Generate and output Let's Encrypt certificate for Zappa project

zappa_cert.py

import os, sys
from zappa.cli import ZappaCLI
from zappa.util import parse_s3_url
from zappa import letsencrypt

# get command line arguments
directory, stage, output_filename = sys.argv[1:]

# change working directory
owd = os.getcwd()
os.chdir(directory)

# initialize zappa instance
cli = ZappaCLI()
cli.api_stage = stage
zappa_instance = cli.load_settings()
zappa_instance.lambda_name = cli.lambda_name

# get settings
domain = cli.stage_config.get('domain')
account_key_location = cli.stage_config.get('lets_encrypt_key')
assert domain
assert account_key_location

# prepare let's encrypt key
if account_key_location.startswith('s3://'):
    bucket, key_name = parse_s3_url(account_key_location)
    zappa_instance.s3_client.download_file(bucket, key_name, '/tmp/account.key')
else:
    from shutil import copyfile
    copyfile(account_key_location, '/tmp/account.key')

print 'Getting certificate for ' + domain + '..'

# get the certificate
letsencrypt.create_domain_key()
letsencrypt.create_domain_csr(domain)
letsencrypt.get_cert(zappa_instance)
letsencrypt.create_chained_certificate()

with open('/tmp/signed.crt') as f:
    certificate_body = f.read()

with open('/tmp/domain.key') as f:
    certificate_private_key = f.read()

with open('/tmp/intermediate.pem') as f:
    certificate_chain = f.read()

letsencrypt.cleanup()

# output the certificate
os.chdir(owd)
with open(output_filename, 'w') as f:
    f.write('# Certificate body\n\n')
    f.write(certificate_body + '\n')
    f.write('# Certificate private key\n\n')
    f.write(certificate_private_key + '\n')
    f.write('# Certificate chain\n\n')
    f.write(certificate_chain + '\n')

print 'Certificate generated!'