Most engineers assume modules make Terraform safer.
That assumption is wrong.
Modules can hide behavior, expand blast radius, and create identity instability inside state.
A single input change can trigger unrelated resource changes across your environment.
This lesson breaks down the exact failure modes:
- God modules that combine unrelated systems
- Pass-through inputs that remove abstraction safety
- Hidden naming that forces resource replacement
- Provider misplacement that risks wrong account deployment
Terraform does exactly what the graph tells it to do.
Bad module design corrupts that graph.
If you understand these anti-patterns, you control the system.