Add shard plugin

lib/ohai/plugins/shard.rb

@@ -0,0 +1,52 @@
+#
+# Author:: Phil Dibowitz <[email protected]>
+# Copyright:: Copyright (c) 2016 Facebook, Inc.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+require 'digest/md5'
+
+Ohai.plugin(:ShardSeed) do
+  depends "hostname", "dmi", "machine_id"
+  provides "shard_seed"
+
+  def get_dmi_thing(dmi, thing)
+    %w{system base_board chassis}.each do |section|
+      unless dmi[:thing][thing].compact.empty?
+        return dmi[:thing][thing]
+      end
+    end
+  end
+
+  collect_data(:default) do
+    sources = Ohai.config[:plugin][:shard_seed][:source] || [:fqdn]
+    data = ''
+    sources.each do |src|
+      data << case base
+              when :fqdn
+                fqdn
+              when :hostname
+                hostname
+              when :serial
+                get_dmi_thing(dmi, :serial_number)
+              when :uuid
+                get_dmi_thing(dmi, :uuid)
+              when :machine_id
+                machine_id
+              end
+    end
+    shard_seed Digest::MD5.hexdigest(data)[0...7].to_i(16)
+  end
+end