Add task to move SMTP settings to secrets.yml

Existing installations having their configuration settings in the
capistrano shared folder needed this migration.

Note we can't just use `YAML.load` because we'd lose the anchors defined
in the file. So we have to parse the file the hard way.

config/deploy.rb

@@ -46,6 +46,9 @@ namespace :deploy do
   before "deploy:migrate", "remove_local_census_records_duplicates"
 
   after "deploy:migrate", "add_new_settings"
+
+  before :publishing, "smtp_secrets"
+
   after :publishing, "deploy:restart"
   after :published, "delayed_job:restart"
   after :published, "refresh_sitemap"
@@ -127,3 +130,13 @@ task :setup_puma do
     end
   end
 end
+
+task :smtp_secrets do
+  on roles(:app) do
+    within release_path do
+      with rails_env: fetch(:rails_env) do
+        execute :rake, "secrets:smtp"
+      end
+    end
+  end
+end

lib/tasks/secrets.rake

@@ -0,0 +1,23 @@
+namespace :secrets do
+  desc "Add SMTP settings to secrets.yml"
+  task smtp: :environment do
+    exit if Rails.application.secrets.smtp_settings
+
+    current_settings = {
+      "mailer_delivery_method" => ActionMailer::Base.delivery_method.to_s,
+      "smtp_settings"          => ActionMailer::Base.smtp_settings.stringify_keys
+    }
+
+    secrets = Rails.application.config.paths["config/secrets"].first
+    stream = Psych.parse_stream(File.read(secrets))
+    nodes = stream.children.first.children.first
+
+    environment_index = nodes.children.index do |child|
+      child.is_a?(Psych::Nodes::Scalar) && child.value == Rails.env
+    end
+
+    nodes.children[environment_index + 1].children.push(*Psych.parse(current_settings.to_yaml).children.first.children)
+
+    File.open(secrets, "w") { |file| file.write stream.to_yaml }
+  end
+end