How to Prevent Multiple Terraform Apply

When multiple DevOps engineers work on the same Terraform configuration, it’s crucial to prevent simultaneous terraform apply commands to avoid conflicts and infrastructure inconsistencies.

🔹 Solution: Use Terraform State Locking

Terraform state locking ensures that only one person can run terraform apply at a time. This is best achieved using remote backends like:
✔ AWS S3 + DynamoDB
✔ Terraform Cloud

🔹 How to Implement State Locking with AWS S3 & DynamoDB

1️⃣ Create an S3 bucket for state storage:

"aws_s3_bucket" "terraform_state" {
  bucket = "my-terraform-state-bucket"
  versioning {
    enabled = true
  }
}

2️⃣ Create a DynamoDB table for locking:

"aws_dynamodb_table" "terraform_locks" {
  name         = "terraform-state-lock"
  billing_mode = "PAY_PER_REQUEST"
  hash_key     = "LockID"
  attribute {
    name = "LockID"
    type = "S"
  }
}

3️⃣ Configure the backend in Terraform:

terraform {
  backend "s3" {
    bucket         = "my-terraform-state-bucket"
    key            = "terraform.tfstate"
    region         = "us-east-1"
    dynamodb_table = "terraform-state-lock"
    encrypt        = true
  }
}

✅ Now, only one engineer can run terraform apply at a time!