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

Architecture


The architecture of a Docker Swarm from a 30,000-foot view consists of two main parts—a raft consensus group of an odd number of manager nodes, and a group of worker nodes that communicate with each other over a gossip network, also called the control plane. The following figure illustrates this architecture:

High-level architecture of a Docker Swarm

The manager nodes manage the swarm whilst the worker nodes execute the applications deployed into the swarm. Each manager has a complete copy of the full state of the swarm in its local raft store. Managers communicate with each other in a synchronous way and the raft stores are always in sync.

The workers, on the other hand, communicate with each other asynchronously for scalability reasons. There can be hundreds if not thousands of worker nodes in a swarm. Now that we have a high-level overview of what a Docker Swarm is, let's describe all the individual elements of a Docker Swarm in more detail.