How to dynamically pass an AMI variable into Terraform's AWS EC2 instances

Learn how to seamlessly integrate variable AMIs in your Terraform configurations for AWS EC2 instances, ensuring dynamic deployment based on your requirements.
---

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Variable AMI Integration in Terraform

The Problem: Concatenating Variables with Terraform Syntax

In your initial attempt, you used the following line to assign the AMI based on a variable:

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

However, this syntax is invalid in Terraform. The error messages indicate that Terraform does not recognize concatenations with variable dots in this context. Consequently, you were unable to pass the variable to dynamically select the corresponding AMI.

The Solution: Leveraging for_each

To tackle this problem, we can utilize the for_each function when defining our aws_ami data sources. Below is a well-structured solution that outlines how to implement this approach effectively:

Step 1: Define Local Allowed Operating Systems

First, we will create a local variable to hold the configurations for different operating systems. This will include both the owner ID and the filter used to find the appropriate AMI.

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

Step 2: Create a Variable for AMI Name

Next, we define a variable that allows users to select the desired AMI. To enhance this, we'll include validation to limit input to the specified operating systems.

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

Step 3: Define the aws_ami Resource Using for_each

Here, we apply for_each to create a data source for each AMI configuration. This method allows us to access AMI data dynamically based on the provided operating system name.

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

Step 4: Configure the AWS Instance Resource

Finally, we can set the AMI for our AWS instance resource, utilizing the variable to specify which AMI to use based on the user input.

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

Conclusion

By following the above steps, you can now dynamically select AMIs based on user-defined variables in your Terraform configurations. The use of the for_each functionality allows for a scalable and maintainable approach, enabling you to expand supported operating systems simply by updating the local variable. This means easier management and flexibility when provisioning your EC2 instances!

Feel free to explore, customize, and expand upon this structure to fit your infrastructure needs!