Terraform Nightmares: Hidden Pitfalls That Can Break Your Infrastructure (And How to Avoid Them!)

Why does Terraform sometimes feel like it has a mind of its own?

You write a simple module, run terraform apply, and suddenly, it wants to destroy half your infrastructure.

Or maybe you change an inline block, and Terraform insists on replacing a perfectly fine resource.

If you’ve been there, you’re not alone.

Terraform is powerful, but it also has some tricky concepts that can catch even experienced DevOps engineers off guard.

Let’s break down a few of these Terraform gotchas and how to avoid them.

1️⃣ Implicit vs. Explicit Dependencies (The “Why Is My Resource Not Ready?” Problem)

Terraform builds resources in parallel unless it knows they depend on each other. If your RDS instance is available but your app tries to connect before it’s fully initialized, you probably forgot to use depends_on.

🔸Fix it:

Terraform won’t guess dependencies – you have to tell it explicitly when needed!

2️⃣ Unexpected Resource Replacements (Why Is Terraform Destroying Everything?)

Ever modified an inline block (like security group rules) and Terraform wanted to replace the entire resource? This happens because Terraform treats some changes as destructive.