sewer 0.5.3

Sewer is a programmatic Lets Encrypt(ACME) client

Sewer

Sewer is a Let’s Encrypt(ACME) client.

It’s name is derived from Kenyan hip hop artiste, Kitu Sewer.

It allows you to obtain ssl/tls certificates from Let’s Encrypt.

Let’s Encrypt is a free, automated, and open Certificate Authority. - https://letsencrypt.org

Sewer currently only supports the DNS mode of validation, I have no plans of supporting other modes of validation.

The currently supported DNS providers are:

1. Cloudflare

2. Aurora

3. acme-dns 4. Bring your own dns provider …

Sewer can be used very easliy programmatically as a library from code.

Sewer also comes with a command-line(cli) interface(app) that you can use from your favourite terminal

Installation

pip3 install sewer

sewer(since version 0.5.0) is now python3 only. To install the (now unsupported) python2 version, run;

pip install sewer==0.3.0

Sewer is in active development and it’s API may change in backward incompatible ways.

https://pypi.python.org/pypi/sewer

Usage

import sewer

dns_class = sewer.CloudFlareDns(CLOUDFLARE_EMAIL='[e-mail]',
                                CLOUDFLARE_API_KEY='nsa-grade-api-key')

# 1. to create a new certificate:
client = sewer.Client(domain_name='example.com',
                      dns_class=dns_class)
certificate = client.cert()
certificate_key = client.certificate_key
account_key = client.account_key

print("your certificate is:", certificate)
print("your certificate's key is:", certificate_key)
print("your letsencrypt.org account key is:", account_key)
# NB: your certificate_key and account_key should be SECRET.
# keep them very safe.

# you can write these out to individual files, eg::

with open('certificate.crt', 'w') as certificate_file:
    certificate_file.write(certificate)
with open('certificate.key', 'w') as certificate_key_file:
    certificate_key_file.write(certificate_key)
with open('account_key.key', 'w') as account_key_file:
    account_key_file.write(account_key)


# 2. to renew a certificate:
import sewer

dns_class = sewer.CloudFlareDns(CLOUDFLARE_EMAIL='[e-mail]',
                                CLOUDFLARE_API_KEY='nsa-grade-api-key')

with open('account_key.key', 'r') as account_key_file:
    account_key = account_key_file.read()

client = sewer.Client(domain_name='example.com',
                      dns_class=dns_class,
                      account_key=account_key)
certificate = client.renew()
certificate_key = client.certificate_key

with open('certificate.crt', 'w') as certificate_file:
    certificate_file.write(certificate)
with open('certificate.key', 'w') as certificate_key_file:
    certificate_key_file.write(certificate_key)

# 3. You can also request/renew wildcard certificates:
import sewer
dns_class = sewer.CloudFlareDns(CLOUDFLARE_EMAIL='[e-mail]',
                                CLOUDFLARE_API_KEY='nsa-grade-api-key')
client = sewer.Client(domain_name='*.example.com',
                      dns_class=dns_class)
certificate = client.cert()
certificate_key = client.certificate_key
account_key = client.account_key

CLI

Sewer also ships with a commandline interface(called sewer or sewer-cli) that you can use to get/renew certificates.

Your dns providers credentials need to be supplied as environment variables.

To get certificate, run:

CLOUDFLARE_EMAIL=[e-mail] \
CLOUDFLARE_API_KEY=api-key \
sewer \
--dns cloudflare \
--domain example.com \
--action run

To renew a certificate, run:

CLOUDFLARE_EMAIL=[e-mail] \
CLOUDFLARE_API_KEY=api-key \
sewer \
--account_key /path/to/your/account.key \
--dns cloudflare \
--domain example.com \
--action renew

To see help:

sewer --help

usage: sewer [-h] [--version] [--account_key ACCOUNT_KEY] --dns
             {cloudflare,aurora,acmedns} --domain DOMAIN
             [--alt_domains [ALT_DOMAINS [ALT_DOMAINS ...]]]
             [--bundle_name BUNDLE_NAME] [--endpoint {production,staging}]
             [--email EMAIL] --action {run,renew}

