Book Image

Learn Docker - Fundamentals of Docker 18.x

By : Dr. Gabriel N. Schenker
Book Image

Learn Docker - Fundamentals of Docker 18.x

By: Dr. Gabriel N. Schenker

Overview of this book

Docker containers have revolutionized the software supply chain in small and big enterprises. Never before has a new technology so rapidly penetrated the top 500 enterprises worldwide. Companies that embrace containers and containerize their traditional mission-critical applications have reported savings of at least 50% in total maintenance cost and a reduction of 90% (or more) of the time required to deploy new versions of those applications. Furthermore they are benefitting from increased security just by using containers as opposed to running applications outside containers. This book starts from scratch, introducing you to Docker fundamentals and setting up an environment to work with it. Then we delve into concepts such as Docker containers, Docker images, Docker Compose, and so on. We will also cover the concepts of deployment, orchestration, networking, and security. Furthermore, we explain Docker functionalities on public clouds such as AWS. By the end of this book, you will have hands-on experience working with Docker containers and orchestrators such as SwarmKit and Kubernetes.
Table of Contents (21 chapters)
Title Page
Packt Upsell
Contributors
Preface
Index

Cluster nodes


Cluster nodes are the nodes onto which Kubernetes schedules application workload. They are the workhorses of the cluster. A Kubernetes cluster can have a few, dozens, hundreds, or even thousands of cluster nodes. Kubernetes has been built from the ground up for high scalability. Don't forget that Kubernetes has been modeled after Google Borg, which has been running tens of thousands of containers for years:

Kubernetes worker node

A worker node can run on a VM or on bare metal, on-premise, or in the cloud. Originally, worker nodes could only be configured on Linux. But since version 1.10 of Kubernetes, worker nodes can also run on Windows Server 2010. It is perfectly fine to have a mixed cluster with Linux and Windows worker nodes.

On each node, we have three services that need to run, which are described as follows:

  • Kubelet: This is the first and foremost service. Kubelet is what's called the primary node agent. The kubelet service uses pod specifications to make sure all of the...