Book Image

Docker Quick Start Guide

By : Earl Waud
Book Image

Docker Quick Start Guide

By: Earl Waud

Overview of this book

Docker is an open source software platform that helps you with creating, deploying, and running your applications using containers. This book is your ideal introduction to Docker and containerization. You will learn how to set up a Docker development environment on a Linux, Mac, or Windows workstation, and learn your way around all the commands to run and manage your Docker images and containers. You will explore the Dockerfile and learn how to build your own enterprise-grade Docker images. Then you will learn about Docker networks, Docker swarm, and Docker volumes, and how to use these features with Docker stacks in order to define, deploy, and maintain highly-scalable, fault-tolerant multi-container applications. Finally, you will learn how to leverage Docker with Jenkins to automate the building of Docker images and the deployment of Docker containers. By the end of this book, you will be well prepared when it comes to using Docker for your next project.
Table of Contents (10 chapters)

The SHELL instruction

As you have read in many sections throughout this chapter, there are several instructions that take two forms, the exec form or the shell form. As mentioned, the default used by all of the shell forms is ["/bin/sh", "-c"] for Linux containers, and ["cmd", "/S", "/C"] for Windows containers. The SHELL instruction allows you to change that default. Here is the syntax for the SHELL instruction:

# SHELL instruction syntax
SHELL ["executable", "parameters"]

The SHELL instruction can be used more than once in a Dockerfile. All instructions that use a shell, and that come after a SHELL instruction, will use the new shell. Thus, you can change the shell multiple times in a single Dockerfile as needed. This can be especially powerful when creating Windows containers since it allows you to switch...