# What Is Kubernetes?
URL:: https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/
Author:: kubernetes.io
## Highlights
> Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. ([View Highlight](https://instapaper.com/read/1372129687/15629335))
> The name Kubernetes originates from Greek, meaning helmsman or pilot. Google open-sourced the Kubernetes project in 2014. Kubernetes combines over 15 years of Google's experience running production workloads at scale with best-of-breed ideas and practices from the community. ([View Highlight](https://instapaper.com/read/1372129687/15629337))
> organizations ran applications on physical servers. There was no way to define resource boundaries for applications in a physical server, and this caused resource allocation issues. ([View Highlight](https://instapaper.com/read/1372129687/15629341))
> Virtualized deployment era ([View Highlight](https://instapaper.com/read/1372129687/15629344))
> Traditional deployment era: ([View Highlight](https://instapaper.com/read/1372129687/15629345))
> Virtualization allows better utilization of resources in a physical server and allows better scalability because an application can be added or updated easily, reduces hardware costs, and much more. With virtualization you can present a set of physical resources as a cluster of disposable virtual machines. ([View Highlight](https://instapaper.com/read/1372129687/15629347))
> Container deployment era: Containers are similar to VMs, but they have relaxed isolation properties to share the Operating System (OS) among the applications ([View Highlight](https://instapaper.com/read/1372129687/15629350))
> Similar to a VM, a container has its own filesystem, share of CPU, memory, process space, and more. As they are decoupled from the underlying infrastructure, they are portable across clouds and OS distributions. ([View Highlight](https://instapaper.com/read/1372129687/15629352))
> Containers have become popular because they provide extra benefits, such as:
> Agile application creation and deployment: increased ease and efficiency of container image creation compared to VM image use.
> Continuous development, integration, and deployment: provides for reliable and frequent container image build and deployment with quick and easy rollbacks (due to image immutability).
> Dev and Ops separation of concerns: create application container images at build/release time rather than deployment time, thereby decoupling applications from infrastructure.
> Observability not only surfaces OS-level information and metrics, but also application health and other signals.
> Environmental consistency across development, testing, and production: Runs the same on a laptop as it does in the cloud.
> Cloud and OS distribution portability: Runs on Ubuntu, RHEL, CoreOS, on-premises, on major public clouds, and anywhere else.
> Application-centric management: Raises the level of abstraction from running an OS on virtual hardware to running an application on an OS using logical resources.
> Loosely coupled, distributed, elastic, liberated micro-services: applications are broken into smaller, independent pieces and can be deployed and managed dynamically – not a monolithic stack running on one big single-purpose machine.
> Resource isolation: predictable application performance.
> Resource utilization: high efficiency and density. ([View Highlight](https://instapaper.com/read/1372129687/15629362))
> Kubernetes provides you with:
> Service discovery and load balancing Kubernetes can expose a container using the DNS name or using their own IP address. If traffic to a container is high, Kubernetes is able to load balance and distribute the network traffic so that the deployment is stable.
> Storage orchestration Kubernetes allows you to automatically mount a storage system of your choice, such as local storages, public cloud providers, and more.
> Automated rollouts and rollbacks You can describe the desired state for your deployed containers using Kubernetes, and it can change the actual state to the desired state at a controlled rate. For example, you can automate Kubernetes to create new containers for your deployment, remove existing containers and adopt all their resources to the new container.
> Automatic bin packing You provide Kubernetes with a cluster of nodes that it can use to run containerized tasks. You tell Kubernetes how much CPU and memory (RAM) each container needs. Kubernetes can fit containers onto your nodes to make the best use of your resources.
> Self-healing Kubernetes restarts containers that fail, replaces containers, kills containers that don't respond to your user-defined health check, and doesn't advertise them to clients until they are ready to serve.
