Skip to main content

ACME client setup based on Certbot for dns-01 challenges via Azure Cloud services

Project description

Introduction

This repository aims to leverage the automatic renewal of SSL certficates within Azure Cloud in a secure manner.

A wrapper library is provided to automatically renew certifactes based on the ACME DNS-01 challenge by using certbot.

The library supports the usage of best practices for securely handling certificates by:

  • using certbot
  • removing the need of a file system for storing certificates
  • Azure Key Vault for central and only storage of secrets and certificates
  • enabling easy and flexible automation

Installing acme-dns-azure

acme-dns-azure is available on PyPi:

python -m pip install acme-dns-azure

For usage exampless please refer to examples

Scope

Based on the provided configuration and trigger, the wrapper library supports following flow.

architecture

  1. Receive certificates, receive EAB & ACME credentials (if configured), receive ACME account information (if already present) from KeyVault. Resolve DNS and setup certbot related configuration.
  2. Certbot: Init renewal process to certificate authority
  3. Certbot: DNS Challenge - create TXT record
  4. Certbot: Renew certificates
  5. Certbot: DNS Challenge - delete TXT record
  6. Upload renewed certificates, create/update ACME account information as secret within KeyVault.

Note: When using DNS delegation step 3. and 5. differ as the TXT record won´t be deleted.

Features

The library handles following use cases:

  • Create new certificates
  • Update domain references in existing certificates
  • Renew existing certificates

Auth is possible by using:

  • Service Principal
  • User Assigned Identity

Integration

The library can be used by:

  • running as script
  • Python package within your app

Within examples you can find example implementations for running the python package:

  • Azure function
  • Container

usage

Contribute

Fork, then clone the repo:

git clone https://github.com/ZEISS/acme-dns-azure

Install Poetry if you not have it already:

curl -sSL https://install.python-poetry.org | python3 -

Configure the virtual environment with full example support and activate it:

Install dependencies

poetry install --all-extras
source .venv/bin/activate

Lint

poetry run black .

Run unit tests

poetry run coverage run
poetry run coverage report

Run integration tests

See How to run integration tests

Release

For releasing a new version, create a PR with one of following labels:

  • minor
  • major
  • patch
  • prepatch
  • preminor
  • premajor
  • prerelease

Usage

Config

The config is written in YAML format, defined by the scheme described below. Brackets indicate that a parameter is optional. For non-list parameters the value is set to the specified default.

Generic placeholders are defined as follows:

  • <boolean>: a boolean that can take the values true or false
  • <int>: a regular integer
  • <string>: a regular string
  • <secret>: a regular string that is a secret, such as a password

The other placeholders are specified separately.

See examples for configuration examples.

# Azure credentials choice section. Only one of the following flags should be set to true to indicate which credentials to use. Otherwise an exception would be raised by the validator. 
# These values are translated into ini file as specified here: https://docs.certbot-dns-azure.co.uk/en/latest/index.html#certbot-azure-workload-identity-ini
# If no flag is provided the program will try to use sp_client_* values to use service principal credentials first. If those are not both present it will try to use managed_identity_id.
[use_system_assigned_identity_credentials: <boolean>]
[use_azure_cli_credentials: <boolean>]
[use_workload_identity_credentials: <boolean>]
[use_managed_identity_credentials: <boolean>]
[use_provided_service_principal_credentials: <boolean>]

# Client ID of managed identity. Must be provided if use_managed_identity_credentials is true. Will be used even if all use_*_credentials flags are set to false, but only if sp_client_* values are not all provided.
[managed_identity_id: <string>]

# sp_client_* values must be provided if use_provided_service_principal_credentials is true. Will be used even if all use_*_credentials flags are set to false. User must specify id and either secret or certificate path. If both values (id and pwd/cert path) are provided and none of the flags is set to true it has precedence over the use of provided managed_identity_id.
[sp_client_id: <string>]
[sp_client_secret: <secret>]
[sp_certificate_path: <string>]
# End of Azure credentials choice section.

[azure_environment: <string> | default = "AzurePublicCloud"]

# Flag if existing certificates containing multiple domains should be renewed and updated based on the definition of the config file. If not set, mismatching certificates will be skipped.
[update_cert_domains: <boolean> | default = False]

# key vault uri for renewal of certifcate
key_vault_id : <string>

# ACME Certificate Authority
server : <string>

# Secret name within key vault for storing ACME Certificate authority account information
[keyvault_account_secret_name: <regex> | default "acme-account-$(network location of server)"]
# when server=https://example.com/something, then keyvault_account_secret_name="acme-account-example-com"

# config file content for certbot client
[certbot.ini : <string> | default = ""]

NOTE: Either managed_identity_id or sp_client_id and sp_client_secret must be specified.

