Infrastructure as Code, 3rd Edition

Chapter 9. Integrating Infrastructure Stacks

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As defined in Chapter 6, an infrastructure deployment stack is the smallest collection of infrastructure that can be changed independently. Chapter 7 described several design patterns that involve dividing the infrastructure resources for an environment across multiple stacks, to make it easier and safer to change and update parts of the system. However, as discussed in Chapter 5, multiple stacks will usually have dependencies between them. For example, if one stack creates shared networking structures like VPCs and subnets, another stack will need to provision its resources to use those networking structures.

This chapter describes several patterns for managing dependencies between infrastructure stacks. There are many popular techniques to implement discovery and integration of resources between stacks, but many of these techniques create tight coupling that makes changes more difficult. ...