Openshift overview in brief

Openshift Website

Openshift web site.

Openshift Admin Guide

If you are a system adminstrator and you want to learn more about providing OpenShift as a development platform, have a look at the Administration Guide.

Difference Between IaaS, PaaS, and SaaS


  • Infrastructure as a Service (IaaS) is when a provider spins up computers for you on demand with certain predefined virtual hardware configurations.
  • you are still responsible for installing and maintaining the operating system and server packages, configuring the network, and doing all the basic system administration


  • With SaaS you just sign up for the service and start using it.
  • You may be able to make some customizations, but you’re limited to what the service provider allows you to do.


  • Platform as a Service (PaaS) is primarily targeted at application developers and programmers.
  • With PaaS, you issue a few commands (which could be in a web console) and the platform spins up the development environment along with all the “server” pieces you need to run your application.

The Three Versions of OpenShift

OpenShift is Red Hat’s PaaS. There are 3 versions:

OpenShift Origin

  • free
  • open source
  • on GitHub
  • released under Apache 2 License
  • Approximately once every three weeks (the length of a sprint), Origin is packaged up and released as a new version of OpenShift Online

OpenShift Online

  • Red Hat takes care of hosting the PaaS on Amazon Web Services (AWS)
  • you just create an account for it.
  • All the server work, such as updating the OS and managing networks, is covered by the OpenShift operations team.
  • You are free to focus on your application and its code.

OpenShift Enterprise

  • currently released about once a quarter.
  • allows you to take the PaaS and run it anywhere you want, from bare metal in your data center to Rackspace or AWS.
  • It is a complete package with Red Hat Enterprise Linux and all the OpenShift bits on top of it.
  • It is fully supported by Red Hat and is intended for customers who want stability and a production-ready install out of the box.
  • Developers get all the speed and agility they want, without the usual wait for “machine” provisioning.

Glossary of Openshift Terms


  • a typical web application that will run on OpenShift.


  • a server container with a set of resources that allows users to run their applications.
  • small
    • 1 GB of disk space
    • 512 MB of RAM
  • medium
    • 1 GB of disk space
    • 1 GB of RAM
  • large
    • 1 GB of disk space
    • 2 GB of RAM


  • plugins that house the framework or components that can be used to create and run an application
  • One or more cartridges run on each gear
  • the same cartridge can run on many gears for clustering or scaling
  • Standalone
    • application servers that are set up to serve your web content, such as JBoss, Tomcat, Python, or Node.js.
    • one of these cartridges is sufficient to run an application.
  • Embedded
    • provides functionality to enhance your application, such as a database or Cron
    • cannot be used on its own to create an application.

Scalable application

  • Application scaling enables your application to react to changes in traffic and automatically allocate the necessary resources to handle your increased demand.
  • OpenShift monitors incoming web traffic and automatically brings up new gears with the appropriate web cartridge online to handle more requests
  • When traffic decreases, the platform retires the extra resources

Client tools, Web Console, or Eclipse plug-ins

  • can interact with the OpenShift platform via
    • RHC client command-line tools you install on your local machine,
    • the OpenShift Web Console, or
    • a plug-in you install in Eclipse to interact with your application in the OpenShift cloud.
  • The only time you must use these tools is when you are managing the infrastructure or components of your application.
  • For example, you would use these tools when creating an application or embedding a new cartridge
  • The rest of your work with your application will happen through Git and SSH

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