Scenario

Terraform Scenario-Based Questions with Answers

1️⃣ How do you copy an existing AWS resource into Terraform?

✅ Use terraform import:

terraform import aws_instance.my_instance i-0abcd12345

---

2️⃣ How do you prevent accidental deletion of resources?

✅ Use prevent_destroy in lifecycle rules:

resource "aws_s3_bucket" "my_bucket" {
  bucket = "my-unique-bucket"

  lifecycle {
    prevent_destroy = true
  }
}

---

3️⃣ How do you handle sensitive data in Terraform?

✅ Use environment variables or terraform.tfvars and vault integration.

export TF_VAR_db_password="supersecret"

✅ Use sensitive = true in outputs:

output "db_password" {
  value     = aws_db_instance.mydb.password
  sensitive = true
}

---

4️⃣ How do you provision multiple resources dynamically?

✅ Use count or for_each:

resource "aws_instance" "web" {
  count         = 3
  ami           = "ami-123456"
  instance_type = "t2.micro"
}

---

5️⃣ How do you rollback changes in Terraform?

✅ Use a previous state file backup:

mv terraform.tfstate.backup terraform.tfstate
terraform apply

---

6️⃣ How do you deploy resources in multiple environments?

✅ Use workspaces:

terraform workspace new dev
terraform workspace select dev
terraform apply

---

7️⃣ How do you reference outputs from another module?

✅ Use module.<module_name>.<output_name>:

output "vpc_id" {
  value = module.vpc.vpc_id
}

---

8️⃣ How do you update a Terraform module without breaking infrastructure?

✅ Run:

terraform get -update
terraform apply

---

9️⃣ How do you avoid storing credentials in Terraform code?

✅ Use AWS CLI credentials or Vault. ✅ Use environment variables:

export AWS_ACCESS_KEY_ID="your_key"
export AWS_SECRET_ACCESS_KEY="your_secret"

---

🔟 How do you apply changes to a specific resource?

✅ Use -target:

terraform apply -target=aws_instance.web

---

1️⃣1️⃣ How do you ensure resources are created in a specific order?

✅ Use depends_on:

resource "aws_instance" "app" {
  depends_on = [aws_db_instance.mydb]
}

---

1️⃣2️⃣ How do you debug Terraform errors?

✅ Enable logs:

TF_LOG=DEBUG terraform apply

---

1️⃣3️⃣ How do you set default values for variables?

✅ Use default:

variable "instance_type" {
  type    = string
  default = "t3.medium"
}

---

1️⃣4️⃣ How do you test Terraform changes before applying?

✅ Use terraform plan:

terraform plan

---

1️⃣5️⃣ How do you migrate Terraform state to S3?

✅ Configure backend:

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

✅ Then run:

terraform init -migrate-state

---

1️⃣6️⃣ How do you dynamically get the latest AMI for EC2?

✅ Use data "aws_ami":

data "aws_ami" "latest_ami" {
  most_recent = true
  owners      = ["amazon"]
}

---

1️⃣7️⃣ How do you delete a specific resource without affecting others?

✅ Use terraform destroy -target:

terraform destroy -target=aws_s3_bucket.my_bucket

---

1️⃣8️⃣ How do you use remote modules in Terraform?

✅ Use source in the module:

module "vpc" {
  source = "git::https://github.com/user/repo.git//modules/vpc"
}

---

1️⃣9️⃣ How do you perform drift detection in Terraform?

✅ Run:

terraform plan

✅ Use terraform refresh to update the state file.

---

2️⃣0️⃣ How do you rename a resource in Terraform without recreation?

✅ Use terraform state mv:

terraform state mv aws_instance.old_name aws_instance.new_name

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🚀 Final Thoughts

These scenario-based questions will help you demonstrate real-world expertise in Terraform during an interview. Let me know if you need more advanced scenarios!