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Mojo::ACME - Mojo-based ACME-protocol client


  use Mojolicious::Lite;
  plugin 'ACME';
  get '/' => {text => 'Hello World'};

  # then on the command line, while the app is available on port 80
  # NOTE! you should use -t when testing on following command

  # register an account key if necessary
  $ ./ acme account register
  Writing account.key

  # generate your domain cert
  $ ./ acme cert generate
  Writing myapp.key
  Writing myapp.crt

  # install your cert and restart your server per server instructions


Let's Encrypt (also known as letsencrypt) is a service that provices free SSL certificates via an automated system. The service uses (and indeed defines) a protocol called ACME to securely communicate authentication, verification, and certificate issuance. If you aren't familiar with ACME or at least certificate issuance, you might want to see how it works first. While many clients already exist, web framework plugins have the unique ability to handle the challenge response internally and therefore make for the easiest possible letsencrypt (or other ACME service) experience.


The plugin and command level apis should be fairly standardized; the author expects few changes to this level of the system. That said, the lower level modules, like Mojo::ACME are to be considered unstable and should not be relied upon. Use of these classes directly is highly discouraged for the time being.


The system consists of three major component classes, the plugin Mojolicious::Plugin::ACME, the commands, and the lower level classes which they rely on.


The plugin is the glue that holds the system together. It adds the acme command (and its subcommands) to your app's command system. It also establishes a route which handles the challenge request from the ACME service. During your certificate issuance, you must prove that you control the requested domain by serving specified content at a specific location. This route makes that possible.

The plugin itself reads configuration out of the application's config method. This can be set directly in the application or loaded from a file via say Mojolicious::Plugin::Config in the usual way. It looks for a config key acme containing a hash of configuration options. Those options can be seen in the Mojolicious::Plugin::ACME documentation.

The most important of these is challenge_url. In order to know how to respond to the challenge request, your server will make a signed HTTP request to your ACME client which will be listening. This url is used both as the listen value of the ACME client's built-in server, as well as the base of your server's request. It is advised that you use a url which isn't publically available if possible, though the requests are HMAC signed in any event.


The system provides several commands, including those for creating and verifying an account, as well as certificate issuance (and soon, revoking). The commands are made available simply by using the plugin in your application. They are then available in the same manner as built-in commands

  $ ./ acme ...

While some options are sub-command specific, all sub-commands take a few options. Important among those is the --ca option and more conveniently the --test (or -t) flag. Let's Encrypt has severe rate limiting for issuance of certicates on its production hosts. Using the test flag uses the staging server which has greatly relaxed rate limits, though doesn't issue signed certs or create real accounts. It does however use exactly the same process as the production service and issue valid (if not signed) certs. The author highly recommends trying the process on the staging server first.

Modules (Low Level Usage)

As mentioned before, the author hopes to stabilize the low-level interface to be reusable/accessible, however for the time being that is not so and things WILL CHANGE UNEXPECTEDLY!




Joel Berger, <>


  • Mario Domgoergen (mdom)


Copyright (C) 2016 by Joel Berger and "CONTRIBUTORS"

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.