Understanding for_each in Terraform: Resolving Type List Issues with Module Variables

Dive into solutions for Terraform's `for_each` when working with a list of objects in modules. Learn how to convert lists to maps easily!
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Understanding for_each in Terraform: Resolving Type List Issues with Module Variables

When working with Terraform, especially within module directories, you may encounter challenges when trying to call a variable that is defined as a list(object) in a different directory. If you've seen an error related to the for_each argument while trying to use such a variable, you're not alone. In this post, we will break down the problem and offer a structured solution.

The Problem at Hand

You have a variable defined in your module as a list(object), specifically to define forwarded_ports. When you try to utilize this variable in a for_each loop, Terraform throws errors indicating that the argument provided is not a suitable type. Here’s a brief overview of the directory structure and relevant code:

Directory Structure

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Variables Definition

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Issue Encountered

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You faced errors indicating that your for_each value was unsuitable because it is a list of objects, whereas it should be a map or set of strings.

The Solution: Convert List to a Map

The key to resolving this issue lies in understanding that for_each requires a map or a set, not a list. Here’s how you can effectively convert your list to a map:

Conversion Code

You can change your for_each line from this:

[[See Video to Reveal this Text or Code Snippet]]

To this:

[[See Video to Reveal this Text or Code Snippet]]

Explanation

Here's a breakdown of what happens with this conversion:

Conclusion

When working with complex constructs like lists of objects in Terraform, it's crucial to pay attention to type requirements of constructs like for_each. By converting lists to maps, we ensure compatibility and can effectively iterate over our resources.

If you encounter similar issues in your Terraform projects, remember to check the types you are using and make the necessary conversions to avoid frustrating errors.

Happy Terraforming!