service resource: attempt a SysV fallback if SystemD unit file is not found (#2473)

* service resource: Fix no `.service` + systemd bug

This modifies the `enabled?` check to fallback to `sysv_service` in the
event that a `.service` file cannot be found.

For example: On Debian 8.7 the stock apache2 package does not deploy a
`.service` file but deploys a SysV style service. This causes
`systemctl is-enabled` to fail when the service is in fact enabled.

* Remove `cmd_stderr` and clean up `cmd_exit_1`
* Clean up `stderr` assignment using ternary

lib/resources/service.rb

@@ -250,7 +250,17 @@ module Inspec::Resources
     end
 
     def is_enabled?(service_name)
-      inspec.command("#{service_ctl} is-enabled #{service_name} --quiet").exit_status == 0
+      result = inspec.command("#{service_ctl} is-enabled #{service_name} --quiet")
+      return true if result.exit_status == 0
+
+      # Some systems may not have a `.service` file for a particular service
+      # which causes the `systemctl is-enabled` check to fail despite the
+      # service being enabled. In that event we fallback to `sysv_service`.
+      if result.stderr =~ /Failed to get.*No such file or directory/
+        return inspec.sysv_service(service_name).enabled?
+      end
+
+      false
     end
 
     def is_active?(service_name)

test/helper.rb

@@ -201,7 +201,10 @@ class MockLoader
       mock.mock_command('', '', '', 0)
     }
 
-    cmd_exit_1 = mock.mock_command('', '', '', 1)
+    cmd_exit_1 = lambda { |x = nil|
+      stderr = x.nil? ? '' : File.read(File.join(scriptpath, 'unit/mock/cmd', x))
+      mock.mock_command('', '', stderr, 1)
+    }
 
     mock.commands = {
       '' => empty.call,
@@ -234,7 +237,7 @@ class MockLoader
       'dpkg -s held-package' => cmd.call('dpkg-s-held-package'),
       'rpm -qia curl' => cmd.call('rpm-qia-curl'),
       'rpm -qia --dbpath /var/lib/fake_rpmdb curl' => cmd.call('rpm-qia-curl'),
-      'rpm -qia --dbpath /var/lib/rpmdb_does_not_exist curl' => cmd_exit_1,
+      'rpm -qia --dbpath /var/lib/rpmdb_does_not_exist curl' => cmd_exit_1.call,
       'pacman -Qi curl' => cmd.call('pacman-qi-curl'),
       'brew info --json=v1 curl' => cmd.call('brew-info--json-v1-curl'),
       '/usr/local/bin/brew info --json=v1 curl' => cmd.call('brew-info--json-v1-curl'),
@@ -248,7 +251,7 @@ class MockLoader
       "Rscript -e 'packageVersion(\"DBI\")'" => cmd.call('r-print-version'),
       "Rscript -e 'packageVersion(\"DoesNotExist\")'" => cmd.call('r-print-version-not-installed'),
       "perl -le 'eval \"require $ARGV[0]\" and print $ARGV[0]->VERSION or exit 1' DBD::Pg" => cmd.call('perl-print-version'),
-      "perl -le 'eval \"require $ARGV[0]\" and print $ARGV[0]->VERSION or exit 1' DOES::Not::Exist" => cmd_exit_1,
+      "perl -le 'eval \"require $ARGV[0]\" and print $ARGV[0]->VERSION or exit 1' DOES::Not::Exist" => cmd_exit_1.call,
       'pip show jinja2' => cmd.call('pip-show-jinja2'),
       'pip show django' => cmd.call('pip-show-django'),
       '/test/path/pip show django' => cmd.call('pip-show-non-standard-django'),
@@ -281,6 +284,7 @@ class MockLoader
       'initctl --version' => cmd.call('initctl--version'),
       # show ssh service Centos 7
       'systemctl show --all sshd' => cmd.call('systemctl-show-all-sshd'),
+      'systemctl show --all apache2' => cmd.call('systemctl-show-all-apache2'),
       '/path/to/systemctl show --all sshd' => cmd.call('systemctl-show-all-sshd'),
       'systemctl show --all dbus' => cmd.call('systemctl-show-all-dbus'),
       '/path/to/systemctl show --all dbus' => cmd.call('systemctl-show-all-dbus'),
@@ -454,13 +458,16 @@ class MockLoader
       "bash -c 'type \"firewall-cmd\"'" => cmd.call('firewall-cmd'),
       'rpm -qia firewalld' => cmd.call('pkg-info-firewalld'),
       'systemctl is-active sshd --quiet' => empty.call,
+      'systemctl is-active apache2 --quiet' => empty.call,
       'systemctl is-enabled sshd --quiet' => empty.call,
+      'systemctl is-enabled apache2 --quiet' => cmd_exit_1.call('systemctl-is-enabled-apache2-stderr'),
       'systemctl is-active dbus --quiet' => empty.call,
       'systemctl is-enabled dbus --quiet' => empty.call,
       '/path/to/systemctl is-active sshd --quiet' => empty.call,
       '/path/to/systemctl is-enabled sshd --quiet' => empty.call,
       '/usr/sbin/service sshd status' => empty.call,
       '/sbin/service sshd status' => empty.call,
+      'service apache2 status' => cmd_exit_1.call,
       'type "lsof"' => empty.call,
 
       # http resource - remote worker'

test/unit/mock/cmd/find-etc-rc-d-name-S

@@ -10,3 +10,7 @@
 /etc/rc.d/rc4.d/S08ip6tables
 /etc/rc.d/rc4.d/S90crond
 /etc/rc.d/rc4.d/S55sshd
+/etc/rc2.d/S02apache2
+/etc/rc3.d/S02apache2
+/etc/rc4.d/S02apache2
+/etc/rc5.d/S02apache2

test/unit/mock/cmd/ls-1-etc-init.d

@@ -1,2 +1,3 @@
 crond
 sshd
+apache2

test/unit/mock/cmd/systemctl-is-enabled-apache2-stderr

@@ -0,0 +1 @@
+Failed to get unit file state for apache2.service: No such file or directory

test/unit/mock/cmd/systemctl-show-all-apache2

@@ -0,0 +1,7 @@
+Id=apache2.service
+Names=apache2.service
+Description=LSB: Apache2 web server
+LoadState=loaded
+UnitFileState=
+SubState=running
+ActiveState=active

test/unit/resources/service_test.rb

@@ -268,6 +268,27 @@ describe 'Inspec::Resources::Service' do
     _(resource.params).must_equal params
   end
 
+  # debian 8 with systemd but no service file
+  it 'gets the correct service info when the `.service` file is missing' do
+    resource = MockLoader.new(:debian8).load_resource('service', 'apache2')
+    params = Hashie::Mash.new(
+      'ActiveState'   => 'active',
+      'Description'   => 'LSB: Apache2 web server',
+      'Id'            => 'apache2.service',
+      'LoadState'     => 'loaded',
+      'Names'         => 'apache2.service',
+      'SubState'      => 'running',
+      'UnitFileState' => ''
+    )
+    _(resource.type).must_equal 'systemd'
+    _(resource.name).must_equal 'apache2.service'
+    _(resource.description).must_equal 'LSB: Apache2 web server'
+    _(resource.installed?).must_equal true
+    _(resource.enabled?).must_equal true
+    _(resource.running?).must_equal true
+    _(resource.params).must_equal params
+  end
+
   # macos test
   it 'verify mac osx service parsing' do
     resource = MockLoader.new(:osx104).load_resource('service', 'ssh')