Added an env variable that allows maitenance mode (#679)

app/controllers/application_controller.rb

@@ -36,6 +36,9 @@ class ApplicationController < ActionController::Base
   # Manually handle BigBlueButton errors
   rescue_from BigBlueButton::BigBlueButtonException, with: :handle_bigbluebutton_error
 
+  # Manually Handle errors when application is in readonly mode
+  rescue_from ActiveRecord::ReadOnlyRecord, with: :handle_readonly_error
+
   protect_from_forgery with: :exception
 
   MEETING_NAME_LIMIT = 90
@@ -47,7 +50,7 @@ class ApplicationController < ActionController::Base
   end
 
   def maintenance_mode?
-    if ENV["MAINTENANCE_MODE"].present?
+    if ENV["MAINTENANCE_MODE"] == "full"
       render "errors/greenlight_error", status: 503, formats: :html,
         locals: {
           status_code: 503,
@@ -190,4 +193,10 @@ class ApplicationController < ActionController::Base
   def handle_bigbluebutton_error
     render "errors/bigbluebutton_error"
   end
+
+  # Manually Handle errors when application is in readonly mode
+  def handle_readonly_error
+    flash.clear
+    redirect_to request.referrer, flash: { alert: I18n.t("errors.maintenance.readonly") }
+  end
 end

app/models/application_record.rb

@@ -22,4 +22,8 @@ class ApplicationRecord < ActiveRecord::Base
   def to_param
     uid
   end
+
+  def readonly?
+    ENV["MAINTENANCE_MODE"] == "readonly"
+  end
 end

config/locales/en.yml

@@ -124,6 +124,7 @@ en:
     maintenance:
       message: Sorry, we're down for maintenance.
       help: We'll be back soon!
+      readonly: This application is under maintenance. You will not be able to perform this action
     migration_error:
       contact_admin: If you are not an administrator, please contact one.
       continue: I'd like to stay using 1.0.

sample.env

@@ -144,6 +144,14 @@ NUMBER_OF_ROWS=25
 #   ENABLE_GOOGLE_CALENDAR_BUTTON=true|false
 ENABLE_GOOGLE_CALENDAR_BUTTON=
 
+# Set the application into Maintenance Mode
+#
+# Current options supported:
+# full: Renders an error page that does not allow users to access any of the features in the application
+# readonly: Sets the database to readonly mode, which allows users to use actions that dont write to the database
+# false: Application runs normally
+MAINTENANCE_MODE=false
+
 # Comment this out to send logs to STDOUT in production instead of log/production.log .
 #
 # RAILS_LOG_TO_STDOUT=true