Terramate — IaC Orchestration for Terraform & OpenTofu

What it is

Terramate is an open-source orchestration tool that extends Terraform and OpenTofu with stack management, code generation, change detection, and drift detection. It helps teams scale from a single Terraform directory to hundreds of stacks by managing dependencies, ordering execution, and detecting which stacks actually changed.

Terramate targets platform and infrastructure engineers managing large Terraform codebases. If your Terraform project has grown into many modules and environments with complex interdependencies, Terramate brings structure without replacing your existing HCL.

How it saves time or tokens

This workflow provides installation and initialization commands. Instead of running terraform apply across every directory manually, Terramate detects which stacks changed and runs only those. Code generation eliminates copy-paste between stacks, and drift detection alerts you to manual changes.

How to use

1. Install Terramate:

brew install terramate

1. Initialize in an existing Terraform repo:

terramate create --name my-stack

1. Run Terraform through Terramate:

# Detect changed stacks and run plan only on those
terramate run --changed -- terraform plan

# Apply across all stacks in dependency order
terramate run -- terraform apply -auto-approve

# Check for drift
terramate run -- terraform plan -detailed-exitcode

Example

# terramate.tm.hcl - Stack configuration
stack {
  name        = "production-vpc"
  description = "Production VPC and networking"
  tags        = ["network", "production"]
}

# Generate shared backend config across stacks
generate_hcl "_backend.tf" {
  content {
    terraform {
      backend "s3" {
        bucket = "my-terraform-state"
        key    = "stacks/${terramate.stack.path.relative}/terraform.tfstate"
        region = "us-east-1"
      }
    }
  }
}

# Run only on stacks tagged 'production'
terramate run --tags production -- terraform plan

Related on TokRepo

• DevOps tools -- Infrastructure automation and management
• Automation tools -- Workflow automation for operations teams

Common pitfalls

• Terramate does not replace Terraform. It wraps and orchestrates it. Your existing .tf files remain unchanged; Terramate adds .tm.hcl files for stack configuration.
• Change detection works with Git. Uncommitted changes are not detected by default. Commit your changes or use --changed with appropriate flags.
• Code generation templates use Terramate's own HCL syntax, not standard Terraform. Review the Terramate docs for template variables and functions.