Compliments of Microservice A r c h i t e c t u r e ALIGNING PRINCIPLES, PRACTICES, AND CULTUREIrakli Nadareishvili, Ronnie Mitra, Matt McLarty & Mike Amundsen Praise for Microservice Architecture The authors’ approach of starting with a value proposition, “Speed and Safety at Scale and in Harmony,” and reasoning from there, is an important contribution to thinking about application design. —Mel Conway, Educator and Inventor A well-thought-out and well-written description of the organizing principles underlying the microservices architectural style with a pragmatic example of applying them in practice. —James Lewis, Principal Consultant, ThoughtWorks This book demystifies one of the most important new tools for building robust, scalable software systems at speed. —Otto Berkes, Chief Technology Officer, CA Technologies If you’ve heard of companies doing microservices and want to learn more, Microservice Architecture is a great place to start. It addresses common questions and concerns about breaking down a monolith and the challenges you’ll face with culture, practices, and tooling. The microservices topic is a big one and this book gives you smart pointers on where to go next. —Chris Munns, Business Development Manager—DevOps, Amazon Web Services Anyone who is building a platform for use inside or outside an organization should read this book. It provides enough “a-ha” insights to keep everyone on your team engaged, from the business sponsor to the most technical team member. Highly recommended! —Dave Goldberg, Director, API Products, Capital One A practical roadmap to microservices design and the underlying cultural and organizational change that is needed to make it happen successfully. —Mark Boyd, Writer/Analyst, Platformable An essential guidebook for your microservices journey, presenting the concepts, discussions, and structures supportive of this architectural pattern as well as the pragmatic ground work to become successful. —Ian Kelly, Experimenter and Contributor, CA Technologies Microservice Architecture Aligning Principles, Practices, and Culture Irakli Nadareishvili, Ronnie Mitra, Matt McLarty, and Mike Amundsen Beijing Boston Farnham Sebastopol Tokyo Microservice Architecture by Irakli Nadareishvili, Ronnie Mitra, Matt McLarty, and Mike Amundsen Copyright © 2016 Mike Amundsen, Matt McLarty, Ronnie Mitra, Irakli Nadareishvili. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (http://safaribooksonline.com). For more information, contact our corporate/ institutional sales department: 800-998-9938 or [email protected] . Editors: Brian MacDonald and Holly Bauer Indexer: WordCo Indexing Services, Inc. Production Editor: Kristen Brown Interior Designer: David Futato Copyeditor: Christina Edwards Cover Designer: Karen Montgomery Proofreader: Kim Cofer Illustrator: Melanie Yarbrough June 2016: First Edition Revision History for the First Edition 2016-06-02: First Release See http://oreilly.com/catalog/errata.csp?isbn=9781491956250 for release details. The O’Reilly logo is a registered trademark of O’Reilly Media, Inc. Microservice Architecture, the cover image, and related trade dress are trademarks of O’Reilly Media, Inc. While the publisher and the authors have used good faith efforts to ensure that the information and instructions contained in this work are accurate, the publisher and the authors disclaim all responsibility for errors or omissions, including without limitation responsibility for damages resulting from the use of or reliance on this work. Use of the information and instructions contained in this work is at your own risk. If any code samples or other technology this work contains or describes is subject to open source licenses or the intellectual property rights of others, it is your responsibility to ensure that your use thereof complies with such licenses and/or rights. 978-1-491-95979-4 [LSI] Table of Contents Preface. xi Part I. Understanding Microservices 1. The Microservices Way. 3 Understanding Microservices 4 Adopting Microservices 5 “What are microservices? Don’t I already have them?” 6 “How could this work here?” 7 “How would we deal with all the parts? Who is in charge?” 8 The Microservices Way 9 The Speed of Change 9 The Safety of Change 9 At Scale 10 In Harmony 10 Summary 11 2. The Microservices Value Proposition. 13 Microservice Architecture Benefits 13 Deriving Business Value 15 Defining a Goal-Oriented, Layered Approach 17 Modularized Microservice Architecture 17 Cohesive Microservice Architecture 18 Systematized Microservice Architecture 18 Maturity Model for Microservice Architecture Goals and Benefits 19 Applying the Goal-Oriented, Layered Approach 20 Summary 21 vii Part II. Microservice Design Principles 3. Designing Microservice Systems. 