merge.py

#!/usr/bin/env python3

import os
from sys import argv
from shutil import copyfile
import yaml

def yamlLoader(file):
    with open(file, 'r') as f:
        return yaml.safe_load(f)

def patchConfig(mainConfigFile, patchfiles):
    config = yamlLoader(mainConfigFile)

    # patch in config snippets from config.d
    for file in patchFiles:
        patch = yamlLoader(file)
        config.update(patch)

    # make a backup of the original config
    copyfile(mainConfigFile, mainConfigFile+".bak")

    # write out merged yaml config
    with open(mainConfigFile, 'w') as outputFile:
      yaml.dump(config, outputFile)

if __name__ == "__main__":
    mainConfigFile = argv[1]
    patchFiles = argv[2:]
    patchConfig(mainConfigFile, patchFiles)