A python script to convert JSON to HCL

json2hcl.py

#!/usr/bin/env python3
# json2hcl.py - Convert JSON to Terraform HCL

import json
import sys
import re
import argparse
from typing import Any, Dict, List, Union


def format_value(value: Any) -> str:
    """Format a value according to HCL syntax rules."""
    if isinstance(value, bool):
        return str(value).lower()
    elif isinstance(value, (int, float)):
        return str(value)
    elif isinstance(value, str):
        # Escape quotes and handle multiline strings
        escaped = value.replace("\\", "\\\\").replace('"', '\\"')
        if "\n" in escaped:
            return "<<EOT\n{}\nEOT".format(escaped)
        else:
            return f'"{escaped}"'
    elif value is None:
        return "null"
    else:
        raise ValueError(f"Unsupported type: {type(value)}")


def json_to_hcl(data: Union[Dict, List], indent: int = 0) -> str:
    """Convert a JSON object to HCL format."""
    result = []
    spaces = " " * indent

    if isinstance(data, dict):
        for key, value in data.items():
            if isinstance(value, dict):
                result.append(f"{spaces}{key} = {{")
                result.append(json_to_hcl(value, indent + 2))
                result.append(f"{spaces}}}")
            elif isinstance(value, list):
                if all(isinstance(item, dict) for item in value):
                    for item in value:
                        result.append(f"{spaces}{key} {{")
                        result.append(json_to_hcl(item, indent + 2))
                        result.append(f"{spaces}}}")
                else:
                    formatted_items = [format_value(item) for item in value]
                    result.append(f"{spaces}{key} = [{', '.join(formatted_items)}]")
            else:
                result.append(f"{spaces}{key} = {format_value(value)}")
    elif isinstance(data, list):
        if all(isinstance(item, dict) for item in data):
            for item in data:
                result.append(f"{spaces}{{")
                result.append(json_to_hcl(item, indent + 2))
                result.append(f"{spaces}}}")
        else:
            formatted_items = [format_value(item) for item in data]
            result.append(f"{spaces}[{', '.join(formatted_items)}]")

    return "\n".join(result)


def main():
    parser = argparse.ArgumentParser(description="Convert JSON to Terraform HCL")
    parser.add_argument(
        "input_file",
        nargs="?",
        type=argparse.FileType("r"),
        default=sys.stdin,
        help="Input JSON file (default: stdin)",
    )
    parser.add_argument(
        "output_file",
        nargs="?",
        type=argparse.FileType("w"),
        default=sys.stdout,
        help="Output HCL file (default: stdout)",
    )
    parser.add_argument(
        "-v", "--variable", help="Wrap output in a variable with the given name"
    )

    args = parser.parse_args()

    try:
        data = json.load(args.input_file)
        hcl = json_to_hcl(data)

        if args.variable:
            hcl = f"{args.variable} = {{\n{json_to_hcl(data, 2)}\n}}"

        args.output_file.write(hcl)
        args.output_file.write("\n")

    except json.JSONDecodeError as e:
        print(f"Error decoding JSON: {e}", file=sys.stderr)
        return 1
    except Exception as e:
        print(f"Error: {e}", file=sys.stderr)
        return 1
    finally:
        if args.input_file != sys.stdin:
            args.input_file.close()
        if args.output_file != sys.stdout:
            args.output_file.close()

    return 0


if __name__ == "__main__":
    sys.exit(main())
    
# Basic usage (read from file, output to stdout)
# python json2hcl.py input.json

# Read from stdin, output to file
# cat input.json | python json2hcl.py > output.tf

# Wrap in a variable
# python json2hcl.py input.json -v helm_values > output.tf

# Full example with input and output files
# python json2hcl.py input.json output.tf -v helm_values