Book Image

Learning Docker - Second Edition

By : Vinod Singh, Pethuru Raj, Jeeva S. Chelladhurai
Book Image

Learning Docker - Second Edition

By: Vinod Singh, Pethuru Raj, Jeeva S. Chelladhurai

Overview of this book

Docker is an open source containerization engine that offers a simple and faster way for developing and running software. Docker containers wrap software in a complete filesystem that contains everything it needs to run, enabling any application to be run anywhere – this flexibily and portabily means that you can run apps in the cloud, on virtual machines, or on dedicated servers. This book will give you a tour of the new features of Docker and help you get started with Docker by building and deploying a simple application. It will walk you through the commands required to manage Docker images and containers. You’ll be shown how to download new images, run containers, list the containers running on the Docker host, and kill them. You’ll learn how to leverage Docker’s volumes feature to share data between the Docker host and its containers – this data management feature is also useful for persistent data. This book also covers how to orchestrate containers using Docker compose, debug containers, and secure containers using the AppArmor and SELinux security modules.
Table of Contents (13 chapters)

The Dockerfile build instructions

So far, we have looked at the integrated build system, the Dockerfile syntax, and a sample life cycle, wherein we discussed how a sample Dockerfile is leveraged for generating an image and how a container gets spun off from that image. In this section, we will introduce the Dockerfile instructions, their syntax, and a few befitting examples.

The FROM instruction

The FROM instruction is the most important one and is the first valid instruction of a Dockerfile. It sets the base image for the build process. Subsequent instructions will use this base image and build on top of it. The Docker build system lets you flexibly use the images built by anyone. You can also extend them by adding more precise and practical features. By default...