1 files changed, 149 insertions, 0 deletions
diff --git a/lib/chef/resource/alternatives.rb b/lib/chef/resource/alternatives.rb
new file mode 100644
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+++ b/lib/chef/resource/alternatives.rb
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+#
+# Copyright:: 2020, Chef Software Inc.
+# Copyright:: 2016-2020, Virender Khatri
+#
+# 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_relative "../resource"
+
+class Chef
+  class Resource
+    class Alternatives < Chef::Resource
+      unified_mode true
+
+      provides(:alternatives) { true }
+
+      description "The alternatives resource allows for configuration of command alternatives in Linux using the alternatives or update-alternatives packages."
+      introduced "16.0"
+
+      property :link_name, String, name_property: true
+      property :link, String, default: lazy { |n| "/usr/bin/#{n.link_name}" }
+      property :path, String
+      property :priority, [String, Integer], coerce: proc { |n| n.to_i }
+
+      def define_resource_requirements
+        requirements.assert(:install) do |a|
+          a.assertion do
+            !new_resource.priority.nil?
+          end
+
+          a.failure_message("Could not set alternatives for #{new_resource.link_name}, you must provide the :priority property")
+        end
+
+        requirements.assert(:install, :set, :remove) do |a|
+          a.assertion do
+            !new_resource.path.nil?
+          end
+
+          a.failure_message("Could not set alternatives for #{new_resource.link_name}, you must provide the :path property")
+        end
+
+        requirements.assert(:install, :set, :remove) do |a|
+          a.assertion do
+            ::File.exist?(new_resource.path)
+          end
+
+          a.whyrun("Assuming file #{new_resource.path} already exists or was created already")
+          a.failure_message("Could not set alternatives for #{new_resource.link_name}, missing #{new_resource.path}")
+        end
+      end
+
+      action :install do
+        if path_priority != new_resource.priority
+          converge_by("adding alternative #{new_resource.link} #{new_resource.link_name} #{new_resource.path} #{new_resource.priority}") do
+            output = shell_out(alternatives_cmd, "--install", new_resource.link, new_resource.link_name, new_resource.path, new_resource.priority)
+            unless output.exitstatus == 0
+              raise "failed to add alternative #{new_resource.link} #{new_resource.link_name} #{new_resource.path} #{new_resource.priority}"
+            end
+          end
+        end
+      end
+
+      action :set do
+        if current_path != new_resource.path
+          converge_by("setting alternative #{new_resource.link_name} #{new_resource.path}") do
+            output = shell_out(alternatives_cmd, "--set", new_resource.link_name, new_resource.path)
+            unless output.exitstatus == 0
+              raise "failed to set alternative #{new_resource.link_name} #{new_resource.path} \n #{output.stdout.strip}"
+            end
+          end
+        end
+      end
+
+      action :remove do
+        if path_exists?
+          converge_by("removing alternative #{new_resource.link_name} #{new_resource.path}") do
+            shell_out(alternatives_cmd, "--remove", new_resource.link_name, new_resource.path)
+          end
+        end
+      end
+
+      action :auto do
+        converge_by("setting auto alternative #{new_resource.link_name}") do
+          shell_out(alternatives_cmd, "--auto", new_resource.link_name)
+        end
+      end
+
+      action :refresh do
+        converge_by("refreshing alternative #{new_resource.link_name}") do
+          shell_out(alternatives_cmd, "--refresh", new_resource.link_name)
+        end
+      end
+
+      action_class do
+        #
+        # @return [String] The appropriate alternatives command based on the platform
+        #
+        def alternatives_cmd
+          if debian?
+            "update-alternatives"
+          else
+            "alternatives"
+          end
+        end
+
+        #
+        # @return [Integer] The current path priority for the link_name alternative
+        #
+        def path_priority
+          # https://rubular.com/r/IcUlEU0mSNaMm3
+          escaped_path = Regexp.new(Regexp.escape("#{new_resource.path} - priority ") + "(.*)")
+          match = shell_out(alternatives_cmd, "--display", new_resource.link_name).stdout.match(escaped_path)
+
+          match.nil? ? nil : match[1].to_i
+        end
+
+        #
+        # @return [String] The current path for the link_name alternative
+        #
+        def current_path
+          # https://rubular.com/r/ylsuvzUtquRPqc
+          match = shell_out(alternatives_cmd, "--display", new_resource.link_name).stdout.match(/link currently points to (.*)/)
+          match[1]
+        end
+
+        #
+        # @return [Boolean] does the path exist for the link_name alternative
+        #
+        def path_exists?
+          # https://rubular.com/r/ogvDdq8h2IKRff
+          escaped_path = Regexp.new(Regexp.escape("#{new_resource.path} - priority"))
+          shell_out(alternatives_cmd, "--display", new_resource.link_name).stdout.match?(escaped_path)
+        end
+      end
+    end
+  end
+end