Merge Two TOML configuration files

toml-merge.py

import tomli
import tomli_w
import argparse
import os

if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("file1")
    parser.add_argument("file2")
    parser.add_argument("out_file")

    args = parser.parse_args()

    # print(args)

    # Check for input file existence
    file1, file2 = args.file1, args.file2
    out_path = args.out_file

    if not (os.path.exists(file1) and file1.endswith('toml')):
        raise ValueError(f'Invalid path {file1}')
    if not (os.path.exists(file2) and file2.endswith('toml')):
        raise ValueError(f'Invalid path {file2}')

    if os.path.isdir(out_path):
        output_parent_dir = out_path
        output_file = os.path.basename(file1)
    else:
        output_parent_dir = os.path.abspath(os.path.join(out_path, os.path.pardir))
        output_file = os.path.basename(out_path)

    os.makedirs(output_parent_dir, exist_ok=True)

    with open(file1, mode='rb') as stream:
        f1 = tomli.load(stream)

    with open(file2, mode='rb') as stream:
        f2 = tomli.load(stream)

    # print(f'{f1 = } \n {f2 = }')

    for key, val in f2.items():
        if not isinstance(val, dict):
            if key not in f1:
                f1.update({key: val})
            continue

        if key in f1:
            try:
                for key_, val_ in val.items():
                    if key_ not in f1[key]:
                        f1[key].update({key_: val_})
            except ValueError as e:
                raise ValueError(e)
        else:
            f1.update({key: val})

    with open(os.path.join(output_parent_dir, out_path), 'wb') as outfile:
        tomli_w.dump(f1, outfile)

Usage :

python toml-merge.py <base_file_path> <source_file_path> <out_path/dir>