Terraform Files Explained: main.tf, variables.tf, outputs.tf, and terraform.tfvars

Terraform Files Explained#

Learn the purpose of main.tf , variables.tf , outputs.tf , terraform.tfvars , and other common Terraform files used in real projects.

Quick answer#

main.tf#

Main resources, providers, and infrastructure definitions.

variables.tf#

Input variables used to make configuration reusable.

outputs.tf#

Values Terraform should show after apply.

terraform.tfvars#

Environment-specific values for variables.

Common Terraform project structure#

terraform-project/ main.tf variables.tf outputs.tf terraform.tfvars versions.tf providers.tf

main.tf example#

resource "random_pet" "server" { length = 2 }

variables.tf example#

variable "environment" { type = string description = "Deployment environment" default = "dev" }

outputs.tf example#

output "server_name" { value = random_pet.server.id }

terraform.tfvars example#

environment = "staging"

Best practices#

• Keep file names predictable.
• Do not put secrets in tfvars files committed to Git.
• Use variables for values that change by environment.
• Use outputs for values needed by users or other systems.
• Use versions.tf for Terraform and provider version constraints.

Related guides#

• Terraform Learning Path
• Terraform Providers Explained