25 The Systems Approach to Microservices 25 Service 27 Solution 28 Process and Tools 28 Organization 28 Culture 29 Embracing Change 29 Putting it Together: The Holistic System 30 Standardization and Coordination 30 A Microservices Design Process 33 Set Optimization Goals 34 Development Principles 35 Sketch the System Design 35 Implement, Observe, and Adjust 36 The Microservices System Designer 38 Summary 38 4. Establishing a Foundation. 41 Goals and Principles 42 Goals for the Microservices Way 42 Operating Principles 45 Platforms 49 Shared Capabilities 50 Local Capabilities 52 Culture 54 Focus on Communication 55 Aligning Your Teams 55 Fostering Innovation 56 Summary 58 Part III. Microservices in Practice 5. Service Design. 61 Microservice Boundaries 62 Microservice Boundaries and Domain-Driven Design 62 Bounded Context 64 Smaller Is Better 65 Ubiquitous Language 66 viii | Table of Contents API Design for Microservices 67 Messsage-Oriented 67 Hypermedia-Driven 68 Data and Microservices 70 Shipping, Inc. 70 Event Sourcing 72 System Model for Shipping, Inc. 75 CQRS 76 Distributed Transactions and Sagas 78 Asynchronous Message-Passing and Microservices 80 Dealing with Dependencies 81 Pragmatic Mobility 84 Summary 86 6. System Design and Operations. 89 Independent Deployability 89 More Servers, More Servers! My Kingdom for a Server! 91 Docker and Microservices 93 The Role of Service Discovery 94 The Need for an API Gateway 97 Security 97 Transformation and Orchestration 98 Routing 100 Monitoring and Alerting 101 Summary 101 7. Adopting Microservices in Practice. 103 Solution Architecture Guidance 104 How many bug fixes/features should be included in a single release? 104 When do I know our microservice transformation is done? 104 Organizational Guidance 105 How do I know if my organization is ready for microservices? 105 Culture Guidance 106 How do I introduce change? 106 Can I do microservices in a project-centric culture? 108 Can I do microservices with outsourced workers? 108 Tools and Process Guidance 109 What kinds of tools and technology are required for microservices? 109 What kinds of practices and processes will I need to support microservices? 110 How do I govern a microservice system? 111 Services Guidance 112 Table of Contents | ix Should all microservices be coded in the same programming language? 112 What do I do about orphaned components? 113 Summary 113 8. Epilogue. 115 A. Microservice Architecture Reading List. 117 Index. 121 x | Table of Contents Preface Microservice architecture has emerged as a common pattern of software develop‐ ment from the practices of a number of leading organizations. These practices includes principles, technologies, methodologies, organizational tendencies, and cul‐ tural characteristics. Companies taking steps to implement microservices and reap their benefits need to consider this broad scope. Who Should Read This Book You should read this book if you are interested in the architectural, organizational, and cultural changes that are needed to succeed with a microservice architecture. We primarily wrote this book for technology leaders and software architects who want to shift their organizations toward the microservices style of application development. You don’t have to be a CTO or enterprise architect to enjoy this book, but we’ve writ‐ ten our guidance under the assumption that you are able to influence the organiza‐ tional design, technology platform, and software architecture at your company. What’s In This Book This book promotes a goal-oriented, design-based approach to microservice architec‐ ture. We offer this design-centric approach because, as we talked to several companies about their programs, we discovered one of the keys to their success was the willing‐ ness to not stick to a single tool or process as they attempted to increase their compa‐ ny’s time-to-market while maintaining—even increasing—their systems’ safety and resilience. The companies we talked to offered a wide range of services including live video and audio streaming service, foundation-level virtual services in the cloud, and support for classic brick-and-mortar operations. While these companies’ products vary, we learned that the principles of speed and safety “at scale” were a common thread. They xi each worked to provide the same system properties in their own unique ways—ways that fit the key business values and goals of the company. It’s the properties and values that we focus on in this book, and the patterns and prac‐ tices we see companies employ in order to reach their unique