1. What is
Kubernetes, or k8s (k, 8 characters, s...get it?), or
kube if you're into brevity,
is an open source platform that automates Linux container operations. It eliminates many of the
manual processes involved in deploying and scaling containerized applications. In other words, you
can cluster together groups of hosts running Linux containers, and Kubernetes helps you easily and
efficiently manage those clusters. Kubernetes clusters can span hosts across public, private, or
hybrid clouds. For this reason, Kubernetes is an ideal platform for hosting cloud‐native
applications that require rapid scaling, like real‐time data streaming through Apache Kafka.
Kubernetes was originally developed and designed by engineers at Google. Google was one of the early contributors to Linux container technology and has talked publicly about how everything at Google runs in containers. (This is the technology behind Google's cloud services). Google generates more than 2 billion container deployments a week, all powered by an internal platform: Borg. Borg was the predecessor to Kubernetes and the lessons learned from developing Borg over the years became the primary influence behind much of Kubernetes technology.
Red Hat was one of the first companies to work with Google on Kubernetes, even prior to launch, and has become the 2nd leading contributor to the Kubernetes upstream project. Google donated the Kubernetes project to the newly formed Cloud Native Computing Foundation in 2015.
What can you do with Kubernetes?
The primary advantage of using Kubernetes in your environment, especially if you are optimizing app dev for the cloud, is that it gives you the platform to schedule and run containers on clusters of physical or virtual machines (VMs). More broadly, it helps you fully implement and rely on a container‐based infrastructure in production environments. And because Kubernetes is all about automation of operational tasks, you can do many of the same things that other application platforms or management systems let you do, but for your containers.
With Kubernetes you can:
However, Kubernetes relies on other projects to fully provide these orchestrated services. With the addition of other open source projects, you can fully realize the power of Kubernetes. These necessary pieces include (among others):
Learn to speak Kubernetes
Like any technology, there are a lot of words specific to the technology that can be a barrier to entry. Let's break down some of the more common terms to help you understand Kubernetes.
Master: The machine that controls Kubernetes nodes. This is where all task assignments originate.
Node: These machines perform the requested, assigned tasks. The Kubernetes master controls them.
Pod: A group of one or more containers deployed to a single node. All containers in a pod share an IP address, IPC, hostname, and other resources. Pods abstract network and storage away from the underlying container. This lets you move containers around the cluster more easily.
Replication controller: This controls how many identical copies of a pod should be running somewhere on the cluster.
Service: This decouples work definitions from the pods. Kubernetes service proxies automatically get service requests to the right pod‐no matter where it moves to in the cluster or even if it’s been replaced.
Kubelet:This service runs on nodes, reads the container manifests, and ensures the defined containers are started and running.
kubectl:This is the command line configuration tool for Kubernetes.
Using Kubernetes in production
Kubernetes is open source and as such, there's not a formalized support structure around that technology‐at least not one you'd trust your business on. If you had an issue with your implementation of Kubernetes, while running in production, you're not going to be very happy. And your customers probably won't, either.
That's where Red Hat OpenShift Container Platform comes in. OpenShift Container Platform is Kubernetes for the enterprise‐and a lot more. It includes all of the extra pieces of technology that makes Kubernetes powerful and viable for the enterprise, including: registry, networking, telemetry, security, automation, and services. With OpenShift Container Platform, your developers can make new containerized apps, host them, and deploy them in the cloud with the scalability, control, and orchestration that can turn a good idea into new business quickly and easily.
Best of all, OpenShift Container Platform is supported and developed by the #1 leader in open source, Red Hat.
Why do you need Kubernetes?
Real production apps span multiple containers. Those containers must be deployed across multiple server hosts. Security for containers is multilayered and can be complicated. That's where Kubernetes can help. Kubernetes gives you the orchestration and management capabilities required to deploy containers, at scale, for these workloads. Kubernetes orchestration allows you to build application services that span multiple containers, schedule those containers across a cluster, scale those containers, and manage the health of those containers over time. With Kubernetes you can take real steps towards better IT security.
Kubernetes also needs to integrate with networking, storage, security, telemetry, and other services to provide a comprehensive container infrastructure.
Of course, this depends on how you're using containers in your environment. A rudimentary application of Linux containers treats them as fast, efficient virtual machines. Once you scale this to a production environment and multiple applications, it's clear that you need multiple, colocated containers working together to deliver the individual services. This significantly multiplies the number of containers in your environment and as those containers accumulate, the complexity also grows.
Kubernetes fixes a lot of common problems with container proliferation by sorting containers
pods.Pods add a layer of abstraction to grouped containers, which helps you
schedule workloads and provide necessary services‐like networking and storage‐to those
containers. Other parts of Kubernetes help you load balance across these pods and ensure you have
the right number of containers running to support your workloads.
With the right implementation of Kubernetes‐and with the help of other open source projects like Atomic Registry, Open vSwitch, heapster, OAuth, and SELinux‐you can orchestrate all parts of your container infrastructure.