Sewer is a Let's Encrypt(ACME) client.

optional arguments:
  -h, --help            show this help message and exit
  --version             The currently installed sewer version.
  --account_key ACCOUNT_KEY
                        The path to your letsencrypt/acme account key. eg:
                        --account_key /home/myaccount.key
  --dns {cloudflare,aurora,acmedns}
                        The name of the dns provider that you want to use.
  --domain DOMAIN       The domain/subdomain name for which you want to
                        get/renew certificate for. eg: --domain example.com
  --alt_domains [ALT_DOMAINS [ALT_DOMAINS ...]]
                        A list of alternative domain/subdomain name/s(if any)
                        for which you want to get/renew certificate for. eg:
                        --alt_domains www.example.com blog.example.com
  --bundle_name BUNDLE_NAME
                        The name to use for certificate certificate key and
                        account key. Default is value of domain.
  --endpoint {production,staging}
                        Whether to use letsencrypt/acme production/live
                        endpoints or staging endpoints. production endpoints
                        are used by default. eg: --endpoint staging
  --email EMAIL         Email to be used for registration and recovery. eg:
                        --email [e-mail]
  --action {run,renew}  The action that you want to perform. Either run (get a
                        new certificate) or renew (renew a certificate). eg:
                        --action run
  --loglevel LEVEL      The log level to output log messages at. eg: --loglevel INFO

The cerrtificate, certificate key and account key will be saved in the directory that you run sewer from.

The commandline interface(app) is called sewer or alternatively you could use, sewer-cli.

Features

• Obtain certificates.
• Renew certificates.
• Supports multiple DNS providers.
• Supports wildcard certificates
• Supports acme version 2 only.
• Bring your own dns provider
• Support for SAN certificates.
• Can be used as a python library as well as a command line(CLI) application.
• Bundling certificates.
• Well written(if I have to say so myself):
• Good test coverage
• Passing continous integration
• High grade statically analyzed code

Bring your own DNS provider

Currently, sewer only supports cloudflare and Aurora, out of the box.

However, it is very easy to use another dns provider with sewer.

All you have to do is create your own dns class that is a child class of `sewer.BaseDns <https://github.com/komuw/sewer/blob/master/sewer/dns_providers/common.py>`__ and then implement the

create_dns_record and delete_dns_record methods.

As an example, if you wanted to use AWS route53 as your dns provider with sewer, you

would do something like;

import sewer
import boto3


class AWSroute53Dns(sewer.BaseDns):
    def __init__(self,
                 HostedZoneId,
                 AWS_ACCESS_KEY_ID,
                 AWS_SECRET_ACCESS_KEY):
        self.dns_provider_name = 'AWS_route53'
        self.HostedZoneId = HostedZoneId
        self.boto_client = boto3.client(
            'route53', aws_access_key_id=AWS_ACCESS_KEY_ID,
            aws_secret_access_key=AWS_SECRET_ACCESS_KEY)
        super(AWSroute53Dns, self).__init__()

    def create_dns_record(self,
                          domain_name,
                          domain_dns_value):
        """
        AWS route53 with boto3 documentation;
        https://boto3.readthedocs.io/en/latest/reference/services/route53.html#Route53.Client.change_resource_record_sets
        """
        # do whatever is necessary for your particular DNS provider to create a TXT DNS record
        # eg for AWS route53, it will be something like::
        self.boto_client.change_resource_record_sets(
            HostedZoneId=self.HostedZoneId,
            ChangeBatch={
                'Changes': [
                    {
                        'Action': 'CREATE',
                        'ResourceRecordSet': {
                            'Name': '_acme-challenge' + '.' + domain_name + '.',
                            'Type': 'TXT',
                            'TTL': 123,
                            'ResourceRecords': [
                                {
                                    'Value': "{0}".format(domain_dns_value)},
                            ]}},
                ]})