> Secret and configuration management Kubernetes lets you store and manage sensitive information, such as passwords, OAuth tokens, and SSH keys. You can deploy and update secrets and application configuration without rebuilding your container images, and without exposing secrets in your stack configuration. ([View Highlight](https://instapaper.com/read/1372129687/15629369))
> Kubernetes is not a traditional, all-inclusive PaaS (Platform as a Service) system. Since Kubernetes operates at the container level rather than at the hardware level, it provides some generally applicable features common to PaaS offerings, such as deployment, scaling, load balancing, and lets users integrate their logging, monitoring, and alerting solutions. However, Kubernetes is not monolithic, and these default solutions are optional and pluggable. Kubernetes provides the building blocks for building developer platforms, but preserves user choice and flexibility where it is important. ([View Highlight](https://instapaper.com/read/1372129687/15629370))
> Does not deploy source code and does not build your application. Continuous Integration, Delivery, and Deployment (CI/CD) workflows are determined by organization cultures and preferences as well as technical requirements. ([View Highlight](https://instapaper.com/read/1372129687/15629371))
> Does not provide application-level services, such as middleware (for example, message buses), data-processing frameworks (for example, Spark), databases (for example, MySQL), caches, nor cluster storage systems (for example, Ceph) as built-in services. Such components can run on Kubernetes, and/or can be accessed by applications running on Kubernetes through portable mechanisms, such as the Open Service Broker.
> Does not dictate logging, monitoring, or alerting solutions. It provides some integrations as proof of concept, and mechanisms to collect and export metrics. ([View Highlight](https://instapaper.com/read/1372129687/15629373))
> Additionally, Kubernetes is not a mere orchestration system. In fact, it eliminates the need for orchestration. The technical definition of orchestration is execution of a defined workflow: first do A, then B, then C. In contrast, Kubernetes comprises a set of independent, composable control processes that continuously drive the current state towards the provided desired state. It shouldn't matter how you get from A to C. Centralized control is also not required. This results in a system that is easier to use and more powerful, robust, resilient, and extensible. ([View Highlight](https://instapaper.com/read/1372129687/15629376))
---
Title: What Is Kubernetes?
Author: kubernetes.io
Tags: readwise, articles
date: 2024-01-30
---
# What Is Kubernetes?
URL:: https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/
Author:: kubernetes.io
## AI-Generated Summary
None
## Highlights
> Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation. ([View Highlight](https://instapaper.com/read/1372129687/15629335))
> The name Kubernetes originates from Greek, meaning helmsman or pilot. Google open-sourced the Kubernetes project in 2014. Kubernetes combines over 15 years of Google's experience running production workloads at scale with best-of-breed ideas and practices from the community. ([View Highlight](https://instapaper.com/read/1372129687/15629337))
> organizations ran applications on physical servers. There was no way to define resource boundaries for applications in a physical server, and this caused resource allocation issues. ([View Highlight](https://instapaper.com/read/1372129687/15629341))
> Virtualized deployment era ([View Highlight](https://instapaper.com/read/1372129687/15629344))
> Traditional deployment era: ([View Highlight](https://instapaper.com/read/1372129687/15629345))
> Virtualization allows better utilization of resources in a physical server and allows better scalability because an application can be added or updated easily, reduces hardware costs, and much more. With virtualization you can present a set of physical resources as a cluster of disposable virtual machines. ([View Highlight](https://instapaper.com/read/1372129687/15629347))
> Container deployment era: Containers are similar to VMs, but they have relaxed isolation properties to share the Operating System (OS) among the applications ([View Highlight](https://instapaper.com/read/1372129687/15629350))
> Similar to a VM, a container has its own filesystem, share of CPU, memory, process space, and more. As they are decoupled from the underlying infrastructure, they are portable across clouds and OS distributions. ([View Highlight](https://instapaper.com/read/1372129687/15629352))
> Containers have become popular because they provide extra benefits, such as:
> Agile application creation and deployment: increased ease and efficiency of container image creation compared to VM image use.
> Continuous development, integration, and deployment: provides for reliable and frequent container image build and deployment with quick and easy rollbacks (due to image immutability).
