An effective ACME v2 client: Manage keys on the cloud (e.g. S3)
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sorah Merge pull request #32 from chiro/fix-sample
Fix the directory URLs in the sample configuration in README.
Latest commit 533ceb1 Jun 7, 2018

Acmesmith: A simple, effective ACME v2 client to use with many servers and a cloud

Acmesmith is an ACME (Automatic Certificate Management Environment) client that works perfect on environment with multiple servers. This client saves certificate and keys on cloud services (e.g. AWS S3) securely, then allow to deploy issued certificates onto your servers smoothly. This works well on Let's encrypt.

This tool is written in Ruby, but Acmesmith saves certificates in simple scheme, so you can fetch certificate by your own simple scripts.


  • ACME v2 client designed to work on multiple servers
  • ACME registration, domain authorization, certificate requests
  • Storing keys in several ways
  • Challenge response
  • Many cloud services support
    • AWS S3 storage and Route 53 dns-01 responder support out-of-the-box
    • 3rd party plugins available for OpenStack designate, Google Cloud DNS, simple http-01, and Google Cloud Storage. See Plugins below


Add this line to your application's Gemfile:

gem 'acmesmith'

And then execute:

$ bundle

Or install it yourself as:

$ gem install acmesmith


$ acmesmith new-account CONTACT              # Create account key (contact e.g.
$ acmesmith order COMMON_NAME [SAN]     # request certificate for CN +COMMON_NAME+ with SANs +SAN+
$ acmesmith add-san COMMON_NAME [SAN]     # re-request existing certificate of CN with additional SAN(s)
$ acmesmith list [COMMON_NAME]                          # list certificates or its versions
$ acmesmith current COMMON_NAME                         # show current version for certificate
$ acmesmith show-certificate COMMON_NAME                # show certificate
$ acmesmith show-private-key COMMON_NAME                # show private key
$ acmesmith save-certificate COMMON_NAME --output=PATH  # Save certificate to a file
$ acmesmith save-private-key COMMON_NAME --output=PATH  # Save private key to a file
$ acmesmith save-pkcs12      COMMON_NAME --output=PATH  # Save certificate and private key to a PKCS12 file
$ acmesmith autorenew [-d DAYS] # Renew certificates which being expired soon
# Save (or update) certificate files and key in a one command
$ acmesmith save COMMON_NAME \
      --version-file=/tmp/cert.txt   # Path to save a certificate version for following run 
      --key-file=/tmp/cert.key       # Path to save a key
      --fullchain-file=/tmp/cert.pem # Path to save a certficiate and its chain (concatenated)

See acmesmith help [subcommand] for more help.


See config.sample.yml to start. Default configuration file is ./acmesmith.yml.

# directory: # production

  # configure where to store keys and certificates; described later
  # configure how to respond ACME challenges; described later

account_key_passphrase: password
certificate_key_passphrase: secret



  type: s3
  # prefix:
  # aws_access_key: # aws credentials (optional); If omit, default configuration of aws-sdk use will be used.
  #   access_key_id:
  #   secret_access_key:
  #   session_token:
  # use_kms: true
  # kms_key_id: # KMS key id (optional); if omit, default AWS managed key for S3 will be used
  # kms_key_id_account: # KMS key id for account key (optional); This overrides kms_key_id
  # kms_key_id_certificate_key: # KMS key id for private keys for certificates (optional); This oveerides kms_key_id

This saves certificates and keys in the following S3 keys:

  • {prefix}/account.pem: Account private key in pem
  • {prefix}/certs/{common_name}/current: text file contains current version name
  • {prefix}/certs/{common_name}/{version}/cert.pem: certificate in pem
  • {prefix}/certs/{common_name}/{version}/key.pem: private key in pem
  • {prefix}/certs/{common_name}/{version}/chain.pem: CA chain in pem
  • {prefix}/certs/{common_name}/{version}/fullchain.pem: certificate + CA chain in pem. This is suitable for some server softwares like nginx.


This is not recommended. If you're planning to use this, make sure backing up the keys.

  type: filesystem
  path: /path/to/directory/to/store/keys

Challenge Responders

Challenge responders responds to ACME challenges to prove domain ownership to CA.


Route53 responder supports dns-01 challenge type. This assumes domain NS are managed under Route53 hosted zone.

  - route53:
      # aws_access_key: # aws credentials (optional); If omit, default configuration of aws-sdk use will be used.
      #   access_key_id:
      #   secret_access_key:
      #   session_token:
      # hosted_zone_map: # hosted zone map (optional); This is to specify exactly one hosted zone to use. This will be required when there are multiple hosted zone with same domain name. Usually
      #   "": "/hostedzone/DEADBEEF"

Post Issuing Hooks

Post issuing hooks are configurable actions that are executed when a new certificate has been succesfully issued. The hooks are sequentially executed in the same order as they are configured, and they are configurable per certificate's common-name.


Execute specified command on a shell. Environment variable ${COMMON_NAME} is available.

    - shell:
        command: mail -s "New cert for ${COMMON_NAME} has been issued" < /dev/null
    - shell:
        command: touch /tmp/certs-has-been-issued-${COMMON_NAME}
    - shell:
        command: /usr/bin/dosomethingelse ${COMMON_NAME}


Import certificate into AWS ACM.

    - acm:
        region: us-east-1 # required
        certificate_arn: arn:aws:acm:... # (optional)

When certificate_arn is not present, acm hook attempts to find the certificate ARN from existing certificate list. Certificate with same common name ("domain name" on ACM), and Acmesmith tag will be used. Otherwise, acm hook imports as a new certificate with Acmesmith tag.

3rd party Plugins

Challenge responders


Vendor dependent notes


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


  • Tests
  • Support post actions (notifying servers, deploying to somewhere, etc...)


Bug reports and pull requests are welcome on GitHub at[USERNAME]/acmesmith.


The gem is available as open source under the terms of the MIT License.