feat(facts): add fact about certbot version

README.md

@@ -255,6 +255,15 @@ letsencrypt::renew_deploy_hook_commands:
 
 ## Facts
 
+* [certbot_version](#fact-certbotversion)
+* [letsencrypt_directory](#fact-letsencryptdirectory)
+
+### Fact: certbot_version
+
+A Facter fact that can be used to determine what the default version of certbot is for your operating system/distribution.
+
+### Fact: letsencrypt_directory
+
 Facts about your live certificates are available through facter. You can query the list of live certificates from puppet using `$::letsencrypt_directory` in your puppet code, hiera data or from the command line.
 
 ```

lib/facter/certbot_version.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+Facter.add(:certbot_version) do
+  confine kernel: %w[FreeBSD Linux OpenBSD]
+
+  setcode do
+    value = nil
+    certbot = Facter::Util::Resolution.which('certbot')
+    if certbot
+      output = Facter::Util::Resolution.exec("#{certbot} --version 2>/dev/null")
+      unless output.nil?
+        value = output[%r{^certbot (.*)$}, 1]
+      end
+    end
+    value
+  end
+end