> Dev and Ops separation of concerns: create application container images at build/release time rather than deployment time, thereby decoupling applications from infrastructure.
> Observability not only surfaces OS-level information and metrics, but also application health and other signals.
> Environmental consistency across development, testing, and production: Runs the same on a laptop as it does in the cloud.
> Cloud and OS distribution portability: Runs on Ubuntu, RHEL, CoreOS, on-premises, on major public clouds, and anywhere else.
> Application-centric management: Raises the level of abstraction from running an OS on virtual hardware to running an application on an OS using logical resources.
> Loosely coupled, distributed, elastic, liberated micro-services: applications are broken into smaller, independent pieces and can be deployed and managed dynamically – not a monolithic stack running on one big single-purpose machine.
> Resource isolation: predictable application performance.
> Resource utilization: high efficiency and density. ([View Highlight](https://instapaper.com/read/1372129687/15629362))
> Kubernetes provides you with:
> Service discovery and load balancing Kubernetes can expose a container using the DNS name or using their own IP address. If traffic to a container is high, Kubernetes is able to load balance and distribute the network traffic so that the deployment is stable.
> Storage orchestration Kubernetes allows you to automatically mount a storage system of your choice, such as local storages, public cloud providers, and more.
> Automated rollouts and rollbacks You can describe the desired state for your deployed containers using Kubernetes, and it can change the actual state to the desired state at a controlled rate. For example, you can automate Kubernetes to create new containers for your deployment, remove existing containers and adopt all their resources to the new container.
> Automatic bin packing You provide Kubernetes with a cluster of nodes that it can use to run containerized tasks. You tell Kubernetes how much CPU and memory (RAM) each container needs. Kubernetes can fit containers onto your nodes to make the best use of your resources.
> Self-healing Kubernetes restarts containers that fail, replaces containers, kills containers that don't respond to your user-defined health check, and doesn't advertise them to clients until they are ready to serve.
> Secret and configuration management Kubernetes lets you store and manage sensitive information, such as passwords, OAuth tokens, and SSH keys. You can deploy and update secrets and application configuration without rebuilding your container images, and without exposing secrets in your stack configuration. ([View Highlight](https://instapaper.com/read/1372129687/15629369))
> Kubernetes is not a traditional, all-inclusive PaaS (Platform as a Service) system. Since Kubernetes operates at the container level rather than at the hardware level, it provides some generally applicable features common to PaaS offerings, such as deployment, scaling, load balancing, and lets users integrate their logging, monitoring, and alerting solutions. However, Kubernetes is not monolithic, and these default solutions are optional and pluggable. Kubernetes provides the building blocks for building developer platforms, but preserves user choice and flexibility where it is important. ([View Highlight](https://instapaper.com/read/1372129687/15629370))
> Does not deploy source code and does not build your application. Continuous Integration, Delivery, and Deployment (CI/CD) workflows are determined by organization cultures and preferences as well as technical requirements. ([View Highlight](https://instapaper.com/read/1372129687/15629371))
> Does not provide application-level services, such as middleware (for example, message buses), data-processing frameworks (for example, Spark), databases (for example, MySQL), caches, nor cluster storage systems (for example, Ceph) as built-in services. Such components can run on Kubernetes, and/or can be accessed by applications running on Kubernetes through portable mechanisms, such as the Open Service Broker.
> Does not dictate logging, monitoring, or alerting solutions. It provides some integrations as proof of concept, and mechanisms to collect and export metrics. ([View Highlight](https://instapaper.com/read/1372129687/15629373))
> Additionally, Kubernetes is not a mere orchestration system. In fact, it eliminates the need for orchestration. The technical definition of orchestration is execution of a defined workflow: first do A, then B, then C. In contrast, Kubernetes comprises a set of independent, composable control processes that continuously drive the current state towards the provided desired state. It shouldn't matter how you get from A to C. Centralized control is also not required. This results in a system that is easier to use and more powerful, robust, resilient, and extensible. ([View Highlight](https://instapaper.com/read/1372129687/15629376))