Скачать или смотреть How to Populate New Output Variables in Your Terraform State File

Learn how to effectively manage output variables in Terraform states, ensuring that your infrastructure configurations remain updated and consistent.
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How to Populate New Output Variables in Your Terraform State File

When working with Terraform, you may encounter situations where you need to expose new output variables in your state file. A common scenario arises when you want to pass information from one module to another, ensuring that configurations remain consistent and reusable. In this guide, we will tackle the issue of populating output variables effectively and guide you through the solution step by step.

Understanding the Problem

In your Terraform configuration, you may define variables that you want to share between modules. For instance, you have set up a list of email addresses as follows:

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

When attempting to retrieve this variable in a subfolder module using the terraform_remote_state, you might notice that after running terraform plan or terraform apply, Terraform reports "No changes. Infrastructure is up-to-date." This indicates that your new outputs have not been committed to the state, leaving you with no accessibility to those variables in your desired module.

The Solution: Updating Output Management

Step 1: Understand Terraform Versions

Before applying any changes, it is essential to note that behavior varies across different Terraform versions. In Terraform versions 0.12 and earlier, output changes aren't treated as actionable changes for apply commands. Therefore, you won't see any updates to your state file without sufficient resource updates.

Step 2: Utilize Terraform Refresh

One way to populate new outputs without making resource changes is to use the terraform refresh command. This command will resynchronize the state file with the remote objects. However, be cautious; running terraform refresh can also lead to unintended updates in other parts of your state.

Step 3: Upgrade to Terraform 0.13 and Above

The best approach, especially if you frequently work with output values, is to upgrade to Terraform 0.13 or later. Terraform has improved how output values are handled in this version—changes to output values are recognized and can be planned and applied similarly to resource modifications. Here’s how to proceed:

Add/Update the Output Blocks: In your main module, ensure that you define output blocks for the variables you wish to share. For your example, you may include:

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

Run Terraform Commands: Use the following commands to apply your changes:

Run terraform plan to preview the effect of your updates.

Execute terraform apply to commit these changes into your state file.

By following this workflow, you can seamlessly add or update outputs and have them reflected in your Terraform state file.

Conclusion

Effectively managing output variables across various modules in Terraform is critical for maintaining a modular and reusable infrastructure codebase. By understanding the methods to populate new output variables and staying updated with the latest Terraform features, you can ensure that your configurations are both functional and easily manageable.

If you have any questions or need further clarification on handling Terraform state files, feel free to reach out in the comments below!