merge-yaml-files

import os.path
import sys
import yaml
import json
import importlib
import getopt

from troposphere import Template

sys.path.append(os.path.dirname(os.path.realpath(__file__ + "/..")))

def config_stack(stack_name):
  return {
    'stack': stack_name
  }

def merge(a, b, path=None, update=True):
  "http://stackoverflow.com/questions/7204805/python-dictionaries-of-dictionaries-merge"
  "merges b into a"
  if path is None: path = []
  for key in b:
    if key in a:
      if isinstance(a[key], dict) and isinstance(b[key], dict):
        merge(a[key], b[key], path + [str(key)])
      elif a[key] == b[key]:
        pass # same leaf value
      elif isinstance(a[key], list) and isinstance(b[key], list):
        for idx, val in enumerate(b[key]):
          a[key][idx] = merge(a[key][idx], b[key][idx], path + [str(key), str(idx)], update=update)
      elif update:
        a[key] = b[key]
      else:
        raise Exception('Conflict at %s' % '.'.join(path + [str(key)]))
    else:
      a[key] = b[key]
  return a

def read_yaml_file(filename):
  with open(filename, 'r') as f:
    return yaml.load(f)

def config(stack_name):
  stack = read_yaml_file("stacks/%s.yaml" % stack_name)

  stack_config = merge(config_stack(stack_name), stack)

  config_files = [
    "configuration/templates/%s/config.yaml" % stack['template_name'],
    "configuration/regions/%s/config.yaml" % stack['region'],
    "configuration/stacks/%s/config.yaml" % stack_name,
    "configuration/stacks/%s/secrets.yaml" % stack_name
  ]

  for config_file in config_files:
    if os.path.exists(config_file):
      stack_config = merge(stack_config, read_yaml_file(config_file))

  return stack_config