Most cloud providers try to attract customers with Infrastructure as a Service (IaaS), for which they receive access to configurable virtual machines (VMs) in the cloud. Because almost every application is able to operate in an IaaS environment, it offers the greatest flexibility across all services – accompanied, however, by high administrative effort. Platform as a Service (PaaS), on the other hand, appeals to developers who need a suitable environment to build and test an application but are not in the least interested in setting it up themselves.

IaaS, then, cannot be accomplished on the fly, and certainly not without in-depth knowledge of system administration. The customer is not merely free to configure it – they must. Because the basic images used in clouds are mostly minimal versions of the various distributions, the entire overhead of setting up the system rests on the admin. Developers, however, only need to know whether their programs function, and the admin just wants to be in position to manage the VM. The concept of PaaS brings admins and developers together as a helpful building block for DevOps. Red Hat presents OpenShift as a platform, providing PaaS as a finished product for businesses; however, does it deliver what the red-hatted ones promise?

The PaaS Alternative

A pre-made PaaS environment allows you to start new development environments at lightning speed with all the important tools (e.g., Git and Jenkins). Continuous integration is the goal: Virtual systems, in which the testing application is available and executable, immediately arise from the source code repositories used by developers to enter their modifications. This principle does require suitable tools and processes that work together.

The final step of the process is rolling out the application into productive operation. PaaS considerably reduces the effort required for the admin because, for a complete LAMP stack with an executable application, you essentially have to do nothing more than start the relevant container.

OpenShift's Variants

Red Hat offers interested parties several options for using OpenShift. Its most simple variants are "gears" (Red Hat-speak for containers) in the public OpenShift cloud operated by Red Hat itself. All functions mentioned so far in this article are integrated in this public cloud. If you only want to look at the container side of OpenShift, you are well served by this option: The barriers to entry are very low, and your first platform will be up and running within just a few minutes.

In the Free plan, up to three gears can operate free of charge; those needing more resources can switch to the Bronze or Silver plan. The Bronze plan is still basically free, but it does allow you to subscribe to further services for an additional charge. In the Silver plan, support is also part of the bargain (Figure 1).

Figure 1: OpenShift's Silver Plan also includes support.

Those unable to warm to a public cloud and who instead need the certainty that OpenShift will run on their own hardware, and only for their own purposes, might prefer the OpenShift Dedicated variant as an alternative to public installation. The Dedicated model is based on a platform hosted by Red Hat, but exclusively available to the respective customer. The provider takes care of both the hardware and the software; the responsibility of the user starts with operating the groups of containers (pods) that form the PaaS.

That sort of setup costs at least $48,000 a year, with the possible addition of further fees for more traffic or the provision of more application nodes [1]. However, compared with the costs of hardware alone for such a setup, that is a thoroughly reasonable price.

If, for whatever reason, you not only need exclusive hardware but also want to operate the platform yourself, you can turn to the OpenShift Enterprise version.

With the Enterprise version, you install OpenShift in your own data center, so you can retain full control, while Red Hat offers support from the sidelines. The Enterprise edition is not available without support. Red Hat maintains a refined silence on the OpenShift website [2] about the prices for the Enterprise license; as usual, the price to be paid could vary according to discounts granted. If you contact Red Hat sales, they send an evaluation license for the product on request.

Shift Toward Docker

The first version of the OpenShift environment appeared in 2011; in the meantime, it has reached version 3. Under the hood, it has changed substantially. The producer conducted various experiments, especially in the area of virtualization, before settling on Docker [3] and Kubernetes [4] in the current version.

The solution provided is sensible. Docker is effectively the standard when it comes to container virtualization, whereas Kubernetes is a management framework that facilitates the administration of Docker containers on a large number of servers. OpenShift is thus a complete solution: The host's operating system is part of the environment, along with all components that run on it, which allows you to operate application containers.

The user interfaces, such as APIs or GUIs, are also expressly included in the package. The admin can control the roll-out of containers so that the desired services run within OpenShift. Development is also relevant: OpenShift promises developers a complete and simple environment, in which container development and the use of applications already running are closely linked. The full path from idea to application in a production operation is thus covered.

In concrete terms, this means that during the first stage in an environment already prepared via OpenShift, the developer writes code that is then checked into a version control system (Git in OpenShift's case). With the click of a mouse, a complete virtual environment is automatically generated from a container image (cartridge) and the developer's code. All important components are included within this environment (Figure 2). If the application and the obligatory web server need other services (e.g., a database), they can also be started from OpenShift along with the application.

Figure 2: Applications at the push of a button: Selecting an application in OpenShift is all it takes to create a functioning solution.

As with all current Red Hat products, OpenShift is based on Enterprise Linux (RHEL) 7, at least for the classic approach. OpenShift also supports Red Hat's Atomic Platform as of version 3.1, which works with a system dependent on RHEL that is specially optimized for the operation of containers. In some respects, the Atomic variant differs markedly from a normal RHEL. For instance, it does not execute various system services as RPM packages, but as its own containers.

The classic RHEL is clearly the more sensible solution if infrastructure to operate RHEL (e.g., functioning automation) is available at the data center. Atomic, however, is better suited for new, greenfield installations that are unwilling to accept the overhead of a complete RHEL.