NOTE: certbot.ini represents the CERTBOT configuration file and will be passed into certbot by the acme_dns_azure library as defined. Misconfiguration will lead to failures of certbot and therefore of the renewal process.

Following values will be added to the configurataion file by the acme_dns_azure library per default:

preferred-challenges: dns
authenticator: dns-azure
agree-tos: true

[<eab>]

  # External account binding configuration for ACME, with key ID and base64encoded HMAC key
  [enabled: <boolean> |  default = false]
  [kid_secret_name : <string> | default="acme-eab-kid"]
  [hmac_key_secret_name : <secret> default="acme-eab-hmac-key"]
certificates:
  - <certificate>

<certificate>

# Certbot certficate name. The name will also be used for Azure keyvault certificate name.
name: <string>
# Azure dns zone resource ID used for ACME DNS01 challenge
dns_zone_resource_id: <string>
# renewal in days before expiry for certificate to be renewed. Default is 30
[renew_before_expiry: <int>]
domains:
  - <domain>

<domain>

# domain name this certificate is valid for. Wildcard supported.
name: <string>
# Azure dns zone resource ID used for ACME DNS01 challenge
[dns_zone_resource_id: <string>]

Manual running the library

For running the module as script 'sp_client_id' and 'sp_client_secret' are required. 'managed_identity_id' is not supported.

# from config file
python acme_dns_azure/client.py --config-file-path $CONFIG_File_PATH
# from env
python acme_dns_azure/client.py --config-env-var $ENV_VAR_NAME_CONTAINING_CONFIG

Permission Handling

Best follow security recommendations from Azure.

When working with shared DNS Zones, one can work with DNS delegation with limited permissions:

Example:

Record Name Value Permission
TXT _acme-dedicated - DNS Zone Contributor
CNAME _acme-challenge.mysubdomain _acme-dedicated.fqdn. None

The CNAME and TXT record must be created upfront to enable users to use certbot. The permissions are required on the identity triggering certbot.

With this setup, a DNS Zone owner can limit permissions and enable Users to Create/Renew certificates for their subdomain and ensuring that users cannot aquire certificates for other domains or interfer with existsing records.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

acme_dns_azure-0.4.0.tar.gz (20.0 kB view details)

Uploaded Source

Built Distribution

acme_dns_azure-0.4.0-py3-none-any.whl (20.8 kB view details)

Uploaded Python 3

File details

Details for the file acme_dns_azure-0.4.0.tar.gz.

File metadata

  • Download URL: acme_dns_azure-0.4.0.tar.gz
  • Upload date:
  • Size: 20.0 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? No
  • Uploaded via: poetry/1.8.3 CPython/3.12.1 Linux/6.5.0-1024-azure

File hashes

Hashes for acme_dns_azure-0.4.0.tar.gz
Algorithm Hash digest
SHA256 207a681ca66e91cd4d3ba8a0da4636a5245bc2d3a1affb85f717da22224b83b6
MD5 1db1a0f8fab6e7a15495420504e08ed2
BLAKE2b-256 71263403d57937b37caffefa233756dc50e1dfdcd575d66f500bf27f237884d0

See more details on using hashes here.

File details

Details for the file acme_dns_azure-0.4.0-py3-none-any.whl.

File metadata

  • Download URL: acme_dns_azure-0.4.0-py3-none-any.whl
  • Upload date:
  • Size: 20.8 kB
  • Tags: Python 3
  • Uploaded using Trusted Publishing? No
  • Uploaded via: poetry/1.8.3 CPython/3.12.1 Linux/6.5.0-1024-azure

File hashes

Hashes for acme_dns_azure-0.4.0-py3-none-any.whl
Algorithm Hash digest
SHA256 c1f2d51c1f53a5bb174176a3e4b982e4648942e12bc18f31ba5ae9614028590d
MD5 77189212566cef38dc458c319a199b54
BLAKE2b-256 4cbfa224cb5bfaeb26a90658f6d7a6c288b3c0415ea0274a8b37a9bcfa243a17

See more details on using hashes here.

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page