Playing with OpenShift (OKD)

OKD is the open source version of Red Hat's OpenShift. Previously OKD used to be called OpenShift Origin. OKD is a Platform As A Service solution and build on different component layers.

OKD combines together the following features (ref) :

• Docker Engine
• Kubernetes container orchestration
• Monitoring source code and build new docker images
• Deploy images
• Manage DNS and routing
• Load balancing and scaling up and down resources

Motivation

Kubernetes is a powerful tool but it has a deep learning curve. One of the main benefit of OKD, that it provides a user friendly graphical user interface. Using Kubernetes via OKD helps to setup deployment and continuous integration much faster, so we allocate more time for application development.

Getting started with OKD

We can install OKD on our development machine. We can use Minishift, a single-node OpenShift cluster management tool. Preferred way to install Minishift on macOS is using brew. (ref)

1. Setup hyperkit driver

brew install hyperkit
brew install docker-machine-driver-hyperkit

2. Install minishift with brew cask

brew cask install minishift

3. Create and launch OKD Cluster

minishift start --vm-driver hyperkit --disk-size 60GB --memory 6GB --cpus 4 --public-hostname cluster.local --network-nameserver 10.254.254.254

Notes for the step 3:

The terminal command above sets a custom public hostname. We have to add this hostname to /etc/hosts file. We need the IP address of the cluster also. The first time, the above process will exit, because it cannot find the host, however the cluster will be active. Run the following command.

$ minishift ip
192.168.64.2

The ip address could be different. Setup /etc/hosts.

192.168.64.2 cluster.local

Additionally the custom DNS resolver (dnsmasq) should be also adjusted on the developer machine. Add the following address resolver line to dnsmasq.conf.

address=/.cluster.local/192.168.64.2

Please note the --network-nameserver option set the host machine's localhost loopback alias address which is configured as a nameserver with dnsmasq.

Stop and start minishift

minishift stop
minishift start

Open web console in browser

minishift console

Default login details: developer/developer | system/admin

Alternative drivers

For running Docker on macOS need a virtualization layer. MacOS has a hypervisor framework which running directly on the kernel. There is a project called Hyperkit which provides a low level virtualization engine. If we use docker-machine-driver-hyperkit package as a driver for our docker-machine than we don't have to install any virtual machine, like VirtualBox or VMWare.

However, experimenting with hyperkit driver was not always reliable and consistent. For example, if the Mac was rebooted, the minishift start command was not able to launch the previously created environment.

Hyperkit driver predecessor is called xhyve. It is still supported by minishift. Experimenting with xhyve showed a more reliable environment. But launching the environment was still slow.

Launching minishift start. Driver: xhyve

First setup (2 cores, download images): 6:05.91 Second start (2 cores): 2:25.00 Third start (2 cores): 2:43.49 Fourth start (8 cores): 2:24.92 Fifth start (8 cores): 2:08.23 Sixst start (8 cores): 2:05.49

Driver: drivekit

First setup (2 cores, download images): 5:51.98 Second start (8 cores): 2:12.71

Test machine:

MacBook Pro (Retina, 15-inch, Mid 2015) Processor 2.8 GHz Intel Core i7 Memory 16 GB 1600 MHz DDR3 Graphics Inter Iris Pro 1536 MB

After experimenting with xhyve switching back to drivekit produced almost the same results. Using this virutalization solution the startup time of an Open Shift cluster is around 2 minutes.

Using VMware

• Install Fedora
• Setup ssh in Fedora
• Install Docker CE
• Setup insecure registry
• Install oc
• run sudo cluster up with hostname