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)

Working with Docker images

In the previous chapter, we demonstrated the typical Hello World example using the
hello-world image. Now, there is a need for a closer observation of the output of the docker pull subcommand, which is the de facto command to download Docker images. Now, in this section, we will use the busybox image, one of the smallest but a very handy Docker image, to dive deep into Docker image handling:

If you pay close attention to the output of the docker pull subcommand, you will notice the Using default tag: latest text. The Docker image management capability (the local image storage on your Docker host or on a Docker image registry) enables storing multiple variants of the Docker image. In other words, you could use tags to version your images.

By default, Docker always uses the image that is tagged as latest. Each image variant can be directly identified by qualifying it with an appropriate...