Terraform: Up & Running: Writing Infrastructure as Code

365 Pages·2019·11.102 MB·English

by  Yevgeniy Brikman

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Terraform
Up & Running
Writing Infrastructure as Code
Yevgeniy Brikman

SECOND EDITION
Terraform: Up & Running
Writing Infrastructure as Code
Yevgeniy Brikman
BBeeiijjiinngg BBoossttoonn FFaarrnnhhaamm SSeebbaassttooppooll TTookkyyoo
Terraform: Up & Running
by Yevgeniy Brikman
Copyright © 2019 Yevgeniy Brikman. All rights reserved.
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September 2019: Second Edition
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2019-10-04: Second Release
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978-1-492-04690-5
[LSCH]
To Mom, Dad, Lyalya, and Molly

Table of Contents
Preface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
1. Why Terraform. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The Rise of DevOps 1
What Is Infrastructure as Code? 3
Ad Hoc Scripts 4
Configuration Management Tools 5
Server Templating Tools 7
Orchestration Tools 12
Provisioning Tools 14
The Benefits of Infrastructure as Code 15
How Terraform Works 17
How Terraform Compares to Other IaC Tools 19
Configuration Management Versus Provisioning 20
Mutable Infrastructure Versus Immutable Infrastructure 21
Procedural Language Versus Declarative Language 22
Master Versus Masterless 25
Agent Versus Agentless 26
Large Community Versus Small Community 28
Mature Versus Cutting Edge 30
Using Multiple Tools Together 31
Conclusion 33
2. Getting Started with Terraform. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Setting Up Your AWS Account 36
Install Terraform 39
Deploy a Single Server 40
Deploy a Single Web Server 48
v
Deploy a Configurable Web Server 55
Deploying a Cluster of Web Servers 61
Deploying a Load Balancer 64
Cleanup 73
Conclusion 74
3. How to Manage Terraform State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
What Is Terraform State? 76
Shared Storage for State Files 77
Limitations with Terraform’s Backends 85
Isolating State Files 87
Isolation via Workspaces 88
Isolation via File Layout 94
The terraform_remote_state Data Source 98
Conclusion 108
4. How to Create Reusable Infrastructure with Terraform Modules. . . . . . . . . . . . . . . . . . 109
Module Basics 112
Module Inputs 114
Module Locals 118
Module Outputs 120
Module Gotchas 123
File Paths 123
Inline Blocks 124
Module Versioning 126
Conclusion 132
5. Terraform Tips and Tricks: Loops, If-Statements, Deployment, and Gotchas. . . . . . . . 133
Loops 134
Loops with the count Parameter 134
Loops with for_each Expressions 140
Loops with for Expressions 147
Loops with the for String Directive 150
Conditionals 151
Conditionals with the count Parameter 151
Conditionals with for_each and for Expressions 161
Conditionals with the if String Directive 163
Zero-Downtime Deployment 163
Terraform Gotchas 175
count and for_each Have Limitations 175
Zero-Downtime Deployment Has Limitations 178
Valid Plans Can Fail 178
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Refactoring Can Be Tricky 180
Eventual Consistency Is Consistent…Eventually 183
Conclusion 184
6. Production-Grade Terraform Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
Why It Takes So Long to Build Production-Grade Infrastructure 187
The Production-Grade Infrastructure Checklist 189
Production-Grade Infrastructure Modules 191
Small Modules 191
Composable Modules 197
Testable Modules 205
Releasable modules 208
Beyond Terraform Modules 213
Conclusion 220
7. How to Test Terraform Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
Manual Tests 224
Manual Testing Basics 226
Cleaning Up After Tests 229
Automated Tests 231
Unit Tests 232
Integration Tests 261
End-to-End Tests 275
Other Testing Approaches 281
Conclusion 283
8. How to Use Terraform as a Team. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Adopting IaC in Your Team 286
Convince Your Boss 286
Work Incrementally 289
Give Your Team the Time to Learn 290
A Workflow for Deploying Application Code 292
Use Version Control 292
Run the Code Locally 293
Make Code Changes 293
Submit Changes for Review 294
Run Automated Tests 295
Merge and Release 296
Deploy 297
A Workflow for Deploying Infrastructure Code 301
Use Version Control 302
Run the Code Locally 306
Table of Contents | vii
Make Code Changes 307
Submit Changes for Review 308
Run Automated Tests 310
Merge and Release 312
Deploy 312
Putting It All Together 322
Conclusion 324
A. Recommended Reading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
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