sharder: downgrade 'no data dirs' warning to info

Previously if the sharder found no 'containers' directory on any
device then it would emit a warning. This can be a distraction when in
normal operation the sharder daemon is run on all nodes including
those not in the container ring. This patch clarifies the log message
and downgrades it to info level:

  INFO: Found no containers directories

The change also fixes the intermittent failure of the probe test
test_delete_root_reclaim in test/probe/test_sharder.pr. The test
asserts that no warning logs are emitted, but would previously fail if
no containers were created on one of the devices, since the 'Found no
data dirs' warning would be emitted.

Change-Id: I97f7aa790c225ffd72b77a3fc1a6ef41f72df13e

2 files changed, 24 insertions, 1 deletions

diff --git a/swift/container/sharder.py b/swift/container/sharder.py
index d577f0316..dfcc34f2a 100644
--- a/swift/container/sharder.py
+++ b/swift/container/sharder.py
@@ -1872,7 +1872,7 @@ class ContainerSharder(ContainerReplicator):
                     partitions_to_shard)
                 dirs.append((datadir, node, part_filt))
         if not dirs:
-            self.logger.warning('Found no data dirs!')
+            self.logger.info('Found no containers directories')
         for part, path, node in self.roundrobin_datadirs(dirs):
             # NB: get_part_nodes always provides an 'index' key;
             # this will be used in leader selection
diff --git a/test/unit/container/test_sharder.py b/test/unit/container/test_sharder.py
index c89f0eedf..946daeb23 100644
--- a/test/unit/container/test_sharder.py
+++ b/test/unit/container/test_sharder.py
@@ -805,6 +805,29 @@ class TestSharder(BaseTestSharder):
             self._assert_stats(
                 expected_in_progress_stats, sharder, 'sharding_in_progress')
 
+    def test_one_shard_cycle_no_containers(self):
+        conf = {'recon_cache_path': self.tempdir,
+                'devices': self.tempdir,
+                'mount_check': False}
+
+        with self._mock_sharder(conf) as sharder:
+            for dev in sharder.ring.devs:
+                os.mkdir(os.path.join(self.tempdir, dev['device']))
+            with mock.patch('swift.container.sharder.is_local_device',
+                            return_value=True):
+                sharder._one_shard_cycle(Everything(), Everything())
+        self.assertEqual([], sharder.logger.get_lines_for_level('warning'))
+        self.assertIn('Found no containers directories',
+                      sharder.logger.get_lines_for_level('info'))
+        with self._mock_sharder(conf) as sharder:
+            os.mkdir(os.path.join(self.tempdir, dev['device'], 'containers'))
+            with mock.patch('swift.container.sharder.is_local_device',
+                            return_value=True):
+                sharder._one_shard_cycle(Everything(), Everything())
+        self.assertEqual([], sharder.logger.get_lines_for_level('warning'))
+        self.assertNotIn('Found no containers directories',
+                         sharder.logger.get_lines_for_level('info'))
+
     def test_ratelimited_roundrobin(self):
         n_databases = 100