    def delete_dns_record(self,
                          domain_name,
                          domain_dns_value):
        # do whatever is necessary for your particular DNS provider to delete a TXT DNS record
        # eg for AWS route53, it will be something like::
        self.boto_client.change_resource_record_sets(
            HostedZoneId=self.HostedZoneId,
            ChangeBatch={
                'Changes': [
                    {
                        'Action': 'DELETE',
                        'ResourceRecordSet': {
                            'Name': '_acme-challenge' + '.' + domain_name + '.',
                            'Type': 'TXT',
                            'TTL': 123,
                            'ResourceRecords': [
                                {
                                    'Value': "{0}".format(domain_dns_value)},
                            ]}},
                ]})


custom_route53_dns_class = AWSroute53Dns(
    HostedZoneId='my-zone', AWS_ACCESS_KEY_ID='access-key',
    AWS_SECRET_ACCESS_KEY='secret-access-key')

# create a new certificate:
client = sewer.Client(domain_name='example.com',
                      dns_class=custom_route53_dns_class)
certificate = client.cert()
certificate_key = client.certificate_key
account_key = client.account_key
print("certificate::", certificate)
print("certificate's key::", certificate_key)

Development setup

• fork this repo.

• you need to have python3 installed, this project is python3 only since sewer version 0.5.0.

• cd sewer

• sudo apt-get install pandoc

• open an issue on this repo. In your issue, outline what it is you want to add and why.

• install pre-requiste software:

  apt-get -y install pandoc && pip3 install -e .[dev,test]
  

• make the changes you want on your fork.

• your changes should have backward compatibility in mind unless it is impossible to do so.

• add your name and contact(optional) to CONTRIBUTORS.md

• add tests

• format your code using autopep8:

  autopep8 --experimental --in-place -r -aaaaaaaaaaa .
  

• run flake8 on the code and fix any issues:

  flake8 .
  

• run pylint on the code and fix any issues:

  pylint --enable=E --disable=W,R,C sewer/
  

• run tests and make sure everything is passing:

  make test
  

• open a pull request on this repo.

  NB: I make no commitment of accepting your pull requests.

TODO

• support more DNS providers
• https://github.com/komuW/sewer/milestone/1

FAQ

• Why another ACME client? I wanted an ACME client that I could use to programmatically(as a library) acquire/get certificates. However I could not find anything satisfactory for use in Python code.
• Why is it called Sewer? I really like the Kenyan hip hop artiste going by the name of Kitu Sewer.

Here’s the ouput of running sewer using the cli app:

CLOUDFLARE_EMAIL=[e-mail] \
CLOUDFLARE_API_KEY=nsa-grade-api-key \
sewer \
--endpoint staging \
--dns cloudflare \
--domain subdomain.example.com \
--action run

2018-03-06 18:08.41 chosen_dns_provider            message=Using cloudflare as dns provider.

2018-03-06 18:08.46 acme_register                  acme_server=https://acme-staging... domain_names=['subdomain.example.com'] sewer_version=0.5.0b
2018-03-06 18:08.52 acme_register_response         acme_server=https://acme-staging... domain_names=['subdomain.example.com']

2018-03-06 18:08.52 apply_for_cert_issuance        acme_server=https://acme-staging... domain_names=['subdomain.example.com'] sewer_version=0.5.0b
2018-03-06 18:09.01 apply_for_cert_issuance_response acme_server=https://acme-staging... domain_names=['subdomain.example.com']

2018-03-06 18:09.08 create_dns_record              dns_provider_name=CloudFlareDns
2018-03-06 18:09.16 create_cloudflare_dns_record_response dns_provider_name=CloudFlareDns status_code=200

2018-03-06 18:09.36 send_csr                       acme_server=https://acme-staging... domain_names=['subdomain.example.com'] sewer_version=0.5.0b
2018-03-06 18:09.45 send_csr_response              acme_server=https://acme-staging... domain_names=['subdomain.example.com']

2018-03-06 18:09.45 download_certificate           acme_server=https://acme-staging... domain_names=['subdomain.example.com'] sewer_version=0.5.0b
2018-03-06 18:09.50 download_certificate_response  acme_server=https://acme-staging... domain_names=['subdomain.example.com']

2018-03-06 18:09.54 the_end                        message=Certificate Succesfully issued. The certificate, certificate key and account key have been saved in the current directory