How does Terraform access secret keys for authentication?

Terraform accesses secret keys for authentication in several ways, depending on the provider and environment settings:

• Through environment variables (e.g., AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY for AWS).
• Through configuration files or profiles (e.g., ~/.aws/credentials).
• Through built-in provider mechanisms, for example, for GCP — via service accounts and JSON key files.
• Through Vault or other secret storage integrated into the pipeline.

It is important not to store secrets directly in Terraform code, but to use external sources or environment variables for security. An example of using environment variables:

export AWS_ACCESS_KEY_ID="your_access_key"
export AWS_SECRET_ACCESS_KEY="your_secret_key"
terraform apply