Add Capistrano task to automate maintenance mode

.gitignore

@@ -20,6 +20,7 @@
 /config/database.yml
 /config/secrets.yml
 /config/deploy-secrets.yml
+/config/maintenance.yml
 
 /coverage
 

config/deploy.rb

@@ -1,5 +1,5 @@
 # config valid only for current version of Capistrano
-lock '3.8.1'
+lock '3.8.2'
 
 def deploysecret(key)
   @deploy_secrets_yml ||= YAML.load_file('config/deploy-secrets.yml')[fetch(:stage).to_s]

config/maintenance.yml.example

@@ -0,0 +1,12 @@
+---
+app_root: '.'
+allowed_ips:
+  - 127.0.0.1
+  - x.x.x.x
+
+allowed_paths:
+  - your/custom/route
+
+reason: 'Website down for maintenance'
+response_code: 503
+retry_after: 3600

lib/capistrano/tasks/maintenance.cap

@@ -0,0 +1,15 @@
+namespace :maintenance do
+  desc "Start maintenance mode (edit config/maintenance.yml to provide parameters)"
+  task :start do
+    on roles(:app) do
+      upload! "config/maintenance.yml", "#{current_path}/tmp/maintenance.yml"
+    end
+  end
+
+  desc "Stop maintenance mode"
+  task :stop do
+    on roles(:app) do
+      execute "rm #{current_path}/tmp/maintenance.yml"
+    end
+  end
+end