or removing nodes.

  • Run JupyterHub itself inside Kubernetes easily. This allows you to manage many JupyterHub deployments with only Kubernetes, without requiring an extra layer of Ansible / Puppet / Bash scripts. This also provides easy integrated monitoring and failover for the hub process itself.

  • Spawn multiple hubs in the same kubernetes cluster, with support for [namespaces](https://kubernetes.io/docs/tasks/administer-cluster/namespaces/). You can limit the amount of resources each namespace can use, effectively limiting the amount of resources a single JupyterHub (and its users) can use. This allows organizations to easily maintain multiple JupyterHubs with just one kubernetes cluster, allowing for easy maintenance & high resource utilization.

  • Provide guarantees and limits on the amount of resources (CPU / RAM) that single-user notebooks can use. Kubernetes has comprehensive [resource control](https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/) that can be used from the spawner.

  • Mount various types of [persistent volumes](https://kubernetes.io/docs/concepts/storage/persistent-volumes/) onto the single-user notebook’s container.

  • Control various security parameters (such as userid/groupid, SELinux, etc) via flexible [Pod Security Policies](https://kubernetes.io/docs/concepts/policy/pod-security-policy/).

  • Run easily in multiple clouds (or on your own machines). Helps avoid vendor lock-in. You can even spread out your cluster across [multiple clouds at the same time](https://kubernetes.io/docs/concepts/cluster-administration/federation/).

  • Internal SSL configuration supported

In general, Kubernetes provides a ton of well thought out, useful features - and you can use all of them along with this spawner.

## Requirements

### Kubernetes

Everything should work from Kubernetes v1.6+.

The [Kube DNS addon](https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/#dns) is not strictly required - the spawner uses [environment variable](https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/#environment-variables) based discovery instead. Your kubernetes cluster will need to be configured to support the types of volumes you want to use.

If you are just getting started and want a kubernetes cluster to play with, [Google Container Engine](https://cloud.google.com/kubernetes-engine/) is probably the nicest option. For AWS/Azure, [kops](https://github.com/kubernetes/kops) is probably the way to go.