Add alternatives resource for Linux

This comes from https://github.com/vkhatri/chef-alternatives

Signed-off-by: Tim Smith <tsmith@chef.io>

5 files changed, 234 insertions, 1 deletions

diff --git a/kitchen-tests/cookbooks/end_to_end/recipes/alternatives.rb b/kitchen-tests/cookbooks/end_to_end/recipes/alternatives.rb
new file mode 100644
index 0000000000..8e0a0bb178
--- /dev/null
+++ b/kitchen-tests/cookbooks/end_to_end/recipes/alternatives.rb
@@ -0,0 +1,51 @@
+#
+# Cookbook:: end_to_end
+# Recipe:: alternatives
+#
+
+file "/usr/local/sample-binary-1" do
+  content '#!/bin/bash
+  echo sample-binary-v1
+  '
+  mode "500"
+end
+
+file "/usr/local/sample-binary-2" do
+  content '#!/bin/bash
+  echo sample-binary-v2
+  '
+  mode "550"
+end
+
+alternatives "sample-binary v1" do
+  link_name "sample-binary"
+  path "/usr/local/sample-binary-1"
+  priority 100
+  action :install
+end
+
+alternatives "sample-binary v2" do
+  link_name "sample-binary"
+  path "/usr/local/sample-binary-2"
+  priority 101
+  action :install
+end
+
+alternatives "set sample-binary v1" do
+  link_name "sample-binary"
+  path "/usr/local/sample-binary-1"
+  action :set
+end
+
+alternatives "sample-binary-test v1" do
+  link_name "sample-binary-test"
+  path "/usr/local/sample-binary-1"
+  priority 100
+  action :install
+end
+
+alternatives "sample-binary-test v1" do
+  link_name "sample-binary-test"
+  path "/usr/local/sample-binary-1"
+  action :remove
+end
diff --git a/kitchen-tests/cookbooks/end_to_end/recipes/default.rb b/kitchen-tests/cookbooks/end_to_end/recipes/default.rb
index dc8b44cbf4..eeccb9ffd7 100644
--- a/kitchen-tests/cookbooks/end_to_end/recipes/default.rb
+++ b/kitchen-tests/cookbooks/end_to_end/recipes/default.rb
@@ -118,5 +118,5 @@ end
 end
 
 include_recipe "::chef-vault" unless includes_recipe?("end_to_end::chef-vault")
-
+include_recipe "::alternatives"
 include_recipe "::tests"
diff --git a/lib/chef/resource/alternatives.rb b/lib/chef/resource/alternatives.rb
new file mode 100644
index 0000000000..75916f7269
--- /dev/null
+++ b/lib/chef/resource/alternatives.rb
@@ -0,0 +1,131 @@
+#
+# 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, :set, :remove) do |a|
+          a.assertion do
+            !new_resource.path.nil?
+          end
+
+          a.failure_message("Could not set alternatives for #{new_resource.link_name}, must provide :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
+        raise "missing :priority" unless new_resource.priority
+
+        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
+        def alternatives_cmd
+          if platform_family?("rhel", "amazon", "fedora")
+            "alternatives"
+          else
+            "update-alternatives"
+          end
+        end
+
+        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
+
+        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.nil? ? nil : match[1]
+        end
+
+        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
diff --git a/lib/chef/resources.rb b/lib/chef/resources.rb
index 7d9a24c830..f0736e2429 100644
--- a/lib/chef/resources.rb
+++ b/lib/chef/resources.rb
@@ -16,6 +16,7 @@
 # limitations under the License.
 #
 
+require_relative "resource/alternatives"
 require_relative "resource/apt_package"
 require_relative "resource/apt_preference"
 require_relative "resource/apt_repository"
diff --git a/spec/unit/resource/alternatives_spec.rb b/spec/unit/resource/alternatives_spec.rb
new file mode 100644
index 0000000000..7540e73a97
--- /dev/null
+++ b/spec/unit/resource/alternatives_spec.rb
@@ -0,0 +1,50 @@
+#
+# Author:: Tim Smith (<tsmith@chef.io>)
+# Copyright:: 2020, Chef Software 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 "spec_helper"
+
+describe Chef::Resource::Alternatives do
+  let(:node) { Chef::Node.new }
+  let(:events) { Chef::EventDispatch::Dispatcher.new }
+  let(:run_context) { Chef::RunContext.new(node, {}, events) }
+  let(:resource) { Chef::Resource::Alternatives.new("fakey_fakerton", run_context) }
+
+  it "the link_name property is the name_property" do
+    expect(resource.link_name).to eql("fakey_fakerton")
+  end
+
+  it "sets the default action as :install" do
+    expect(resource.action).to eql([:install])
+  end
+
+  it "coerces priority value to an Integer" do
+    resource.priority("1")
+    expect(resource.priority).to eql(1)
+  end
+
+  it "builds a default value for link based on link_name value" do
+    expect(resource.link).to eql("/usr/bin/fakey_fakerton")
+  end
+
+  it "supports :install, :auto, :refresh, and :remove actions" do
+    expect { resource.action :install }.not_to raise_error
+    expect { resource.action :auto }.not_to raise_error
+    expect { resource.action :refresh }.not_to raise_error
+    expect { resource.action :remove }.not_to raise_error
+  end
+end