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What is Application Containerization?

Application containerization is more than just a new buzz-word in cloud computing; it is changing the way in which resources are deployed into the cloud. However, many people are still coming to grips with the concept of application containerization, how it works, and the benefits it can deliver.

Most people understand the term “cloud computing” relates to the renting of computing services over the Internet from Cloud Service Providers (AWS, Azure, Google, etc.). Cloud computing breaks down into three broad categories – Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS) – often called the “cloud computing stack” because they build on top of one another.

The benefits of cloud computing are easily seen at the IaaS level; where, rather than building a physical, on-premises IT infrastructure, businesses can simply pay for the computing services they need as they want them, on demand. The advantages of cost, scalability, flexibility and low maintenance overheads have driven IaaS cloud computing to be a $50 billion industry in little more than a decade.

However, IaaS cloud computing also has its issues. In order to take advantage of the benefits, businesses have to rent virtual machines (VMs or “instances”) which replicate the features of a physical IT environment. This means paying for a server complete with its own operating system and the software required to run the operating system, even if you only want to launch a single application.

Where Application Containerization Comes Into the Picture

By comparison, application containerization allows businesses to launch individual applications without the need to rent an entire VM. It does this by “virtualizing” an operating system and giving containers access to a single operating system kernel – each container comprising the application and the software required for the application to run (settings, libraries, storage, etc.).

The process of application containerization allows multiple applications to be distributed across a single host operating system without requiring their own VM, which can lead to significant cost savings. Whereas previously, a server hosting eight applications in eight VMs would have eight copies of the operating system running in each VM, ten containers can share the same operating system.

In addition to significant cost savings, application containerization allows for greater portability. This can accelerate the process of testing applications across different operating systems because there is no waiting for the operating system to boot up. Furthermore, if the application crashes during testing, it only takes down the isolated container rather than the entire operating system.

One further benefit of application containerization is that containers can be clustered together for easy scalability or to work together as micro-services. In the latter case, if an application requires updating or replacing, it can be done in isolation of other applications and without the need to stop the entire service. The lower costs, greater portability and minimal downtime are three reasons why application containerization has become more than just a new buzzword in cloud computing and is changing the way in which resources are deployed into the cloud.

The Downsides of Application Containerization

Unfortunately, there are downsides to application containerization. Some of these – for example, container networking – are being resolved as more businesses take advantage of application containerization. However, container security and complexity are remaining issues, as is the potential for costs to spiral out of control as they often do when businesses adopt new technologies.

The security issue evolves from the process of containers sharing the same operating system. If a vulnerability in the operating system or the kernel is exploited, it will affect the security of all the applications connected to the operating system. Consequently, security policies have to be turned on for every application, with activities other than essential ones forbidden.

Containers also add more operational complexity than you might at first assume, adding more to orchestrate and requiring additional management.

With regard to costs, the risk exists that developers will launch multiple containers and fail to terminate them when they are no longer required. Due to the number of containers being launched compared to VMs, it will not take long for container-related cloud waste to match that of VM-related cloud waste – estimated to be $12.9 billion per year in this blog post.

The problem with controlling cloud spend using cloud management software is that many solutions fail to identify unused containers because the solutions are host-centric rather than role-centric.