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

Swarm nodes


A swarm is a collection of nodes. We can classify a node as a physical computer or virtual machine (VM). Physical computers these days are often referred to as bare metal. People say we're running on bare metal to distinguish from running on a VM.

When we install Docker on such a node, we call this node a Docker host. The following figure illustrates a bit better what a node and what a Docker host is:

Bare metal and VM type Docker Swarm nodes

To become a member of a Docker Swarm, a node must also be a Docker host. A node in a Docker Swarm can have one of two roles. It can be a manager or it can be a worker. Manager nodes do what their name implies; they manage the swarm. The worker nodes in turn execute application workload.

Technically, a manager node can also be a worker node and thus run application workload, although that is not recommended, especially if the swarm is a production system running mission critical applications.

Swarm managers

Each Docker Swarm needs to have at least...