Format Engine (fmt)¶

The format engine ensures consistent formatting across your Terraform and Terragrunt files.

Overview¶

The fmt engine uses the HCL formatter to standardize code formatting, similar to terraform fmt but with additional capabilities.

Usage¶

# Format all files
terratidy fmt

# Check formatting without changes
terratidy fmt --check

# Show diff of changes
terratidy fmt --diff

# Format only changed files
terratidy fmt --changed

# Format and apply style fixes
terratidy fmt --all

fmt vs style --fix vs fmt --all¶

TerraTidy provides different commands for different formatting needs:

• fmt: Applies HCL formatting rules (indentation, alignment, spacing). This is equivalent to terraform fmt.
• style --fix: Applies TerraTidy style rules (naming conventions, block ordering, file organization) without HCL formatting.
• fmt --all: Combines both - first formats files, then applies style fixes. Use this when you want complete code cleanup.

Configuration¶

engines:
  fmt:
    enabled: true
    config:
      # No additional config needed - uses HCL defaults

What Gets Formatted¶

• Indentation (2 spaces)
• Attribute alignment
• Block spacing
• Trailing whitespace removal
• Consistent line endings

Example¶

Before:

resource "aws_instance" "example" {
ami = "ami-12345"
  instance_type="t2.micro"
    tags={
Name="example"
  }
}

After:

resource "aws_instance" "example" {
  ami           = "ami-12345"
  instance_type = "t2.micro"
  tags = {
    Name = "example"
  }
}

Integration with CI/CD¶

Use --check in CI to fail if files need formatting:

- name: Check formatting
  run: terratidy fmt --check