berndbausch/devstack-kubernetes

Making Devstack ready for running Kubernetes clusters

Running a Kubernetes cluster on Devstack

Devstack is a simple OpenStack deployment tool. Its main purpose is setting up testing platforms in OpenStack's CI environment, but it is also very popular as a comparatively simple method for creating proof-of-concept clouds, or clouds for experimenting with OpenStack. Devstack can create comparatively lean clouds that don't require tens of gigabytes of RAM and storage.

This repo is a collection of instructions, scripts and configuration files for creating a single-server Devstack cloud that demonstrates Kubernetes clusters on OpenStack.

It covers two methods of deploying a cluster: Manual via kubeadm, and semiautomatic via OpenStack Magnum. Apart from the standard OpenStack services, it deploys OpenStack's loadbalancer service Octavia, the Kubernetes cluster manager Magnum, and the Octavia and Magnum GUIs. By default, Devstack clouds use an isolated network, and Devstack servers are not meant to be rebooted. These instructions connect the cloud to the external network in your home or lab and include a script that permits rebooting the server.

The instructions are structured as follows:

1. Setting up Devstack
2. Creating a Kubernetes cluster with OpenStack cloud provider and the CSI Cinder plugin
3. Deploying a load-balanced application with Cinder volumes on the cluster
4. Creating a Kubernetes cluster using the OpenStack Magnum service
5. Deploying an application on the Magnum-managed Kubernetes cluster

The first three steps are based on the official K8s OpenStack cloud provider documentation and a blog entry on kubernetes.io that covers K8s-OpenStack integration.

Instructions, configurations and manifests were tested on a moderately sized Devstack server running Ubuntu 18.04, with 15GB of RAM and six virtual CPUs. It should be feasible on less RAM (12GB perhaps?), and half the CPUs should not be a problem.