Move OS detection to task helpers and add detection of OS X

lib/tasks/gitlab/info.rake

@@ -3,20 +3,6 @@ namespace :gitlab do
     desc "GITLAB | Show information about GitLab and its environment"
     task info: :environment  do
-      # check which OS is running
-      os_name = run("lsb_release -irs")
-      os_name ||= if File.readable?('/etc/system-release')
-                    File.read('/etc/system-release')
-                  end
-      os_name ||= if File.readable?('/etc/debian_version')
-                    debian_version = File.read('/etc/debian_version')
-                    "Debian #{debian_version}"
-                  end
-      os_name ||= if File.readable?('/etc/SuSE-release')
-                    File.read('/etc/SuSE-release')
-                  end
-      os_name.try(:squish!)
-
       # check if there is an RVM environment
       rvm_version = run_and_match("rvm --version", /[\d\.]+/).try(:to_s)
       # check Ruby version

lib/tasks/gitlab/task_helpers.rake

 namespace :gitlab do
+  # Check which OS is running
+  #
+  # It will primarily use lsb_relase to determine the OS.
+  # It has fallbacks to Debian, SuSE and OS X.
+  def os_name
+    os_name = run("lsb_release -irs")
+    os_name ||= if File.readable?('/etc/system-release')
+                  File.read('/etc/system-release')
+                end
+    os_name ||= if File.readable?('/etc/debian_version')
+                  debian_version = File.read('/etc/debian_version')
+                  "Debian #{debian_version}"
+                end
+    os_name ||= if File.readable?('/etc/SuSE-release')
+                  File.read('/etc/SuSE-release')
+                end
+    os_name ||= if os_x_version = run("sw_vers -productVersion")
+                  "Mac OS X #{os_x_version}"
+                end
+    os_name.try(:squish!)
+  end
+
   # Runs the given command and matches the output agains the given pattern
   #
   # Returns nil if nothing matched