(FACT-2745) Add Linux xen fact

lib/facter/facts/linux/xen.rb

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+module Facts
+  module Linux
+    class Xen
+      FACT_NAME = 'xen'
+      ALIASES = 'xendomains'
+
+      def call_the_resolver
+        xen_type = check_virt_what || check_xen
+        return Facter::ResolvedFact.new(FACT_NAME, nil) if !xen_type || xen_type != 'xen0'
+
+        domains = Facter::Resolvers::Xen.resolve(:domains) || []
+
+        [Facter::ResolvedFact.new(FACT_NAME, { domains: domains }),
+         Facter::ResolvedFact.new(ALIASES, domains.entries.join(','), :legacy)]
+      end
+
+      def check_virt_what
+        Facter::Resolvers::VirtWhat.resolve(:vm)
+      end
+
+      def check_xen
+        Facter::Resolvers::Xen.resolve(:vm)
+      end
+    end
+  end
+end

lib/facter/resolvers/xen.rb

@@ -7,6 +7,8 @@ class Xen < BaseResolver
       @fact_list ||= {}
 
       XEN_PATH = '/proc/xen/capabilities'
+      XEN_TOOLSTACK = '/usr/lib/xen-common/bin/xen-toolstack'
+      XEN_COMMANDS = ['/usr/sbin/xl', '/usr/sbin/xm'].freeze
 
       class << self
         private
@@ -18,6 +20,7 @@ def post_resolve(fact_name)
         def detect_xen(fact_name)
           @fact_list[:vm] = detect_xen_type
           @fact_list[:privileged] = privileged?(@fact_list[:vm])
+          @fact_list[:domains] = detect_domains
 
           @fact_list[fact_name]
         end
@@ -33,6 +36,31 @@ def privileged?(xen_type)
           content = Util::FileHelper.safe_read(XEN_PATH, nil)
           content&.strip == 'control_d' || xen_type == 'xen0'
         end
+
+        def detect_domains
+          domains = []
+          xen_command = find_command
+          return unless xen_command
+
+          output = Facter::Core::Execution.execute("#{xen_command} list", logger: log)
+          return if output.empty?
+
+          output.each_line do |line|
+            next if line =~ /Domain-0|Name/
+
+            domain = line.match(/^([^\s]*)\s/)
+            domain = domain&.captures&.first
+            domains << domain if domain
+          end
+
+          domains
+        end
+
+        def find_command
+          return XEN_TOOLSTACK if File.exist?(XEN_TOOLSTACK)
+
+          XEN_COMMANDS.each { |command| return command if File.exist?(command) }
+        end
       end
     end
   end

