Years ago, a typical deployment of an application required a physical server. This was not because of choice but out of necessity as there were simply no other options available. Now, this approach has several drawbacks.
For example, there was no easy way for developers to define what resources an application would use on the server. So, for instance, with multiple applications running on the same server, there could be instances where one application used all or most of the resources.
The inevitable result would be that the other applications would underperform. The obvious solution for this problem is to run each application on a different server. The problem here is that this approach doesn’t scale properly. Besides, there is a significant cost implication if each application must be run on a separate server.
Moving up from this, developers started using virtualization as a solution. In this way, they were able to use multiple virtual machines on a single server. As such, each application would run on its own virtual machine.
Although this is a solution to the resource management problem mentioned above, it’s still resource-intensive because each virtual machine is actually a full machine running on the server. As a result, it still uses significant resources and can’t scale up or down as the situation requires.
Enter the container era. Containers are similar to virtual machines, but they share the operating system among the various applications. As a result, containers are far more lightweight than a typical virtual machine. Yet, each has its file system, a share of CPU, and memory available. And, because containers are decoupled from the underlying infrastructure, they are more portable than virtual machines.
But here’s the problem. Although containers are an effective way to run applications, those containers need to be managed to make sure that there’s no downtime. This could get complicated especially if there are many containers.
And that’s where the Kubernetes comes in. It succeeds in effectively solving these problems. But what exactly is Kubernetes? In this post, we’ll look at this tool in more detail.
What is Kubernetes?
Kubernetes is a portable, extensible, open-source platform that allows developers to manage containerized workloads and services. As such, it facilitates both declarative configuration and automation. Also, because of its popularity, it has a large, and rapidly growing ecosystem of Kubernetes services, support, and tools.
It features the ability to automate app provisioning based on the level of traffic in production. And it doesn’t matter if these containers are in different data centers, on different hardware, or hosted at different hosting providers.
As the demand for an application increases, Kubernetes can scale up the according to the demand and degrades instances when the demand is no longer needed. In simple terms, it allows applications to scale up or down as the circumstances require.
In practice, this also means that, if a container goes down, Kubernetes starts another up automatically. This makes distributed systems easier to run and manage while also providing them with the resiliency needed to ensure that there’s no downtime.
In addition, it has advanced load-balancing capabilities that enable traffic routing to different containers, storage orchestration, can automate rollouts and rollbacks, can automate bin packing, and is self-healing.
What it Isn’t?
Despite its benefits, Kubernetes is not a traditional all-inclusive Platform as a Service (PaaS) platform. This is because it operates at the container level rather than the hardware level.
So, although it provides some features of common PaaS platforms, it’s not monolithic. As such, it provides the building blocks to build developer platforms, but it ensures user choice and flexibility where it is important.
As a result, Kubernetes:
- Does not limit the types of applications supported.
- Does not deploy source code and does not build any applications.
- Does not provide any application-level services.
- Does not dictate logging, monitoring, and alerting solutions to developers.
- Does not dictate a configuration language or system.
- Does not provide or adopt any pre-configured systems.
- Is not an ordinary orchestration system. Rather, it’s a set of independent, configurable, and composable control processes that drive the state of an application to a provided, desired state.
Kubernetes vs Docker
While Kubernetes is a container orchestration platform, Docker is a container virtualization standard. It’s the main container virtualization standard used with Kubernetes. So, in simple terms, Docker creates the containers while Kubernetes determines what the containers should do.
A perfect way to explain this is by using an example. For a moment, imagine a train on a track with a few cars. In this example, the cars are the containers, and they are taken on the track to each destination where they must offload their payload. Kubernetes is the track that determines where the cars should go and what they should do.
Keep in mind, though that apart from Kubernetes, several other orchestration platforms work with Docker.
Some of these alternatives to Kubernetes are:
- Docker Swarm. Docker Swarm is the native clustering engine for Docker.
- Nomad. Nomad is a simple and flexible workload orchestrator that’s used to deploy and manage both containerized and non-containerized applications.
- OpenStack. OpenStack is a cloud operating system that controls large pools of computing, networking, and storage infrastructure throughout a data center.
- Docker Compose. Compose is a native Docker tool that’s used for defining and running multi-container Docker applications.
- Rancher. Rancher is a complete software stack for teams adopting containers and developing containerized applications.
- DC/OS. DC/OS is a distributed operating system based on the Apache Mesos distributed systems kernel. It allows developers to manage multiple machines in the cloud or on-site.
- Apache Mesos. Apache Mesos is an open-source project to manage computer clusters which abstract CPU, memory, storage, and other compute resources away from machines and enable fault-tolerant and distributed system to be easily built and effectively run.
Containerization has revolutionized the software development industry. It allows developers to speed up deployment and building applications without the limitations of traditional on-premise infrastructure or virtualization.
They’re not perfect, though, and to minimize downtime, containers should be managed, which could become a challenge. Fortunately, Kubernetes offers the perfect solution. It allows for the orchestration of containerized applications that enable efficient scaling, both up and down, as the circumstances dictate and virtually eliminate downtime.