Kubernetes for Absolute Beginners — Part 1
The above symbol denotes a person steering a ship. It also called as K8s — Kubernetes
Audience — Kubernetes Beginners
Kubernetes was first started by Google and was open-sourced and handed-over to CNCF (Cloud Native Computing Foundation)
Before we jump into Kubernetes , lets understand few important terms .
Microservices are Group of independent specialised services forming together a meaningful Application. Read more here on microservices
What is Kubernetes ? Kubernetes is a container orchestration tool.
What is a container ? A container is a standard unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another. These applications are called as microservices. Read more here on containers
What is container Orchestrator? An entity that manages the whole lifecycle of the container like but not exhaustive,
- Deployment
- Scaling
- Route
- Respond to changes
Let us take an example and explore the above.
Consider AWS is going to run a big developer conference in India. As part of the conference they have given contract to ABC caterers for serving food. ABC caterers create two groups in preparation to the event — Master Group and Workers Group.
Master group’s consist of various people; some of them to supervise infra, some to supervise logistics, some to setup payment desks, setup cooking area, monitor the availability of food, monitor the queues and direct them to correct food lanes (Like South Indian, Bengali, Gujarati, Chinese, Italian etc), they also bring in additional chefs as required. Each of them in Master’s group have their responsibility.
Worker group’s responsibility is to cater to customers on ground; Be it verifying the identity badges, payment processing, serving, preparing the food etc.
In this model, Master group can monitor and can respond to events (like more people coming in / less people); the billing counters can be scaled up /down; Chefs can be scaled up/down; People serving can scaled up/down; They can also respond to any other issues like someone injured and bring in a replacement.
The whole sequence of managing, monitoring, responding to events together forms orchestration
Take this to the tech world, with each of them running as a service. Consider you are running an e-commerce application. You will have authentication service, order service, notification service, payment service — each running as a separate microservice in containers and caters to incoming customer requests.
Similar to the catering analogy — you would need a Master group to manage these services and respond to events like route the incoming requests, maintain state of what is happening etc.
For ex: if ordering service goes down — Master group should bring up an exact replica of ordering service to ensure un-interrupted flow
Coming to Kubernetes, similar to the catering example — where the whole plan is setup and run from a big chamber/hall, its called as a cluster in Kubernetes world. The Master Group are called as Master Nodes and Worker groups are called as Worker Nodes and the whole setup is run in a cluster
Master nodes look after the entire cluster operations whereas the worker nodes run the business applications
In short, Kubernetes orchestrates the containers running in worker nodes end-to-end.
Reference: Nigel Poulton’s K8 course.
I would like to improve continuously, Please let me know if you have any feedbacks
Thanks to Ram for kindly reviewing this
Part II of the series I will explain the components of Master node and Worker nodes.
