Introduction

Terraform relies on its state file to maintain the infrastructure. The state file is a crucial component of Terraform's functionality that stores the current state of your infrastructure managed by Terraform. this file is a HCL formatted file that contains current state, like dependencies, and metadata.

Example

In the Terraform lifecycle, initiating terraform apply triggers changes to the infrastructure and creates a state file (terraform.tfstate) to record the current state. When updating existing resources, Terraform references this state file to ensure consistency. If modifications are necessary, Terraform applies them accordingly. Conversely, without the state file, Terraform would create new resources instead of updating existing ones. Therefore, the state file serves as a record of the infrastructure and guides Terraform actions, including destruction when needed.

Advantages

Resource Tracking

Terraform uses the state file to identify resources provisioned in the infrastructure. This helps Terraform to track and manage resources accurately, as infrastructure changes over time.

Concurrency control

Terraform uses locks within the state file to prevent multiple users or processes from modifying the infrastructure simultaneously, by reducing the of conflicts and errors.

Plan Calculation

Terraform uses the state file to calculate and display the difference between the desired configuration (defined in your Terraform code) and the current infrastructure state. This helps you understand what changes Terraform will make before applying them.

Resource Metadata

The state file stores metadata about each resource, such as unique identifiers, which is crucial for managing resources and understanding their relationships.

Disadvantages

Difficulty in Managing Secrets

VCS platforms are not designed to handle secrets securely. Storing secrets directly in Terraform state files within VCS can pose a security risk, as these secrets may be inadvertently exposed or leaked.

Security Risks

Terraform state files may contain sensitive information such as resource IDs, IP addresses, or access keys. Storing these files in VCS can expose this sensitive information to unauthorized access if proper security measures are not in place, potentially leading to security breaches.

Versioning Complexity

Managing state files in VCS can lead to complex versioning issues, especially when multiple team members are working on the same infrastructure.

Lack of State Locking

VCS platforms do not provide built-in locking mechanisms to prevent concurrent modifications to the Terraform state file. Without proper locking, simultaneous Terraform executions by multiple users or automation processes can lead to race conditions and inconsistencies in the state file.

Overcoming Disadvantages

Remote Backends

Terraform allows users to store statefile in remote repository like Terraform Cloud, S3, Azure Blob Storage, Hashicorp Vault etc rather than storing them in VCS. They can serve as the remote backend for better reliability and scalability, users can benefit from improved security measures, such as restricting access to the bucket using AWS Identity and Access Management (IAM) rules. This ensures that only authorized individuals or processes can access and modify the state file. Adopting the remote backend enables automatic synchronization of the state file.

Here is a way to configure remote backends.

Example

terraform {
  backend "remote" {
    hostname = "app.terraform.io"
    organization = "company"

    workspaces {
      name = "my-app-prod"
    }
  }
}

Conclusion

In conclusion, Terraform's state file is crucial for managing infrastructure. It helps track resources, control changes, and plan updates. However storing it in version control systems can pose security and versioning challenges. Fortunately, using remote backends like Terraform Cloud or S3 addresses these issues by enhancing security and enabling automatic syncing. In short, while the state file is vital, remote backends offer a safer and more efficient solution for infrastructure management.