Initialize label statistics to zero

The label statistics age gauges that keep their values. Currently
nodepool doesn't initialize the label based node statistics to
zero. Because of this any label state that shows up in the statistics
won't be reset to zero and nodepool is stopping to send updates to
this gauge. This leads to graphs that are mostly stuck to 1 if no
nodes are currently in this state.

This can be fixed by iterating over the supported labels and
initializing all states of them to zero.

Change-Id: I6c7f63f8f64a83b225386f6da567bfae5141be7b

nodepool/stats.py

@@ -104,6 +104,12 @@ class StatsReporter(object):
             key = 'nodepool.provider.%s.nodes.%s' % (provider.name, state)
             states[key] = 0
 
+        # Initialize label stats to 0
+        for label in provider.getSupportedLabels():
+            for state in zk.Node.VALID_STATES:
+                key = 'nodepool.label.%s.nodes.%s' % (label, state)
+                states[key] = 0
+
         for node in zk_conn.nodeIterator():
             # nodepool.nodes.STATE
             key = 'nodepool.nodes.%s' % node.state

nodepool/tests/fixtures/node_no_min_ready.yaml

@@ -10,6 +10,8 @@ zookeeper-servers:
 labels:
   - name: fake-label
     min-ready: 0
+  - name: fake-label2
+    min-ready: 0
 
 providers:
   - name: fake-provider
@@ -34,6 +36,10 @@ providers:
             diskimage: fake-image
             min-ram: 8192
             flavor-name: 'Fake'
+          - name: fake-label2
+            diskimage: fake-image
+            min-ram: 8192
+            flavor-name: 'Fake'
 
 diskimages:
   - name: fake-image

nodepool/tests/test_launcher.py

@@ -84,6 +84,28 @@ class TestLauncher(tests.DBTestCase):
         self.assertReportedStat('nodepool.label.fake-label.nodes.ready',
                                 value='1', kind='g')
 
+        # Verify that we correctly initialized unused label stats to 0
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.building',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.testing',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.ready',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.in-use',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.used',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.hold',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.deleting',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.failed',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.init',
+                                value='0', kind='g')
+        self.assertReportedStat('nodepool.label.fake-label2.nodes.aborted',
+                                value='0', kind='g')
+
     def test_node_assignment_order(self):
         """Test that nodes are assigned in the order requested"""
         configfile = self.setup_config('node_many_labels.yaml')

releasenotes/notes/label-stats-1059f87162e461e1.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    The nodes by label and state statistic gauges are now correctly reset to
+    zero if no node of a label and state exists.