create-gce-user-data

#!/usr/bin/env python
"""
Create CoreOS user-data by merging contric/coreos/user-data and gce-user-data

Usage: create-gce-user-data.py <discovery_url>

Arguments:
  <discovery_url>
    This is the CoreOS etcd discovery URL. You should generate a new URL at
    https://discovery.etcd.io/new and pass it as the argument.
"""

import sys
import os
import re
import yaml
import collections

# TODO: Learn how to use docopt and import it for argument handling and validtion

def combine_dicts(orig_dict, new_dict):
    for key, val in new_dict.iteritems():
        if isinstance(val, collections.Mapping):
            tmp = combine_dicts(orig_dict.get(key, { }), val)
            orig_dict[key] = tmp
        elif isinstance(val, list):
            orig_dict[key] = (orig_dict[key] + val)
        else:
            orig_dict[key] = new_dict[key]
    return orig_dict

try:
  url = sys.argv[1]
except (NameError, IndexError):
  exit('It doesn\'t appear that you specified a discovery URL as the first parameter.')


url_pattern = 'https\:[\/]{2}discovery\.etcd\.io\/[0-9a-f]{32}'

m = re.match(url_pattern, url)

if url and m:
  current_dir = os.path.dirname(__file__)
  gce_user_data = file(os.path.abspath(os.path.join(current_dir, 'gce-user-data')), 'w')
  gce_template = file(os.path.join(current_dir, "gce-user-data-template"), 'r')
  coreos_template = file(os.path.join(current_dir, "../coreos/user-data"), 'r')

  configuration_coreos_template = yaml.safe_load(coreos_template)
  configuration_gce_template = yaml.safe_load(gce_template)

  configuration = combine_dicts(configuration_coreos_template, configuration_gce_template)
  
  configuration['coreos']['etcd']['discovery_url'] = url

  with gce_user_data as outfile:
    try:
      outfile.write("#cloud-config\n\n" + yaml.safe_dump(configuration, default_flow_style=False,  default_style='|'))
    except (IOError, ValueError):
      exit('There was an issue writing to file ' + gce_user_data.name)
    else:
      exit('Wrote file ' + gce_user_data.name + ' with discovery URL ' + url)
else:
  print 'Discovery URL doesn\'t appear to be valid.'