When comparing OpenShift vs Kubernetes, the Slant community recommends Kubernetes for most people. In the question“What are the best Docker orchestration tools?” Kubernetes is ranked 1st while OpenShift is ranked 6th. The most important reason people chose Kubernetes is:
Kubernetes is free and open source.
Ranked in these QuestionsQuestion Ranking
Pro Built-in continuous integration
Continuous integration is not only built-in OpenShift, it's actually a standard part the workflow.
Pro Can be used to introduce specialized tasks through the application hosted on it
Because of its high flexibility and customization power, OpenShift can be used to create specialized tasks for the application being hosted on it. For example, an entire array of dynos (also known as gears) can be dedicated to media transcoding in order to build a custom media converter infrastructure.
Pro Small learning curve
Learning to use OpenShift is pretty easy. Most environments can be set up in a few simple steps and for everything else the official documentation and third-party resources are extremely helpful.
Pro Open Source
Kubernetes is free and open source.
Pro Built on several years of experience with containers
Kubernetes was built on top of several years of experience from Google working on containers in production. It's a little opinionated on how containers should work and behave, but if used correctly it can help you achieve fault-tolerant systems.
Pro Fault tolerant
Almost everything in Kubernetes is designed to handle if parts of it fail or if your service crashed for whatever reason. So it's particularly adapted if you've a cluster (even a very small one).
Pro Works well with modern operating systems
Kubernetes works very well with modern environments (such as CoreOS or Red Hat Atomc) which offer lightweight computing nodes that you don't have to manage, since they are managed for you.
Pro Supported on several PaaS
Kubernetes is currently supported by Google Compute Engine, Rackspace, Microsoft Azure, and vSphere. Work is being done to support Kubernetes on OpenShift and CloudFoundry.
Pro Easy to do grouping tasks
Kubernetes uses labels which are key-value pairs that are attached to objects, usually pods. They are used to specify the characteristics of an object like the version, tier, etc. Labels are used to identify objects or groups of objects according to different characteristics that they may have, for example they can be used to identify all the pods that are included in the backend tier.
Through labels it's easier to do grouping tasks for pods or containers, like moving pods to different groups or assigning them to load-balanced groups.
Pro Great starting point for beginners
Kubernetes great for beginners who are just starting to work on clustering. It's probably the quickest and easiest way to start experimenting and learning cluster oriented development.
Con Official customer support is lacking
OpenShift seems to rely more on written documentation and on the community to solve any problem users may have. The forums and IRC channel are active and very helpful, but the official customer support could be better.
Con Cannot define containers through the Docker CLI
Kubernetes was not written for docker clustering alone. It uses a different API, configuration and different YAML definitions. So you can't use the Docker CLI or Docker Compose to define your containers. Everything has to be done from scratch.
Con Windows restrictions
Windows compatibility rules, the host OS version must match the container base image OS version. Only Windows containers with Windows Server 2019 are supported. Also other restrictions are present.
Con If used on an existing system, some re-organizing may be needed
Because of how opinionated Kubernetes is, it may be necessary to change some things if you decide to use Kubernetes as an orchestration tool in an existing application.
Con Sometimes Pods refuse to (re)start automatically
It happens that a Pod needs a manual kick before it runs properly, especially if you're near full utilisation of your machine resources. Sometimes it is just a long delay.