bsdtar: check if tool path exists

Check if the configuration value of bsdtar_path does exist as a path
before trying to execute the binary.

Updated the tutorial reference of bsdtar to FreeBSD instead of Ubuntu.

Change-Id: Ieba5da2f330aa11c40cce6c2ae9de40155f33b07

Author: ader1990

cloudbaseinit/metadata/services/osconfigdrive/windows.py

@@ -106,9 +106,15 @@ def _write_iso_file(self, device, iso_file_path, iso_file_size):
                 offset += bytes_to_read
 
     def _extract_files_from_iso(self, iso_file_path):
-        args = [CONF.bsdtar_path, '-xf', iso_file_path,
-                '-C', self.target_path]
-        (out, err, exit_code) = self._osutils.execute_process(args, False)
+        bsdtar_args = [CONF.bsdtar_path, '-xf', iso_file_path,
+                       '-C', self.target_path]
+
+        if not os.path.exists(CONF.bsdtar_path):
+            raise exception.CloudbaseInitException(
+                'Bsdtar path "%s" does not exist.' % CONF.bsdtar_path)
+
+        (out, err, exit_code) = self._osutils.execute_process(bsdtar_args,
+                                                              False)
 
         if exit_code:
             raise exception.CloudbaseInitException(

cloudbaseinit/tests/metadata/services/osconfigdrive/test_windows.py

@@ -176,10 +176,13 @@ def test_write_iso_file(self):
         device.read.assert_has_calls(device_read_calls)
         OPEN.return_value.write.assert_has_calls(stream_write_calls)
 
-    def _test_extract_files_from_iso(self, exit_code):
+    @mock.patch('os.path.exists')
+    def _test_extract_files_from_iso(self, os_path_exists, exit_code,
+                                     enforce_os_path_exists=True):
         fake_path = os.path.join('fake', 'path')
         fake_target_path = os.path.join(fake_path, 'target')
         self._config_manager.target_path = fake_target_path
+        os_path_exists.return_code = enforce_os_path_exists
         args = [CONF.bsdtar_path, '-xf', fake_path, '-C', fake_target_path]
 
         self.osutils.execute_process.return_value = ('fake out', 'fake err',
@@ -199,6 +202,10 @@ def test_extract_files_from_iso(self):
     def test_extract_files_from_iso_fail(self):
         self._test_extract_files_from_iso(exit_code=1)
 
+    def test_extract_files_from_iso_fail_bsdtar_does_not_exist(self):
+        self._test_extract_files_from_iso(exit_code=1,
+                                          enforce_os_path_exists=False)
+
     @mock.patch('cloudbaseinit.metadata.services.osconfigdrive.windows.'
                 'WindowsConfigDriveManager._extract_files_from_iso')
     @mock.patch('cloudbaseinit.metadata.services.osconfigdrive.windows.'

doc/source/tutorial.rst

@@ -55,7 +55,7 @@ services and plugins ready for execution and also customizing user experience.
     # Which devices to inspect for a possible configuration drive (metadata).
     config_drive_raw_hhd=true
     config_drive_cdrom=true
-    # Path to tar implementation from Ubuntu.
+    # Path to tar implementation from FreeBSD: https://www.freebsd.org/cgi/man.cgi?tar(1).
     bsdtar_path=C:\Program Files (x86)\Cloudbase Solutions\Cloudbase-Init\bin\bsdtar.exe
     # Logging debugging level.
     verbose=true