Bullion is an ACMEv2-compatible Certificate Authority (just like Let's Encrypt). Bullion makes it easy to leverage open standards for provisioning certificates for internal sites and services. Things like cert-manager, certbot, and many other technologies work great with Let's Encrypt for external hostnames, but for private domains and servers that aren't Internet accessible, there are few easy options.

Bullion installs easily (both as a ruby gem or a Docker image) and will shortly come with Kubernetes examples and even a helm chart to make installing it that much easier. For its data, Bullion works with either SQLite3 for very small sites (where HA and high-throughput isn't a concern) or with MariaDB/MySQL.

The goal of the Bullion project is to make running a scalable, internal ACMEv2 CA easy. Either make a custom root CA certificate or give Bullion a signed intermediary to use in simple, compatible PEM format and you're up and running.

• Let's Encrypt? Let's Encrypt is a fantastic service and has help make securing communication over the Internet easy and free. That said, for internal (e.g., inside the firewall) communication, it isn't particularly useful.

• Boulder? Let's Encrypt's Boulder is the code used by Let's Encrypt to run their public service. It is, of course, fantastic software. That said, it is a pretty complex architecture consisting of many components. It is built to scale to the needs of a huge number of public users. Per the Boulder documentation, "often Boulder is not the right fit for organizations that are evaluating it for production usage". It may meet your needs, but it is probably both overkill and more difficult to get up and running than you'll need.

• cfssl? The "cfssl" project is a great tool for running a tiny CA for manually managing certs. It is certainly easier than using OpenSSL directly. While it offers an API, it isn't an ACME-compliant API and has less integration with things like Kubernetes. While I'm a fan of the project but it didn't meet my needs with creating certificates through automation and at the scale I need.

• step-ca? The step-ca project is a well-documented and robust CA and includes nearly all the features of Bullion. It really is wonderful, but the project takes on more than the goal of managing the provisioning of certificates via the ACME protocol. While there's no strong argument against using step-ca, it might be more complicated to setup and manage than Bullion for your scenario.

TODO: Write instructions for starting Bullion

Whether run locally or via Docker, the following environment variables configure Bullion:

Any client that speaks the ACMEv2 protocol can be pointed at /acme/directory and everything else can be auto-discovered.

Bullion also supports a non-standard directory option caBundle (which directs clients to /acme/cabundle) that responds with Bullion's PEM-encoded public key. Trusting this should automatically trust certificates signed by Bullion (eliminating browser messages about untrusted/unverified certificates).

Bullion provides a /ping endpoint that should respond with { 'status': 'up' } when Bullion is functional and ready to receive requests.

Prometheus metrics are also scrapable at /metrics. This includes typical web request information as well as latencies related to the different Challenge types.

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.

Bug reports and pull requests are welcome on GitHub at https://github.com/jgnagy/bullion. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

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

Everyone interacting in the Bullion project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.