Docker in Practice

384 Pages·2019·7.62 MB·english

by  Ian Miell

P
IN RACTICE

SECOND EDITION
Ian Miell
Aidan Hobson Sayers
M A N N I N G
Praise for the First Edition
A deluge of practical advice about applying Docker to problems you have right now.
—From the Foreword to the first edition by Ben Firshman, Docker, Inc.
Filled with 4-star recipes!
—Chad Davis, SolidFire
You'll love Docker after reading this book.
—José San Leandro, OSOCO
Packed with Docker tricks of the developer trade.
—Kirk Brattkus, Net Effect Technologies
Extremely good sets of tips for using docker. Really useful and pragmatic and
addresses real world docker issues.
—Amazon customer
Easy to read and follow. I have a much better understanding of the internal working
of Docker after reading this book.
—Amazon customer

Docker in Practice
S E
ECOND DITION
IAN MIELL
AIDAN HOBSON SAYERS
MANNING
Shelter Island
For online information and ordering of this and other Manning books, please visit
www.manning.com. The publisher offers discounts on this book when ordered in quantity.
For more information, please contact
Special Sales Department
Manning Publications Co.
20 Baldwin Road
PO Box 761
Shelter Island, NY 11964
Email: [email protected]
©2019 by Manning Publications Co. All rights reserved.
No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
any form or by means electronic, mechanical, photocopying, or otherwise, without prior written
permission of the publisher.
Many of the designations used by manufacturers and sellers to distinguish their products are
claimed as trademarks. Where those designations appear in the book, and Manning
Publications was aware of a trademark claim, the designations have been printed in initial caps
or all caps.
Recognizing the importance of preserving what has been written, it is Manning’s policy to have
the books we publish printed on acid-free paper, and we exert our best efforts to that end.
Recognizing also our responsibility to conserve the resources of our planet, Manning books are
printed on paper that is at least 15 percent recycled and processed without the use of elemental
chlorine.
Manning Publications Co. Development editor: Jenny Stout
20 Baldwin Road Review editor: Ivan Martinovic´
PO Box 761 Project manager: Vincent Nordhaus
Shelter Island, NY 11964 Copyeditor: Andy Carroll
Proofreader: Keri Hales
Technical proofreader: Jose San Leandro
Typesetter: Gordan Salinovic
Cover designer: Marija Tudor
ISBN 9781617294808
Printed in the United States of America
1 2 3 4 5 6 7 8 9 10 – SP – 24 23 22 21 20 19
contents
preface xiii
acknowledgments xv
about this book xvi
about the cover illustration xix
P 1 D ..........................................1
ART OCKER FUNDAMENTALS
1 Discovering Docker 3
1.1 The what and why of Docker 4
What is Docker? 5 ■ What is Docker good for? 7 ■ Key concepts 8
1.2 Building a Docker application 10
Ways to create a new Docker image 11 ■ Writing a Dockerfile 12
Building a Docker image 13 ■ Running a Docker container 14
Docker layering 16
2 Understanding Docker: Inside the engine room 19
2.1 Docker’s architecture 20
2.2 The Docker daemon 21
TECHNIQUE 1 Open your Docker daemon to the world 22
TECHNIQUE 2 Running containers as daemons 24
TECHNIQUE 3 Moving Docker to a different partition 27
v
vi CONTENTS
2.3 The Docker client 28
TECHNIQUE 4 Using socat to monitor Docker API traffic 28
TECHNIQUE 5 Using Docker in your browser 32
TECHNIQUE 6 Using ports to connect to containers 34
TECHNIQUE 7 Allowing container communication 35
TECHNIQUE 8 Linking containers for port isolation 37
2.4 Docker registries 39
TECHNIQUE 9 Setting up a local Docker registry 40
2.5 The Docker Hub 41
TECHNIQUE 10 Finding and running a Docker image 42
P 2 D ...................................45
ART OCKER AND DEVELOPMENT
3 Using Docker as a lightweight virtual machine 47
3.1 From VM to container 48
TECHNIQUE 11 Converting your VM to a container 48
TECHNIQUE 12 A host-like container 51
TECHNIQUE 13 Splitting a system into microservice containers 54
TECHNIQUE 14 Managing the startup of your container’s
services 57
3.2 Saving and restoring your work 59
TECHNIQUE 15 The “save game” approach: Cheap source
control 60
TECHNIQUE 16 Docker tagging 62
TECHNIQUE 17 Sharing images on the Docker Hub 65
TECHNIQUE 18 Referring to a specific image in builds 67
3.3 Environments as processes 68
TECHNIQUE 19 The “save game” approach: Winning at 2048 68
4 Building images 71
4.1 Building images 71
TECHNIQUE 20 Injecting files into your image using ADD 72
TECHNIQUE 21 Rebuilding without the cache 75
TECHNIQUE 22 Busting the cache 76
TECHNIQUE 23 Intelligent cache-busting using build-args 78
TECHNIQUE 24 Intelligent cache-busting using the ADD
directive 81
TECHNIQUE 25 Setting the right time zone in your containers 84
TECHNIQUE 26 Locale management 86
TECHNIQUE 27 Stepping through layers with the image-stepper 90
TECHNIQUE 28 Onbuild and golang 94
