Merge pull request #34907 from wildbit/actionmailbox-postmark

Add Postmark ingress support to ActionMailbox

1 files changed, 62 insertions, 0 deletions

diff --git a/actionmailbox/app/controllers/action_mailbox/ingresses/postmark/inbound_emails_controller.rb b/actionmailbox/app/controllers/action_mailbox/ingresses/postmark/inbound_emails_controller.rb
new file mode 100644
index 0000000000..ec4e0da5ec
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+++ b/actionmailbox/app/controllers/action_mailbox/ingresses/postmark/inbound_emails_controller.rb
@@ -0,0 +1,62 @@
+# frozen_string_literal: true
+
+module ActionMailbox
+  # Ingests inbound emails from Postmark. Requires +RawEmail+ parameter containing a full RFC 822 message.
+  #
+  # Authenticates requests using HTTP basic access authentication. The username is always +actionmailbox+, and the
+  # password is read from the application's encrypted credentials or an environment variable. See the Usage section below.
+  #
+  # Note that basic authentication is insecure over unencrypted HTTP. An attacker that intercepts cleartext requests to
+  # the Postmark ingress can learn its password. You should only use the Postmark ingress over HTTPS.
+  #
+  # Returns:
+  #
+  # - <tt>204 No Content</tt> if an inbound email is successfully recorded and enqueued for routing to the appropriate mailbox
+  # - <tt>401 Unauthorized</tt> if the request's signature could not be validated
+  # - <tt>404 Not Found</tt> if Action Mailbox is not configured to accept inbound emails from Postmark
+  # - <tt>422 Unprocessable Entity</tt> if the request is missing the required +RawEmail+ parameter
+  # - <tt>500 Server Error</tt> if the ingress password is not configured, or if one of the Active Record database,
+  #   the Active Storage service, or the Active Job backend is misconfigured or unavailable
+  #
+  # == Usage
+  #
+  # 1. Tell Action Mailbox to accept emails from Postmark:
+  #
+  #        # config/environments/production.rb
+  #        config.action_mailbox.ingress = :postmark
+  #
+  # 2. Generate a strong password that Action Mailbox can use to authenticate requests to the Postmark ingress.
+  #
+  #    Use <tt>rails credentials:edit</tt> to add the password to your application's encrypted credentials under
+  #    +action_mailbox.ingress_password+, where Action Mailbox will automatically find it:
+  #
+  #        action_mailbox:
+  #          ingress_password: ...
+  #
+  #    Alternatively, provide the password in the +RAILS_INBOUND_EMAIL_PASSWORD+ environment variable.
+  #
+  # 3. {Configure Postmark inbound webhook}[https://postmarkapp.com/manual#configure-your-inbound-webhook-url]
+  #    to forward inbound emails to +/rails/action_mailbox/postmark/inbound_emails+ with the username +actionmailbox+ and
+  #    the password you previously generated. If your application lived at <tt>https://example.com</tt>, you would
+  #    configure Postmark with the following fully-qualified URL:
+  #
+  #        https://actionmailbox:PASSWORD@example.com/rails/action_mailbox/postmark/inbound_emails
+  #
+  #    *NOTE:* When configuring your Postmark inbound webhook, be sure to check the box labeled *"Include raw email
+  #    content in JSON payload"*. Action Mailbox needs the raw email content to work.
+  class Ingresses::Postmark::InboundEmailsController < ActionMailbox::BaseController
+    before_action :authenticate_by_password
+
+    def create
+      ActionMailbox::InboundEmail.create_and_extract_message_id! params.require("RawEmail")
+    rescue ActionController::ParameterMissing => error
+      logger.error <<~MESSAGE
+        #{error.message}
+
+        When configuring your Postmark inbound webhook, be sure to check the box
+        labeled "Include raw email content in JSON payload".
+      MESSAGE
+      head :unprocessable_entity
+    end
+  end
+end