Day 10: Making Terraform Smarter with Conditions, Dynamic Blocks, and Splat Expressions

#devops #tutorial #terraform

Day 10 was one of those days where Terraform started to feel less like static configuration and more like real logic. Until now, I was mostly writing fixed resources. Today, I learned how to make Terraform react to conditions, generate blocks dynamically, and handle multiple resources cleanly.

This session focused on three important concepts: conditional expressions, dynamic blocks, and splat expressions.

Conditional Expressions in Terraform

Conditional expressions help Terraform make decisions based on values. Instead of writing separate resources for different environments, we can control behavior using conditions.

The basic format looks like this:

condition ? true_value : false_value

Dynamic Blocks: Writing Less, Doing More

Dynamic blocks were one of the most interesting parts of today’s learning. They allow Terraform to generate repeated blocks automatically, instead of writing the same configuration multiple times.

This is especially useful when a resource has nested blocks like ingress rules or tags.

Example:

dynamic "ingress" {
  for_each = var.ingress_rules
  content {
    from_port   = ingress.value.from
    to_port     = ingress.value.to
    protocol    = ingress.value.protocol
    cidr_blocks = ingress.value.cidr
  }
}

What I liked about this is how clean the configuration becomes. Instead of repeating the same block again and again, Terraform handles it in a loop-like way.

Dynamic blocks make the code:
Easier to maintain
Less repetitive
More flexible

Splat Expressions: Working with Multiple Resources

Splat expressions are used when multiple resources are created and we want to access their attributes together.

Example

aws_instance.example[*].id

This returns a list of all instance IDs created under that resource.

Splat expressions are very helpful when:

Using count or for_each
Passing multiple values to outputs
Avoiding manual indexing

It made my code feel cleaner and easier to understand.

What I Understood After Practicing

Before today, I was writing Terraform in a very fixed way. After learning these concepts:

Conditional expressions helped reduce duplicate code
Dynamic blocks simplified repeated configurations
Splat expressions made handling multiple resources easier
Terraform felt more logical and flexible

Hands-on practice made these concepts much clearer than just reading about them.

Key Takeaways from Day 10

Terraform supports conditional logic
Dynamic blocks reduce repetition
Splat expressions simplify multi-resource outputs
These features make Terraform more scalable
Clean logic leads to clean infrastructure code

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