Make 'blocked' status when node have no storage device

Currently there is an msg for no storage status on
ceph node. But it doesn't make this charm state
'blocked'.

is_storage_fine function has been created to check
storage devices on ceph_hooks.py and using it on
assess_status.

Change-Id: I790fde0280060fa220ee83de2ad2319ac2c77230
Closes-Bug: lp1424510

hooks/ceph_hooks.py

@@ -252,6 +252,13 @@ def get_devices():
     return devices
 
 
+def is_storage_fine():
+    for dev in get_devices():
+        if not os.path.exists(dev):
+            return False
+    return True
+
+
 @hooks.hook('mon-relation-joined')
 def mon_relation_joined():
     public_addr = get_public_addr()
@@ -476,6 +483,11 @@ def assess_status():
         status_set('waiting', 'Peer units detected, waiting for addresses')
         return
 
+    # check storage state
+    if not is_storage_fine():
+        status_set('blocked', 'No usable storage devices found')
+        return
+
     # active - bootstrapped + quorum status check
     if ceph.is_bootstrapped() and ceph.is_quorum():
         status_set('active', 'Unit is ready and clustered')

unit_tests/test_status.py

@@ -49,19 +49,33 @@ class ServiceStatusTestCase(test_utils.CharmTestCase):
         hooks.assess_status()
         self.status_set.assert_called_with('waiting', mock.ANY)
 
+    @mock.patch.object(hooks, 'is_storage_fine')
     @mock.patch.object(hooks, 'get_peer_units')
-    def test_assess_status_peers_complete_active(self, _peer_units):
+    def test_assess_status_peers_complete_active(self, _peer_units, _storage):
         _peer_units.return_value = ENOUGH_PEERS_COMPLETE
         self.ceph.is_bootstrapped.return_value = True
         self.ceph.is_quorum.return_value = True
+        _storage.return_value = True
         hooks.assess_status()
         self.status_set.assert_called_with('active', mock.ANY)
 
+    @mock.patch.object(hooks, 'is_storage_fine')
     @mock.patch.object(hooks, 'get_peer_units')
-    def test_assess_status_peers_complete_down(self, _peer_units):
+    def test_assess_status_peers_complete_down(self, _peer_units, _storage):
         _peer_units.return_value = ENOUGH_PEERS_COMPLETE
         self.ceph.is_bootstrapped.return_value = False
         self.ceph.is_quorum.return_value = False
+        _storage.return_value = False
+        hooks.assess_status()
+        self.status_set.assert_called_with('blocked', mock.ANY)
+
+    @mock.patch.object(hooks, 'is_storage_fine')
+    @mock.patch.object(hooks, 'get_peer_units')
+    def test_assess_status_storage_fail(self, _peer_units, _storage):
+        _peer_units.return_value = ENOUGH_PEERS_COMPLETE
+        self.ceph.is_bootstrapped.return_value = True
+        self.ceph.is_quorum.return_value = True
+        _storage.return_value = False
         hooks.assess_status()
         self.status_set.assert_called_with('blocked', mock.ANY)