Parse Markdown Front Matter with Terraform

frontmatter.tf

# Helper module for parsing front matter from a markdown file and returning
# the front matter content as a map.
#
# Usage:
#   module "frontmatter" {
#     source = "./path/to/modules/frontmatter"
#     content = file("path/to/markdown/file.md")
#   }
#
#   output "title_from_front_matter" {
#     value = module.frontmatter.map.title
#   }
#
variable "content" {
  description = "The content of the markdown file with front matter"
  type        = string
}

locals {
  # Replace newline characters with actual newlines for regex parsing
  content_with_newlines = replace(var.content, "\\n", "\n")

  # Use regex to match the front matter
  front_matter_matches = regexall("(?s)^---\n(.*?)\n---", local.content_with_newlines)

  # Extract the front matter content if found
  front_matter = length(local.front_matter_matches) > 0 ? local.front_matter_matches[0] : null

  # Debug: Output the raw front matter
  front_matter_raw = local.front_matter

  # Extract the front matter content without the delimiters if front matter is found
  front_matter_content = local.front_matter != null ? local.front_matter[0] : ""

  # Split the front matter into lines if content is not empty
  front_matter_lines = local.front_matter_content != "" ? split("\n", local.front_matter_content) : []

  # Parse each line into a map
  front_matter_map = length(local.front_matter_lines) > 0 ? {
    for line in local.front_matter_lines :
    split(":", line)[0] => trimspace(split(":", line)[1])
    if line != "" && can(split(":", line) && length(split(":", line)) > 1)
  } : {}
}

# Output the parsed front matter map
output "map" {
  value = local.front_matter_map
}

# Debug: Output the front matter content and lines
output "raw" {
  value       = local.front_matter_raw
  description = "The raw front matter content (for debugging)"
}

output "matches" {
  value       = local.front_matter_matches
  description = "The matches found in the content (for debugging)"
}


output "content" {
  value = local.front_matter_content
  description = "The content of the front matter (for debugging)"
}

output "lines" {
  value = local.front_matter_lines
  description = "The lines of the front matter content (for debugging)"
}