Document the ingress controllers

1 files changed, 41 insertions, 0 deletions

diff --git a/app/controllers/action_mailbox/ingresses/postfix/inbound_emails_controller.rb b/app/controllers/action_mailbox/ingresses/postfix/inbound_emails_controller.rb
index 133accf651..ba04effd1f 100644
--- a/app/controllers/action_mailbox/ingresses/postfix/inbound_emails_controller.rb
+++ b/app/controllers/action_mailbox/ingresses/postfix/inbound_emails_controller.rb
@@ -1,3 +1,44 @@
+# Ingests inbound emails relayed from Postfix.
+#
+# 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 Postfix ingress can learn its password. You should only use the Postfix 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 could not be authenticated
+# - <tt>404 Not Found</tt> if Action Mailbox is not configured to accept inbound emails from Postfix
+# - <tt>415 Unsupported Media Type</tt> if the request does not contain an RFC 822 message
+# - <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 Postfix:
+#
+#        # config/environments/production.rb
+#        config.action_mailbox.ingress = :postfix
+#
+# 2. Generate a strong password that Action Mailbox can use to authenticate requests to the Postfix 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 Postfix}{https://serverfault.com/questions/258469/how-to-configure-postfix-to-pipe-all-incoming-email-to-a-script}
+#    to pipe inbound emails to <tt>bin/rails action_mailbox:ingress:postfix</tt>, providing the +URL+ of the Postfix
+#    ingress and the +INGRESS_PASSWORD+ you previously generated.
+#
+#    If your application lived at <tt>https://example.com</tt>, the full command would look like this:
+#
+#        URL=https://example.com/rails/action_mailbox/postfix/inbound_emails INGRESS_PASSWORD=... bin/rails action_mailbox:ingress:postfix
 class ActionMailbox::Ingresses::Postfix::InboundEmailsController < ActionMailbox::BaseController
   before_action :authenticate_by_password, :require_valid_rfc822_message