import os
from glob import glob
import yaml

with open("etc/backup.d/backup.yml") as f:
    config = yaml.load(f)

sources = {}
for source in config['sources']:
    for path in glob('etc/backup.d/{}/*.yml'.format(source)):
        with open(path) as f:
            if source not in sources:
                sources[source] = {}
            sources[source][os.path.basename(path)] = yaml.load(f)

config['sources'] = sources
print(config)