Terraform Expressions

📋 Today I have completed Terraform expression, its types and use cases with practical hands-on.

📌What is terraform expression?

1. Help us to avoid rewriting the code again and again, make configurations dynamic, reusable, and smart.

✅ Types:

📌 Conditional expression:

1. Evaluates a condition and returns one of two values based on whether the condition is true or false.

Syntax:
Condition ? True_value : false_value

Eg:

Output:

📌 Dynamic Blocks:

1. It will used when you want to create repeated nested blocks automatically, instead of writing them manually.
2. It’s like a loop (for-each) inside a resource block and will create one block for each item in a list or map.

Syntax:
dynamic "block_name" {
for_each = var.collection
content {
# Block configuration using each.key and each.value
}
}

🔁 How it works:

1. for_each iterates over a list or map
2. content defines what each block should contain
3. Access values using block_name.value or block_name.key

Eg:
main.tf:

variable.tf:

Output:

🌀 Use Cases:

1. Security group rules
2. Multiple EBS volumes on EC2 instances
3. Route table routes
4. IAM policies
5. Kubernetes containers
6. CloudFront behaviors
7. Tags
8. Environment variables

📌 Splat Expression:

1. Let's you get a list of values from multiple resources created using count or for_each.
2. It’s like saying “give me this attribute from ALL the resources.”

Syntax:
resource_list[*].attribute_name

Eg:

Gives the instance ids from nandan_ec2 instances.

Refer: https://youtu.be/R4ShnFDJwI8?si=rlAMgR-JZjdd6djf

Thanks to Piyush, The Cloud Community