Learn Docker - Fundamentals of Docker 19.x

574 Pages·2020·26.011 MB·English

by  Gabriel Schenker;

Learn Docker – Fundamentals
of Docker 19.x
Second Edition
Build, test, ship, and run containers with Docker and
Kubernetes
Gabriel N. Schenker
BIRMINGHAM - MUMBAI
Learn Docker – Fundamentals of Docker
19.x
Second Edition
Copyright © 2020 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form
or by any means, without the prior written permission of the publisher, except in the case of brief quotations
embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented.
However, the information contained in this book is sold without warranty, either express or implied. Neither the
author, nor Packt Publishing or its dealers and distributors, will be held liable for any damages caused or alleged to
have been caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products
mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy
of this information.
Commissioning Editor: Vijin Boricha
Acquisition Editor: Shrilekha Inani
Content Development Editor: Ronn Kurien
Senior Editor: Richard Brookes-Bland
Technical Editor: Sarvesh Jaywant
Copy Editor: Safis Editing
Project Coordinator: Neil Dmello
Proofreader: Safis Editing
Indexer: Tejal Daruwale Soni
Production Designer: Deepika Naik
First published: April 2018
Second edition: March 2020
Production reference: 1130320
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham
B3 2PB, UK.
ISBN 978-1-83882-747-2
www.packt.com
Packt.com
Subscribe to our online digital library for full access to over 7,000 books and videos, as well
as industry leading tools to help you plan your personal development and advance your
career. For more information, please visit our website.
Why subscribe?
Spend less time learning and more time coding with practical eBooks and Videos
from over 4,000 industry professionals
Improve your learning with Skill Plans built especially for you
Get a free eBook or video every month
Fully searchable for easy access to vital information
Copy and paste, print, and bookmark content
Did you know that Packt offers eBook versions of every book published, with PDF and
ePub files available? You can upgrade to the eBook version at www.packt.com and as a print
book customer, you are entitled to a discount on the eBook copy. Get in touch with us at
[email protected] for more details.
At www.packt.com, you can also read a collection of free technical articles, sign up for a
range of free newsletters, and receive exclusive discounts and offers on Packt books and
eBooks.
Contributors
About the author
Gabriel N. Schenker has more than 25 years of experience as an independent consultant,
architect, leader, trainer, mentor, and developer. Currently, Gabriel works as Lead Solution
Architect at Techgroup Switzerland. Prior to that, Gabriel worked as Lead Curriculum
Developer at Docker and at Confluent. Gabriel has a Ph.D. in Physics, and he is a Docker
Captain, a Certified Docker Associate, a Certified Kafka Developer and Operator, and an
ASP Insider. When not working, Gabriel enjoys time with his wonderful wife Veronicah
and his children.
I want to give special thanks to my editors, Ronn Kurien and Suzanne Coutinho, who
patiently helped me to get this book done and get it done right.
About the reviewer
Francisco Javier Ramírez Urea is a technology enthusiast and professional, Docker Captain,
casual developer, open source advocate, a certified trainer and solutions architect at
HoplaSoftware, and a technical book writer and reviewer.
He is also a Kubernetes Certified Administrator, a Docker Certified Associate, a Docker
Certified Instructor, and a Docker MTA program Consultant, as well as a
Docker/Kubernetes and NGINX expert and a DevOps/CI-CD solutions integrator.
He currently works as a solutions architect focused on containers and microservices
technologies. He is passionate to teach his students everything he know. Continuous
learning is the main motivation of his career.
Packt is searching for authors like you
If you're interested in becoming an author for Packt, please
visit authors.packtpub.com and apply today. We have worked with thousands of
developers and tech professionals, just like you, to help them share their insight with the
global tech community. You can make a general application, apply for a specific hot topic
that we are recruiting an author for, or submit your own idea.
Table of Contents
Preface 1
Section 1: Section 1: Motivation and Getting Started
Chapter 1: What Are Containers and Why Should I Use Them? 10
What are containers? 11
Why are containers important? 14
What's the benefit for me or for my company? 16
The Moby project 16
Docker products 17
Docker CE 17
Docker EE 18