CONTENTS vii
5 Running containers 97
5.1 Running containers 97
TECHNIQUE 29 Running GUIs within Docker 98
TECHNIQUE 30 Inspecting containers 100
TECHNIQUE 31 Cleanly killing containers 101
TECHNIQUE 32 Using Docker Machine to provision Docker
hosts 103
TECHNIQUE 33 Wildcard DNS 107
5.2 Volumes—a persistent problem 108
TECHNIQUE 34 Docker volumes: Problems of persistence 108
TECHNIQUE 35 Distributed volumes with Resilio Sync 110
TECHNIQUE 36 Retaining your container’s bash history 112
TECHNIQUE 37 Data containers 114
TECHNIQUE 38 Remote volume mounting using SSHFS 116
TECHNIQUE 39 Sharing data over NFS 119
TECHNIQUE 40 Dev tools container 121
6 Day-to-day Docker 124
6.1 Staying ship-shape 124
TECHNIQUE 41 Running Docker without sudo 125
TECHNIQUE 42 Housekeeping containers 125
TECHNIQUE 43 Housekeeping volumes 127
TECHNIQUE 44 Detaching containers without stopping them 129
TECHNIQUE 45 Using Portainer to manage your Docker
daemon 130
TECHNIQUE 46 Generating a dependency graph of your Docker
images 131
TECHNIQUE 47 Direct action: Executing commands on your
container 133
TECHNIQUE 48 Are you in a Docker container? 134
7 Configuration management: Getting your house in order 137
7.1 Configuration management and Dockerfiles 138
TECHNIQUE 49 Creating reliable bespoke tools with
ENTRYPOINT 138
TECHNIQUE 50 Avoiding package drift by specifying versions 140
TECHNIQUE 51 Replacing text with perl -p -i -e 142
TECHNIQUE 52 Flattening images 143
TECHNIQUE 53 Managing foreign packages with Alien 145
7.2 Traditional configuration management tools with Docker 148
TECHNIQUE 54 Traditional: Using make with Docker 148
TECHNIQUE 55 Building images with Chef Solo 151
viii CONTENTS
7.3 Small is beautiful 155
TECHNIQUE 56 Tricks for making an image smaller 155
TECHNIQUE 57 Tiny Docker images with BusyBox and Alpine 157
TECHNIQUE 58 The Go model of minimal containers 159
TECHNIQUE 59 Using inotifywait to slim containers 162
TECHNIQUE 60 Big can be beautiful 164
P 3 D D O .........................................167
ART OCKER AND EV PS
8 Continuous integration: Speeding up your development
pipeline 169
8.1 Docker Hub automated builds 170
TECHNIQUE 61 Using the Docker Hub workflow 170
8.2 More efficient builds 173
TECHNIQUE 62 Speeding up I/O-intensive builds with
eatmydata 173
TECHNIQUE 63 Setting up a package cache for faster builds 175
TECHNIQUE 64 Headless Chrome in a container 178
TECHNIQUE 65 Running Selenium tests inside Docker 180
8.3 Containerizing your CI process 185
TECHNIQUE 66 Running the Jenkins master within a Docker
container 185
TECHNIQUE 67 Containing a complex development
environment 188
TECHNIQUE 68 Scaling your CI with Jenkins’ Swarm plugin 192
TECHNIQUE 69 Upgrading your containerized Jenkins server
safely 195
9 Continuous delivery: A perfect fit for Docker principles 200
9.1 Interacting with other teams in the CD pipeline 201
TECHNIQUE 70 The Docker contract: Reducing friction 201
9.2 Facilitating deployment of Docker images 204
TECHNIQUE 71 Manually mirroring registry images 204
TECHNIQUE 72 Delivering images over constrained
connections 206
TECHNIQUE 73 Sharing Docker objects as TAR files 208
9.3 Configuring your images for environments 210
TECHNIQUE 74 Informing your containers with etcd 210
9.4 Upgrading running containers 214
TECHNIQUE 75 Using confd to enable zero-downtime
switchovers 214
CONTENTS ix
10 Network simulation: Realistic environment testing without
the pain 220
10.1 Container communication: Beyond manual linking 221
TECHNIQUE 76 A simple Docker Compose cluster 221
TECHNIQUE 77 A SQLite server using Docker Compose 225
10.2 Using Docker to simulate real-world networking 229
TECHNIQUE 78 Simulating troublesome networks with
Comcast 230
TECHNIQUE 79 Simulating troublesome networks with
Blockade 233
10.3 Docker and virtual networks 237
TECHNIQUE 80 Creating another Docker virtual network 238
TECHNIQUE 81 Setting up a substrate network with Weave 241
P 4 O
ART RCHESTRATION FROM A SINGLE MACHINE TO
........................................................247
THE CLOUD
11 A primer on container orchestration 249
11.1 Simple single-host Docker 251
TECHNIQUE 82 Managing your host’s containers with
systemd 251
TECHNIQUE 83 Orchestrating the startup of your host’s
containers 254
11.2 Manual multi-host Docker 257
TECHNIQUE 84 Manual multi-host Docker with Helios 257
11.3 Service discovery: What have we here? 263
TECHNIQUE 85 Using Consul to discover services 264
TECHNIQUE 86 Automatic service registration with
Registrator 271
12 The data center as an OS with Docker 275
12.1 Multi-host Docker 276
TECHNIQUE 87 A seamless Docker cluster with swarm mode 276
TECHNIQUE 88 Using a Kubernetes cluster 280
TECHNIQUE 89 Accessing the Kubernetes API from within a
pod 285
TECHNIQUE 90 Using OpenShift to run AWS APIs locally 289
TECHNIQUE 91 Building a framework on Mesos 294
TECHNIQUE 92 Micromanaging Mesos with Marathon 302