Infrastructure as Code: Mistakes I Made So You Don't Have To

# Infrastructure as Code: Mistakes I Made So You Don't Have To

After managing infrastructure with Terraform for years, I've made every mistake in the book. Here are the ones that hurt the most.

1. Hardcoding Everything

*The Mistake:** My first Terraform config looked like this:

hcl

resource "aws_instance" "web" {
  ami           = "ami-12345678"
  instance_type = "t2.micro"
}

Seems fine until you need to deploy to another region or environment.

*The Fix:** Use variables and data sources:

hcl

data "aws_ami" "ubuntu" {
  most_recent = true
  filter {
    name   = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-*"]
  }
}

resource "aws_instance" "web" {

  ami           = data.aws_ami.ubuntu.id
  instance_type = var.instance_type
}

2. Not Using Remote State

*The Mistake:** Keeping `terraform.tfstate` locally. Lost my state file once. Never again.

*The Fix:** Always use remote state:

hcl

terraform {
  backend "s3" {
    bucket = "my-terraform-state"
    key    = "prod/terraform.tfstate"
    region = "us-east-1"
  }
}

Enable versioning on that S3 bucket. Trust me.

3. Massive Monolithic Configs

*The Mistake:** One giant `main.tf` with 2000 lines. Good luck finding anything.

*The Fix:** Break it up:
`main.tf` - Main resources
`variables.tf` - Input variables
`outputs.tf` - Output values
`versions.tf` - Provider versions
Separate modules for reusable components

4. Not Locking Provider Versions

*The Mistake:**

hcl

provider "aws" {
  region = "us-east-1"
}

Provider updates, breaks everything. Classic.

*The Fix:**

hcl

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 4.0"
    }
  }
}

5. Destroying Production by Accident

*The Mistake:** Running `terraform destroy` in the wrong terminal window. We've all been there.

*The Fix:**
Use workspace prefixes in your terminal
Add lifecycle prevent_destroy blocks:

hcl

resource "aws_instance" "critical" {
  # ...
  lifecycle {
    prevent_destroy = true
  }
}

Use Terraform Cloud with proper RBAC

Lessons Learned

Infrastructure as Code is powerful, but it's also dangerous. Treat your Terraform code like production code because it literally creates your production.

My golden rules:
Always use remote state
Lock your provider versions
Use modules for reusability
Test in dev first (obvious but ignored)
Plan before apply, always

Made any catastrophic Terraform mistakes? You're not alone. Share yours!