Kubernetes
Introduction
Kubernetes is an Open Source system that provides functionality to manage the lifecycle of containerised computing loads. It can achieve this over a clustered infrastructure, providing high availability, and scaling.
Definitions
Kubernetes: A container orchestration system.Container: Software packaging for a computing application, allowing it to be run in an isolated environment in a standard way.Isolated environment: Operating System features are used to separate an application from its environment and other computing workloads. Workload isolation provides security and resource governance.Orchestration: Automating software deployment, scaling, and management.
Technology Trajectory
Kubernetes was developed within Google, and was donated as a seed technology to the Cloud Native Computing Foundation (CNCF).
A range of interrelated systems and standards underpin and extend Kubernetes that promote compatibility, providing consistency and reliability.
The CNCF has a large eco-system of technologies that complement and rely on kubernetes.
Concepts
Promise theory
- The design of kubernetes relies on the Promise Theory analysis methodology.
- Promise Theory in kubernetes allows a resource to be modelled as voluntarily and autonomously co-operating with other resources in the kubernetes system
- The use of declarative specification follows in the form of the publishing of a Promise to the kubernetes system in the form of a resource definition
- Resource definitions are loaded via the kubernetes API
- The kubernetes API is used to interact with the kubernetes system, and the objects deployed in the system.
Clustering
Clustering provides a layer of abstraction for computing resources, spanning virtual or physical machines.
In a single machine instance the processes and applications interact with the machine's operating system apis.
In a cluster the processes and applications interact with the cluster system's apis.