CODEWITHSUNDEEP
terraformterraform-provider-azure
Hound
Hound

Reputation: 927

Using terraform modules with in modules

We are working on creating various terraform modules for Azure cloud in our organization. I have a basic doubt on using these modules.

Lets say we have a module created for creating resource groups. When we write a module for storage container, Would it be better to use the resource group module inside the storage module itself or would it be better to let the user terraform script handle it specifying multiple module resource. Eg,

module resourcegroup {
…
}
module storage {
}

Thanks, Hound

Upvotes: 1

Views: 5546

Answers (1)

Martin Atkins
Martin Atkins

Reputation: 74045

What you're considering here is a design tradeoff rather than a question with a universal answer. With that said, the Terraform documentation section Module Composition recommends that you use only one level of module nesting where possible, and then have the root module connect the outputs from one module into the inputs of another.

One situation where you might decide to go against that advice and create multiple levels of nesting is when you want to write a module which intentionally constrains or raises the level of abstraction of another module written by someone else. Modules shared on Terraform Registry are often very general in order to serve various different use-cases, but those modules might also encapsulate some design best-practices for the system in question and so you might choose to wrap one or more of those general modules in a more specific module that more directly meets your use-case, and hopefully in turn make your "wrapper module" easier to use.

However, it's always important to keep in mind that although Terraform modules can in some sense encapsulate complexity, in the case of Terraform they can't truly hide that complexity the way we might expect for libraries in general-purpose languages, because the maintainer of the root module is ultimately responsible for understanding the full consequences of applying a plan, which involves reviewing all of the proposed changes even to resources encapsulated in nested modules.

Upvotes: 2

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