spec/facter/facts/linux/xen_spec.rb

@@ -0,0 +1,117 @@
+# frozen_string_literal: true
+
+describe Facts::Linux::Xen do
+  describe '#call_the_resolver' do
+    subject(:fact) { Facts::Linux::Xen.new }
+
+    before do
+      allow(Facter::Resolvers::VirtWhat).to receive(:resolve).with(:vm).and_return(vm)
+      allow(Facter::Resolvers::Xen).to receive(:resolve).with(:domains).and_return(domains)
+    end
+
+    context 'when is xen privileged' do
+      let(:vm) { 'xen0' }
+      let(:domains) { %w[domain1 domain2] }
+
+      it 'calls Facter::Resolvers::VirtWhat' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::VirtWhat).to have_received(:resolve).with(:vm)
+      end
+
+      it 'calls Facter::Resolvers::Xen with :domains' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::Xen).to have_received(:resolve).with(:domains)
+      end
+
+      it 'returns xen fact' do
+        expect(fact.call_the_resolver).to be_an_instance_of(Array).and \
+          contain_exactly(an_object_having_attributes(name: 'xen', value: { 'domains' => domains }),
+                          an_object_having_attributes(name: 'xendomains',
+                                                      value: domains.entries.join(','), type: :legacy))
+      end
+    end
+
+    context 'when is xen privileged but there are no domains' do
+      let(:vm) { nil }
+      let(:domains) { [] }
+
+      before do
+        allow(Facter::Resolvers::Xen).to receive(:resolve).with(:vm).and_return('xen0')
+      end
+
+      it 'calls Facter::Resolvers::VirtWhat' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::VirtWhat).to have_received(:resolve).with(:vm)
+      end
+
+      it 'calls Facter::Resolvers::Xen with :vm' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::Xen).to have_received(:resolve).with(:vm)
+      end
+
+      it 'calls Facter::Resolvers::Xen with :domains' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::Xen).to have_received(:resolve).with(:domains)
+      end
+
+      it 'returns xen fact' do
+        expect(fact.call_the_resolver).to be_an_instance_of(Array).and \
+          contain_exactly(an_object_having_attributes(name: 'xen', value: { 'domains' => domains }),
+                          an_object_having_attributes(name: 'xendomains',
+                                                      value: domains.entries.join(','), type: :legacy))
+      end
+    end
+
+    context 'when is xen privileged but domains are nil' do
+      let(:vm) { nil }
+      let(:domains) { nil }
+      let(:result) { [] }
+
+      before do
+        allow(Facter::Resolvers::Xen).to receive(:resolve).with(:vm).and_return('xen0')
+      end
+
+      it 'calls Facter::Resolvers::VirtWhat' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::VirtWhat).to have_received(:resolve).with(:vm)
+      end
+
+      it 'calls Facter::Resolvers::Xen with :vm' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::Xen).to have_received(:resolve).with(:vm)
+      end
+
+      it 'calls Facter::Resolvers::Xen with :domains' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::Xen).to have_received(:resolve).with(:domains)
+      end
+
+      it 'returns xen fact' do
+        expect(fact.call_the_resolver).to be_an_instance_of(Array).and \
+          contain_exactly(an_object_having_attributes(name: 'xen', value: { 'domains' => result }),
+                          an_object_having_attributes(name: 'xendomains',
+                                                      value: result.entries.join(','), type: :legacy))
+      end
+    end
+
+    context 'when is xen unprivileged' do
+      let(:vm) { 'xenhvm' }
+      let(:domains) { nil }
+
+      it 'calls Facter::Resolvers::VirtWhat' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::VirtWhat).to have_received(:resolve).with(:vm)
+      end
+
+      it 'does not call Facter::Resolvers::Xen with :domains' do
+        fact.call_the_resolver
+        expect(Facter::Resolvers::Xen).not_to have_received(:resolve).with(:domains)
+      end
+
+      it 'returns nil fact' do
+        expect(fact.call_the_resolver).to be_an_instance_of(Facter::ResolvedFact).and \
+          have_attributes(name: 'xen', value: domains)
+      end
+    end
+  end
+end

spec/facter/resolvers/xen_spec.rb

@@ -5,16 +5,29 @@
 
   let(:proc_xen_file) { false }
   let(:xvda1_file) { false }
+  let(:log_spy) { instance_spy(Facter::Log) }
+  let(:domains) { '' }
 
   before do
+    xen_resolver.instance_variable_set(:@log, log_spy)
     allow(File).to receive(:exist?).with('/dev/xen/evtchn').and_return(evtchn_file)
     allow(File).to receive(:exist?).with('/proc/xen').and_return(proc_xen_file)
     allow(File).to receive(:exist?).with('/dev/xvda1').and_return(xvda1_file)
+    allow(File).to receive(:exist?).with('/usr/lib/xen-common/bin/xen-toolstack').and_return(false)
+    allow(File).to receive(:exist?).with('/usr/sbin/xl').and_return(false)
+    allow(File).to receive(:exist?).with('/usr/sbin/xm').and_return(true)
+    allow(Facter::Core::Execution).to receive(:execute).with('/usr/sbin/xm list', logger: log_spy).and_return(domains)
+
+    xen_resolver.invalidate_cache
+  end
+
+  after do
     xen_resolver.invalidate_cache
   end
 
   context 'when xen is privileged' do
     context 'when /dev/xen/evtchn exists' do
+      let(:domains) { load_fixture('xen_domains').read }
       let(:evtchn_file) { true }
 
       it 'returns xen0' do
@@ -28,6 +41,10 @@
       it 'does not check other files' do
         expect(File).not_to have_received(:exist?).with('/proc/xen')
       end
+
+      it 'returns domains' do
+        expect(xen_resolver.resolve(:domains)).to eq(%w[win linux])
+      end
     end
 
     context 'when /dev/xen/evtchn does not exist' do
@@ -64,5 +81,9 @@
     it 'detects xen as unprivileged' do
       expect(xen_resolver.resolve(:privileged)).to be_falsey
     end
+
+    it 'does not detect domains' do
+      expect(xen_resolver.resolve(:domains)).to be_nil
+    end
   end
 end

spec/fixtures/xen_domains

@@ -0,0 +1,4 @@
+Name                                        ID   Mem VCPUs      State   Time(s)
+Domain-0                                     0   750     4     r-----   11794.3
+win                                          1  1019     1     r-----       0.3
+linux                                        2  2048     2     r-----    5624.2