Book Image

Learn Docker - Fundamentals of Docker 19.x - Second Edition

By : Dr. Gabriel N. Schenker
Book Image

Learn Docker - Fundamentals of Docker 19.x - Second Edition

By: Dr. Gabriel N. Schenker

Overview of this book

Containers enable you to package an application with all the components it needs, such as libraries and other dependencies, and ship it as one package. Docker containers have revolutionized the software supply chain in both small and large enterprises. Starting with an introduction to Docker fundamentals and setting up an environment to work with it, you’ll delve into concepts such as Docker containers, Docker images, and Docker Compose. As you progress, the book will help you explore deployment, orchestration, networking, and security. Finally, you’ll get to grips with Docker functionalities on public clouds such as Amazon Web Services (AWS), Azure, and Google Cloud Platform (GCP), and learn about Docker Enterprise Edition features. Additionally, you’ll also discover the benefits of increased security with the use of containers. By the end of this Docker book, you’ll be able to build, ship, and run a containerized, highly distributed application on Docker Swarm or Kubernetes, running on-premises or in the cloud.
Table of Contents (25 chapters)
1
Section 1: Motivation and Getting Started
4
Section 2: Containerization, from Beginner to Black Belt
11
Section 3: Orchestration Fundamentals and Docker Swarm
18
Section 4: Docker, Kubernetes, and the Cloud

Defining liveness and readiness

Container orchestration systems such as Kubernetes and Docker swarm make it significantly easier to deploy, run, and update highly distributed, mission-critical applications. The orchestration engine automates many of the cumbersome tasks such as scaling up or down, asserting that the desired state is maintained at all times, and more.

But, the orchestration engine cannot just do everything automagically. Sometimes, we developers need to support the engine with some information that only we can know about. So, what do I mean by that?

Let's look at a single application service. Let's assume it is a microservice and let's call it service A. If we run service A containerized on a Kubernetes cluster, then Kubernetes can make sure that we have the five instances that we require in the service definition running at all times. If one instance...