Container architecture 18
Summary 19
Questions 20
Further reading 21
Chapter 2: Setting Up a Working Environment 22
Technical requirements 23
The Linux command shell 23
PowerShell for Windows 24
Using a package manager 24
Installing Homebrew on macOS 24
Installing Chocolatey on Windows 25
Installing Git 26
Choosing a code editor 27
Installing VS Code on macOS 27
Installing VS Code on Windows 28
Installing VS Code on Linux 28
Installing VS Code extensions 29
Installing Docker for Desktop 29
Installing Docker for Desktop on macOS 31
Installing Docker for Desktop on Windows 33
Installing Docker CE on Linux 34
Installing Docker Toolbox 34
Installing Docker Toolbox on macOS 35
Installing Docker Toolbox on Windows 36
Setting up Docker Toolbox 37
Installing Minikube 41
Table of Contents
Installing Minikube on macOS and Windows 41
Testing Minikube and kubectl 41
Summary 43
Questions 43
Further reading 44
Section 2: Section 2: Containerization, from Beginner to Black
Belt
Chapter 3: Mastering Containers 46
Technical requirements 47
Running the first container 47
Starting, stopping, and removing containers 49
Running a random trivia question container 51
Listing containers 53
Stopping and starting containers 55
Removing containers 57
Inspecting containers 57
Exec into a running container 59
Attaching to a running container 60
Retrieving container logs 62
Logging drivers 63
Using a container-specific logging driver 64
Advanced topic – changing the default logging driver 65
Anatomy of containers 66
Architecture 67
Namespaces 67
Control groups (cgroups) 69
Union filesystem (Unionfs) 70
Container plumbing 70
runC 70
Containerd 71
Summary 71
Questions 71
Further reading 71
Chapter 4: Creating and Managing Container Images 73
What are images? 74
The layered filesystem 74
The writable container layer 76
Copy-on-write 77
Graph drivers 78
Creating images 78
Interactive image creation 78
Using Dockerfiles 82
[ ii ]
Table of Contents
The FROM keyword 83
The RUN keyword 84
The COPY and ADD keywords 85
The WORKDIR keyword 86
The CMD and ENTRYPOINT keywords 87
A complex Dockerfile 89
Building an image 90
Multi-step builds 94
Dockerfile best practices 96
Saving and loading images 98
Lift and shift: Containerizing a legacy app 99
Analysis of external dependencies 100
Source code and build instructions 100
Configuration 101
Secrets 101
Authoring the Dockerfile 102
The base image 102
Assembling the sources 102
Building the application 103
Defining the start command 103
Why bother? 104
Sharing or shipping images 105
Tagging an image 105
Image namespaces 105
Official images 108
Pushing images to a registry 108
Summary 109
Questions 109
Further reading 110
Chapter 5: Data Volumes and Configuration 111
Technical requirements 112
Creating and mounting data volumes 112
Modifying the container layer 112
Creating volumes 113
Mounting a volume 116
Removing volumes 118
Accessing volumes created with Docker for Desktop 119
Sharing data between containers 122
Using host volumes 124
Defining volumes in images 126
Configuring containers 129
Defining environment variables for containers 130
Using configuration files 131
Defining environment variables in container images 133
Environment variables at build time 134
[ iii ]
Table of Contents
Summary 135
Questions 135
Further reading 136
Chapter 6: Debugging Code Running in Containers 137
Technical requirements 138
Evolving and testing code running in a container 138
Mounting evolving code into the running container 142
Auto restarting code upon changes 145
Auto-restarting for Node.js 145
Auto-restarting for Python 147
Auto-restarting for .NET 150
Line-by-line code debugging inside a container 155
Debugging a Node.js application 156
Debugging a .NET application 161
Instrumenting your code to produce meaningful logging
information 165
Instrumenting a Python application 166
Instrumenting a .NET C# application 168
Using Jaeger to monitor and troubleshoot 172
Summary 177
Questions 177
Further reading 178
Chapter 7: Using Docker to Supercharge Automation 179
Technical requirements 180
Executing simple admin tasks in a container 180
Using test containers 183
Integration tests for a Node.js application 186
The Testcontainers project 196
Using Docker to power a CI/CD pipeline 203
Summary 217
Questions 218
Further reading 218
Chapter 8: Advanced Docker Usage Scenarios 219
Technical requirements 220
All of the tips and tricks of a Docker pro 220
Keeping your Docker environment clean 220
Running Docker in Docker 221
Formatting the output of common Docker commands 224
Filtering the output of common Docker commands 225
Optimizing your build process 225
Limiting resources consumed by a container 227
Read-only filesystem 228
[ iv ]