Handle missing local collector directory

We currently explode if local collector is enabled with the data
directory missing. Changing this to a warning allows us to have this
turned on by default without greatly inconveniencing users.

Change-Id: I36364ba1a0706a5a2c820eadd526f2ba424ac665

os_collect_config/local.py

@@ -59,6 +59,11 @@ class Collector(object):
             raise exc.LocalMetadataNotAvailable
         final_content = []
         for local_path in cfg.CONF.local.path:
+            try:
+                os.stat(local_path)
+            except OSError:
+                logger.warning("%s not found. Skipping", local_path)
+                continue
             if _dest_looks_insecure(local_path):
                 raise exc.LocalMetadataNotAvailable
             for data_file in os.listdir(local_path):

os_collect_config/tests/test_local.py

@@ -140,3 +140,11 @@ class TestLocal(testtools.TestCase):
             badjson.write('{')
         self.assertRaises(exc.LocalMetadataNotAvailable, self._call_collect)
         self.assertIn('is not valid JSON', self.log.output)
+
+    def test_collect_local_path_nonexist(self):
+        cfg.CONF.set_override(name='path',
+                              override=['/this/doesnt/exist'],
+                              group='local')
+        local_md = self._call_collect()
+        self.assertThat(local_md, matchers.IsInstance(list))
+        self.assertEqual(0, len(local_md))