What are Kubernetes Containers? All you need to know about.

Kubernetes is an open-source, extensible, portable container management platform. Kubernetes has a sizable ecosystem that is designed for facilitating both automation and declarative configuration and managing containerized workloads and services.

What Is a Kubernetes Container?

What is a container in Kubernetes? Kubernetes containers resemble virtual machines (VMs), each with its own CPU share, filesystem, process space, memory, and more.

However, Kubernetes containers are considered lightweight because:

·         they can share the Operating System (OS) among applications due to their relaxed isolation properties

·         they are decoupled from the underlying infrastructure

·         they are portable across OS distributions and clouds

Each running Kubernetes container is repeatable. Users can expect the same behavior from a Kubernetes container regardless of its environment because included dependencies standardize performance.

Decoupling applications from underlying host infrastructure makes it simpler to deploy in various OS or cloud environments.

How Containers Work

Containers effectively virtualize the host operating system (or kernel) and isolate an application’s dependencies from other containers running on the same machine. Before containers, if you had multiple applications deployed on the same virtual machine (VM), any changes to shared dependencies could cause strange things to happen—so the tendency was to have one application per virtual machine.

The solution of one application per VM solved the isolation problem for conflicting dependencies, but it wasted a lot of resources (CPU and memory). This is because a VM runs not only your application but also a full operating system that needs resources too, so less would be available for your application to use.

Containers solve this problem with two pieces: a container engine and a container image, which is a package of an application and its dependencies. The container engine runs applications in containers isolating it from other applications running on the host machine. This removes the need to run a separate operating system for each application, allowing for higher resource utilization and lower costs.

Before containers, users typically deployed one application per virtual machine (VM), because deploying multiple applications could trigger strange results when shared dependencies were changed on one VM. Essentially, Kubernetes containers virtualize the host operating system and isolate the dependencies of an application from other running containers in the same environment. Running a single application for each VM resolves this issue, but wastes CPU and memory resources that should be available to the application. Kubernetes containers instead use a container engine to run applications that can all use the same operating system in containers isolated from other applications on the host VM. Kubernetes containers also use a container image, a ready-to-run software package of an application and its dependencies that contains everything needed to run an application: code, required runtime, system and application libraries, and essential setting default values. This reduces costs and allows for higher resource utilization.

Kubernetes containers support an extremely diverse variety of workloads, including stateful and stateless applications and data-processing workloads. Kubernetes containers can run any container applications. Furthermore, Kubernetes eliminates the need for orchestration or centralized control. Kubernetes includes multiple, independent control processes that drive the system towards the desired state continuously regardless of the specific order of steps. This produces a more dynamic, extensible, powerful, resilient, and robust system that is more user-friendly.

Why Use Kubernetes? Key Benefits

As the first Cloud Native Cloud Foundation (CNCF) project, Kubernetes is the fastest-growing project in the history of Open Source software. K8s became popular for the following key reasons:

Portability

Kubernetes offers portability, and faster, simpler deployment times. This means that companies can take advantage of multiple cloud providers if needed and can grow rapidly without having to re-architect their infrastructure.

Scalability

With Kubernetes' ability to run containers on one or more public cloud environments, in virtual machines, or on bare metal means that it can be deployed almost anywhere. And because Kubernetes has fundamentally changed the way development and deployments are made, teams can also scale much faster than they could in the past.

High Availability

Kubernetes addresses high availability at both the application and the infrastructure level. Adding a reliable storage layer to Kubernetes ensures that stateful workloads are highly available. In addition to this, the master components of a cluster can be configured for multi-node replication (multi-master) and this also ensures a higher availability.

Open Source

Since Kubernetes is open source, you can take advantage of the vast ecosystem of other open source tools designed specifically to work with Kubernetes without the lock-in of a closed/proprietary system.

Proven, and Battle Tested

A huge ecosystem of developers and tools with 5,608 GitHub repositories and counting means that you won’t be forging ahead into new territory without help.

Market Leader

Kubernetes was developed by and used and maintained by Google which not only gives it instant credibility, but can be trusted to fix bugs and release new features on a regular basis.

Kubernetes Architecture: Master and Worker Nodes

Kubernetes uses a master/slave communication model where there is at least one master and usually several worker nodes. The master (sometimes called the control plane) has three components and a data store:

·         API server—exposes the Kubernetes API for controlling the cluster

·         Controller manager—responsible for watching the cluster’s objects and resources and ensuring the desired state is consistent

·         Scheduler—responsible for scheduling compute requests on the cluster

·         etcd—an open-source distributed key value store used to hold the cluster data

The worker nodes provide the container runtime for your applications and have a few components responsible for communicating with the master and networking on every worker node:

·         Kubelet—responsible for communicating to the master and ensuring the containers are running on the node

·         Kube-proxy—enables the cluster to forward traffic to executing containers

·         Docker (container runtime)—provides the runtime environment for containers

Conclusion

Containers are the foundation of modern applications. Docker provides the toolset to easily create container images of your applications, and Kubernetes gives you the platform to run it all. Since the introduction of Kubernetes, you can safely say that almost all of the other orchestrators are either irrelevant or have taken a back seat to Kubernetes. And now just over four years later, every major public cloud provider has a managed Kubernetes service or is in the process of developing one.