How to create an SSH key in Terraform?

SSH keys are essential for secure access to servers and other resources. Terraform makes it easy to generate and manage SSH keys as part of your infrastructure code.

Why Use Terraform for SSH Keys?

By managing SSH keys in Terraform, you can:

• Automate key generation and distribution.
• Ensure consistent key management across environments.
• Integrate key management into your Infrastructure as Code workflow.

Generating an SSH Key in Terraform

Terraform provides the tls_private_key resource to generate SSH keys. Here's how to use it:

Example Configuration

resource "tls_private_key" "example" {
  algorithm = "RSA"
  rsa_bits  = 2048
}

output "private_key" {
  value = tls_private_key.example.private_key_pem
  sensitive = true
}

output "public_key" {
  value = tls_private_key.example.public_key_openssh
}

Explanation

• algorithm: Specifies the type of key to generate (e.g., RSA, ECDSA).
• rsa_bits: Defines the key length for RSA keys.
• private_key_pem: Outputs the private key in PEM format.
• public_key_openssh: Outputs the public key in OpenSSH format.

Applying the Configuration

Run the following commands to generate the SSH key:

terraform init
terraform apply

Terraform will generate the key pair and display the public key in the output. The private key is marked as sensitive and will not be displayed unless explicitly requested.

Using the SSH Key

You can use the generated SSH key to configure resources, such as EC2 instances:

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

  key_name = "example-key"

  provisioner "file" {
    source      = "local-file-path"
    destination = "/remote-path"

    connection {
      type        = "ssh"
      user        = "ec2-user"
      private_key = tls_private_key.example.private_key_pem
      host        = aws_instance.example.public_ip
    }
  }
}

Best Practices

• Store private keys securely, such as in a secrets manager.
• Use strong algorithms and key lengths for better security.
• Rotate keys regularly to minimize security risks.

By following these steps, you can efficiently generate and manage SSH keys in Terraform, ensuring secure access to your infrastructure.