Overview of Kubernetes & Docker In Simple Terms

I started to watch the Kubernetes for the Absolute Beginners — Hands-on course in Udemy. Here are the main take-aways from the “overview” part of the course in simple terms.

What is a container?

Containers provide a way to package and deliver applications so that they can be run very quickly with no set up time.

Different parts of an application are put in separate containers. The containers in an application are all run on top of one operating system.

Why is this good?

Using containers is better than running the whole application directly on your operating system because it avoids issues if different parts of your application use different libraries and have different dependencies. A container includes all of the libraries and dependencies required for the application code in that particular container.

Containers are a bit similar to Virtual Machines but Virtual Machines each have their own operating system. This makes them slower to start and means they have a much higher overhead. Containers are a lot “lighter weight”.

What is Docker?

Docker is an open source platform for building applications built on containers. Docker makes it easy for developers to build and launch a container.

What is Kubernetes?

Kubernetes is a container orchestrator technology. It allows you to manage all of your container resources in one place in an automated way. It would be really complex and would take a lot of time and effort to do all of that manually.

Kubernetes lets you control a cluster of “worker” nodes (i.e. virtual machines). It schedules containers (grouped into “pods”) to run on the worker nodes based on their resources — this is great for sharing the load. The “master” node is responsible for controlling the “worker” nodes.

Next Steps

I will continue to build on my understanding of containers and Kubernetes by following the rest of the course and by trying some of the tutorials in the Kubernetes documentation here.

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