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Learn how to effectively execute code in Terraform using conditional statements with `for_each`. We'll break down the solution to manage resources based on variable values.
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How to Use Conditional Statements in Terraform's for_each Loop

When writing Terraform code, you may encounter scenarios where you only want to execute a piece of code under certain conditions. This is commonly needed when you want to modify resource deployments based on variable values, ensuring your infrastructure is modular and adaptable.

In this guide, we’ll tackle a specific question on how to effectively utilize the for_each loop in Terraform with a conditional statement.

The Problem

Consider a specific use case where you want Terraform to execute a block of code that tags AWS resources — but only when a certain variable, such as myvar, equals "X". The following is the initial block of code you might have:

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

In this code, for_each is currently executing on all items in aws_eks_node_group.managed_workers. However, what if you only want it to run when myvar is X? Let's explore how you can achieve this.

The Solution

Goal

Our goal is to modify the for_each argument so that it only iterates through aws_eks_node_group.managed_workers when myvar is equal to "X".

Implementation

You can use the conditional expression by restructuring your code as follows:

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

Breakdown of the Solution

Conditional Checks:

The conditional expression var.myvar == "X" checks if the variable myvar holds the value "X".

for_each Assignment:

If the condition evaluates to true, for_each is assigned aws_eks_node_group.managed_workers, meaning the code block will run.

If the condition is false, it assigns an empty map {}, effectively skipping the execution of the resource.

Resource Definition:

Everything else inside the resource remains unchanged, ensuring that your infrastructure continues to be tagged correctly when the condition is met.

Conclusion

Conditionals can significantly enhance how you manage infrastructure with Terraform. By using a conditional in the for_each loop, you can control the deployment of resources based on variable states, thus increasing the flexibility and modularity of your Terraform scripts.

Feel free to implement this technique in your own Terraform projects to manage resources more effectively!



Now, you are equipped with the knowledge to use conditionals with for_each in Terraform. Happy coding!