Kubernetes and Openshift

VMs and Containers

VMs were designed by running software on top of physical servers to emulate a particular hardware system. A hypervisor, or a virtual machine monitor, is software, firmware, or hardware that creates and runs VMs. It’s what sits between the hardware and the virtual machine and is necessary to virtualize the server.

Each VM includes a separate operating system image, which adds overhead in memory and storage footprint. As it turns out, this issue adds complexity to all stages of a software development lifecycle — from development and test to production and disaster recovery. This approach also severely limits the portability of applications between public clouds, private clouds, and traditional data centers.

On the other hand, Containers sit on top of a physical server and its host OS — for example, Linux or Windows. Each container shares the host OS kernel and, usually, the binaries and libraries, too. Shared components are read-only. Containers are thus exceptionally “light” — they are only megabytes in size and take just seconds to start, versus gigabytes and minutes for a VM.

Containers also reduce management overhead. Because they share a common operating system, only a single operating system needs care and feeding for bug fixes, patches, and so on. This concept is similar to what we experience with hypervisor hosts: fewer management points but slightly higher fault domain. In short, containers are lighter weight and more portable than VMs.

About Kubernetes

Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. It has a large, rapidly growing ecosystem. Kubernetes services, support, and tools are widely available.

• Automates various manual processes: for instance, Kubernetes will control for you which server will host the container, how it will be launched etc.
• Interacts with several groups of containers: Kubernetes is able to manage more cluster at the same time
• Provides additional services: as well as the management of containers, Kubernetes offers security, networking and storage services
• Self-monitoring: Kubernetes checks constantly the health of nodes and containers
• Horizontal scaling: Kubernetes allows you scaling resources not only vertically but also horizontally, easily and quickly
• Storage orchestration: Kubernetes mounts and add storage system of your choice to run apps
• Automates rollouts and rollbacks: if after a change to your application something goes wrong, Kubernetes will rollback for you
• Container balancing: Kubernetes always knows where to place containers, by calculating the “best location” for them

Podman: Podman is an open source, OCI compliant container engine. It is driven by Red Hat and incorporates a few major differences from Docker, such as its daemonless architecture and support for rootless containers. At their core, both tools do the same thing: manage images and containers. One of Podman’s objectives is to have a Docker-compatible API. Hence almost all CLI commands from the Docker CLI are also available in Podman. It not only gives the flexibility of Docker Compose while developing applications, but it also makes the move to Kubernetes easier when applications are ready for the big leagues.

Limitations of Kubernetes

While Kubernetes offers portability, scalability, and automated, policy-driven management to its users, it is an incomplete solution. It does not include all of the components needed to build, run, and scale containers in production, such as the operating system, continuous integration/continuous delivery (CI/CD) tooling, application services, or storage. A large amount of work also needs to be done to set roles, access control, multitenancy, and secure default settings. Kubernetes does provide pluggable interfaces for many of these components and services, offering flexibility and choice for users.

Solution:

Openshift

OpenShift brings added-value features to complement Kubernetes, and that’s what makes it a turnkey platform, readily usable in production, and significantly improving the developer experience, as will be shown throughout the post. That’s what makes it both the successful Enterprise Platform-as-a-Service (PaaS) everyone knows about from a developer perspective, but also the very reliable Container-as-a-Service from a production standpoint.

With OpenShift, Red Hat has decided to shield this complexity and deliver a comprehensive platform, including not only Kubernetes at its core, but also all the essential open source tools that make it an enterprise-ready solution to confidently run your production. Of course, in case you already have your own stacks, then you can opt-out and plug into your existing solutions.

I would like to thank @Amel Mathai and @Daleep Bais for the session of industrial use cases of Kubernetes and Openshift. And also @Vimal Daga and @Preeti Chandak ma’am for organizing such an inspiring and erudite Session.