Kubernetes

What is Kubernetes?

Kubernetes, also known as K8s, is an open-source system for automating deployment, scaling, and management of containerized applications. It groups containers that make up an application into logical units for easy management and discovery. Kubernetes builds upon 15 years of experience of running production workloads at Google, combined with best-of-breed ideas and practices from the community.

With the widespread adoption of containers among organizations, Kubernetes, the container-centric management software, has become the de facto standard to deploy and operate containerized applications. Google Cloud is the birthplace of Kubernetes—originally developed at Google and released as open source in 2014.Providing automated container orchestration, Kubernetes improves your reliability and reduces the time and resources attributed to daily operations.

"Kubernetes (sometimes shortened to K8s with the 8 standing for the number of letters between the “K” and the “s”) is an open source system to deploy, scale, and manage containerized applications anywhere."

Kubernetes automates operational tasks of container management and includes built-in commands for deploying applications, rolling out changes to your applications, scaling your applications up and down to fit changing needs, monitoring your applications, and more—making it easier to manage applications.

Benefits of Kubernetes?

Automated operations :Kubernetes has built-in commands to handle a lot of the heavy lifting that goes into application management, allowing you to automate day-to-day operations. You can make sure applications are always running the way you intended them to run.

Infrastructure abstraction: When you install Kubernetes, it handles the compute, networking, and storage on behalf of your workloads. This allows developers to focus on applications and not worry about the underlying environment.

Service health monitoring: Kubernetes continuously runs health checks against your services, restarting containers that fail, or have stalled, and only making available services to users when it has confirmed they are running.

Kubernetes Features :

Automated rollouts and rollbacks :Kubernetes progressively rolls out changes to your application or its configuration, while monitoring application health to ensure it doesn't kill all your instances at the same time. If something goes wrong, Kubernetes will rollback the change for you.

Service Topology :Routing of service traffic based upon cluster topology.

Service discovery and load balancing:No need to modify your application to use an unfamiliar service discovery mechanism. Kubernetes gives Pods their own IP addresses and a single DNS name for a set of Pods, and can load-balance across them.

Storage orchestration :Automatically mount the storage system of your choice, whether from local storage, a public cloud provider such as GCP or AWS, or a network storage system such as NFS, iSCSI, Gluster, Ceph, Cinder, or Flocker.

Secret and configuration management :Deploy and update secrets and application configuration without rebuilding your image and without exposing secrets in your stack configuration.

Automatic bin packing:Automatically places containers based on their resource requirements and other constraints, while not sacrificing availability. Mix critical and best-effort workloads in order to drive up utilization and save even more resources.

Batch execution: In addition to services, Kubernetes can manage your batch and CI workloads, replacing containers that fail, if desired.

Kubernetes Case Study : Booking.com

Challenge

In 2016, Booking.com migrated to an OpenShift platform, which gave product developers faster access to infrastructure. But because Kubernetes was abstracted away from the developers, the infrastructure team became a "knowledge bottleneck" when challenges arose. Trying to scale that support wasn't sustainable.

"As our users learn Kubernetes and become more sophisticated Kubernetes users, they put pressure on us to provide a better, more native Kubernetes experience, which is great. It's a super healthy dynamic."

— BEN TYLER, PRINCIPAL DEVELOPER, B PLATFORM TRACK AT BOOKING.COM

Impressed by what the technology offered, but in need of enterprise features at its scale—the site handles more than 1.5 million room-night reservations a day on average—the team decided to adopt an OpenShift platform. This platform, which was wrapped in a Heroku-style, high-level CLI interface, "was definitely popular with our product developers," says Ben Tyler, Principal Developer, B Platform Track. "We gave them faster access to infrastructure."

And after a year of operating this platform, the infrastructure team found that it had become "a knowledge bottleneck," he says. "Most of the developers who used it did not know it was Kubernetes underneath. An application failure and a platform failure both looked like failures of that Heroku-style tool." Scaling the necessary support did not seem feasible or sustainable, so the platform team needed a new solution. The understanding of Kubernetes that they had gained operating the OpenShift platform gave them confidence to build a vanilla Kubernetes platform of their own and customize it to suit the company's needs.

"For entering the landscape, OpenShift was definitely very helpful. It shows you what the technology can do, and it makes it easy for you to use it. After we spent some time on it, we realized that we needed to learn Kubernetes better in order to fully use the potential of it. At that point, we made the shift to build our own Kubernetes platform. We definitely benefit in the long term for taking that step and investing the time in gaining that knowledge."

— EDUARD IACOBOAIA, SENIOR SYSTEM ADMINISTRATOR, B PLATFORM TRACK AT BOOKING.COM

"For entering the landscape, OpenShift was definitely very helpful," says Eduard Iacoboaia, Senior System Administrator, B Platform Track. "It shows you what the technology can do, and it makes it easy for you to use it. After we spent some time on it, we realized that we needed to learn Kubernetes better in order to fully use the potential of it. At that point, we made the shift to build our own Kubernetes platform. We definitely benefit in the long term for taking that step and investing the time in gaining that knowledge."

Iacoboaia's team had customized a lot of OpenShift tools to make them work at Booking.com, and "those integrations points were kind of fragile," he says. "We spent much more time understanding all the components of Kubernetes, how they work, how they interact with each other." That research led the team to switch from OpenShift's built-in Ansible playbooks to Puppet deployments, which are used for the rest of Booking's infrastructure. The control plane was also moved from inside the cluster onto bare metal, as the company runs tens of thousands of bare-metal servers and a large infrastructure for running applications on bare metal. (Booking runs Kubernetes in multiple clusters in multiple data centers across the various regions where it has compute.) "We decided to keep it as simple as possible and to also use the tools that we know best," says Iacoboaia.

There's other quantifiable evidence too: Before containers, creating a new service could take a couple of days if the developers understood Puppet, or weeks if they didn't. On the new platform, it takes 10 minutes. "We have a tutorial. You follow the tutorial. Your code is running. Then, it's business-logic time," says Tyler. "The time to gain access to resources is decreased enormously." About 500 new services were built in the first 8 months on the platform, with hundreds of releases per day.

The platform offers different "layers of contracts, so to speak," says Tyler. "At the very base, it's just Kubernetes. If you're a pro Kubernetes user, here's a Kubernetes API, just like you get from GKE or AKS. We're trying to be a provider on that same level. But our whole job inside the company is to be a bigger value add than just vanilla infrastructure, so we provide a set of base images for our main stacks, Perl and Java."

And "as our users learn Kubernetes and become more sophisticated Kubernetes users, they put pressure on us to provide a better more native Kubernetes experience, which is great," says Tyler. "It's a super healthy dynamic."The platform also includes other CNCF technologies, such as Envoy, Helm, and Prometheus. Most of the critical service traffic for Booking.com is routed through Envoy, and Prometheus is used primarily to monitor infrastructure components. Helm is consumed as a packaging standard. The team also developed and open sourced Shipper, an extension for Kubernetes to add more complex rollout strategies and multi-cluster orchestration.

To be sure, there have been internal discussions about the wisdom of building a Kubernetes platform from the ground up. "This is not really our core competency—Kubernetes and travel, they're kind of far apart, right?" says Tyler. "But we've made a couple of bets on CNCF components that have worked out really well for us. Envoy and Kubernetes, in particular, have been really beneficial to our organization. We were able to customize them, either because we could look at the source code or because they had extension points, and we were able to get value out of them very quickly without having to change any paradigms internally."

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