improvements to the auto upgrade script

* change how the channel is passed
* restart rather than stop/start when upgrading
* add safe mode for forcing a stop/start on upgrade

script/auto_upgrade.rb

@@ -1,19 +1,38 @@
 #!/usr/bin/env ruby
 
 # This script will attempt to upgrade a Postal installation automatically.
-# It is always recommended to upgrade Postal manaually and this script should only
-# be used for development or for pro-users.
 #
 # It can be run as any user that has access to /opt/postal and that can run
 # commands as postal.
 
-CHANNEL = ARGV[0] || "stable"
+channel = 'stable'
+safe_mode = false
 
-unless ['beta', 'stable'].include?(CHANNEL)
+begin
+  require 'optparse'
+  OptionParser.new do |opts|
+    opts.banner = "Usage: postal auto-upgrade [options]"
+
+    opts.on("-c", "--channel CHANNEL", "The channel to pull the latest version from") do |v|
+      channel = v
+    end
+
+    opts.on("--safe", "Stop postal before running the upgrade") do |v|
+      safe_mode = true
+    end
+  end.parse!
+rescue OptionParser::InvalidOption => e
+  puts e.message
+  exit 1
+end
+
+unless ['beta', 'stable'].include?(channel)
   puts "Channel must be either 'stable' or 'beta'"
   exit 1
 end
 
+puts "Upgrading from the \e[32m#{channel}\e[0m channel"
+
 def run(command, options = {})
   if system(command)
     # Good.
@@ -23,8 +42,10 @@ def run(command, options = {})
   end
 end
 
-puts "Stopping current Postal instance"
-run "postal stop", :exit_on_failure => false
+if safe_mode
+  puts "Stopping current Postal instance"
+  run "postal stop", :exit_on_failure => false
+end
 
 if File.exist?("/opt/postal/app/.git")
   puts "Getting latest version of repository"
@@ -34,7 +55,7 @@ else
   run "rm -Rf /opt/postal/app.backup"
   run "cp -R /opt/postal/app /opt/postal/app.backup"
   puts "Downloading latest version of application"
-  run "wget https://postal.atech.media/packages/#{CHANNEL}/latest.tgz -O - | tar zxpv -C /opt/postal/app"
+  run "wget https://postal.atech.media/packages/#{channel}/latest.tgz -O - | tar zxpv -C /opt/postal/app"
 end
 
 puts "Installing dependencies"
@@ -43,7 +64,12 @@ run "postal bundle /opt/postal/vendor/bundle"
 puts "Upgrading database & assets"
 run "postal upgrade"
 
-puts "Starting Postal"
-run "postal start"
+if safe_mode
+  puts "Starting Postal"
+  run "postal start"
+else
+  puts "Restarting Postal"
+  run "postal restart"
+end
 
 puts "\e[32mUpgrade complete\e[0m"