Introduction to Kubernetes
The way software applications have been deployed, has evolved over a period of time. Better hardware resource utilisation has been one of the key objectives. Today, container based deployments are popular and one of the most preferred way of deployment.
Reference: what-is-kubernetes
What is a container?
A container is the runtime instantiation of a Container Image. It is a standard Linux process typically created through a clone() system call instead of fork() or exec().
There are two states of container
- rest
- running
When at rest, a container is a file( or set of files ) that is saved on disk. It is referred to as Container Image.
When you type the command to start a container, the Container Engine unpacks the required files and meta-data, then hands them off to the Linux kernel. In running state, containers are just a Linux process.
Container Terminology is a good primer to understand a little more in depth.
Open Container Initiative under The Linux Foundation is creating open industry standards around container formats and runtime.
Docker, Container Linux ( CoreOS Linux ), cri-o are few examples.
What is Kubernetes?
Containers provide mechanisms to bundle your applications and make them agnostics of the underlying hardware, however managing and orchestrating different containers comes with its own challenges. Borg is a cluster management system used within Google for managing and running containerized workload. This was open sourced in the year 2015 as Kubernetes, also known as K8s.
Kubernetes is a portable, extensible, open-source platform for managing containerized workloads and services, that facilitates both declarative configuration and automation.