Call dib-run-parts from dib

After I149c345d38d761a49b3a6ccc4833482f09f1cd05 dib v2 does not export
dib-run-parts.  Since we have a "special" relationship with dib
internals, call the internal version.  This is fragile, but
practically dib is unlikely to break this.

Depends-On: I149c345d38d761a49b3a6ccc4833482f09f1cd05
Change-Id: Ibfe972208df40fa092b11b5419043524c903f1b4

instack/runner.py

@@ -26,6 +26,18 @@ from diskimage_builder import element_dependencies
 
 from instack import element
 
+# dib-run-parts has moved in dibv2 to an internal call.  We don't
+# really want to introduce a dependency on dib-utils here.  For v1
+# just call it from path.
+# Note this is fragile as dib considers this internal
+_DIB_RUN_PARTS = 'dib-run-parts'
+try:
+    import diskimage_builder.paths
+    _DIB_RUN_PARTS = os.path.join(diskimage_builder.paths.get_path('lib'),
+                                  'dib-run-parts')
+except ImportError:
+    pass
+
 
 LOG = logging.getLogger()
 
@@ -179,7 +191,7 @@ class ElementRunner(object):
                 LOG.debug("    Blacklisting %s" % blacklisted_script)
                 os.unlink(os.path.join(hook_dir, blacklisted_script))
 
-        command = ['dib-run-parts', hook_dir]
+        command = [_DIB_RUN_PARTS, hook_dir]
         if self.dry_run:
             LOG.info("    Dry Run specified, not running hook")
         else:

instack/tests/test_runner.py

@@ -118,7 +118,7 @@ class TestRunner(testtools.TestCase):
 
         self.assertEqual(1, mock_call.call_count)
         self.assertEqual(
-            ['dib-run-parts',
+            [runner._DIB_RUN_PARTS,
              os.path.join(self.runner.tmp_hook_dir, 'install.d')],
             mock_call.call_args_list[0][0][0])