Don't fail on non-valid json in cache files

Resolves: rhbz#1438096
Closes-Bug: #1678328

Change-Id: Iee1bb4a7769568cfd3bad8b23c9dff440679ac16
Co-Authored-By: Alex Schultz <aschultz@redhat.com>
(cherry picked from commit 8566ad549c)

os_collect_config/ec2.py

@@ -68,7 +68,11 @@ class Collector(object):
         cache_path = cache.get_path('ec2')
         if os.path.exists(cache_path):
             with open(cache_path) as f:
-                metadata = json.load(f)
+                try:
+                    metadata = json.load(f)
+                except ValueError as e:
+                    log.getLogger(__name__).warn(e)
+                    metadata = None
                 if metadata:
                     return [('ec2', metadata)]
 

os_collect_config/tests/test_ec2.py

@@ -133,6 +133,20 @@ class TestEc2(testtools.TestCase):
         self.assertRaises(exc.Ec2MetadataNotAvailable, collect_ec2.collect)
         self.assertIn('Forbidden', self.log.output)
 
+    @mock.patch.object(config_drive, 'config_drive')
+    def test_collect_ec2_invalid_cache(self, cd):
+        cd.return_value = None
+        collect.setup_conf()
+        cache_dir = self.useFixture(fixtures.TempDir())
+        self.addCleanup(cfg.CONF.reset)
+        cfg.CONF.set_override('cachedir', cache_dir.path)
+        ec2_path = os.path.join(cache_dir.path, 'ec2.json')
+        with open(ec2_path, 'w') as f:
+            f.write('')
+
+        ec2_md = ec2.Collector(requests_impl=FakeRequests).collect()
+        self.assertEqual([('ec2', META_DATA_RESOLVED)], ec2_md)
+
     @mock.patch.object(config_drive, 'config_drive')
     def test_collect_ec2_collected(self, cd):
         cd.return_value = None