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reactive/namenode_ha_cluster.py

@@ -1,3 +1,4 @@
+from subprocess import check_output, CalledProcessError
 from charms.reactive import when
 from charms.reactive import when_not
 from charms.reactive import is_state
@@ -152,6 +153,23 @@ def init_ha_standby(datanode, cluster):
     set_state('namenode.started')
 
 
+@when('leadership.set.ha-initialized')
+@when_not('namenode.crontab')
+def register_crontab():
+    local_unit = hookenv.local_unit()
+    try:
+        crontab = check_output(['crontab', '-lu', 'hdfs'],
+                               universal_newlines=True)
+    except CalledProcessError:
+        crontab = ''
+    crontab += '*/1 * * * * ' \
+               'juju-run %s "PYTHONPATH=lib reactive/namenode_status.py"\n' % (
+                   local_unit)
+    check_output(['crontab', '-', '-u', 'hdfs'],
+                 input=crontab, universal_newlines=True)
+    set_state('namenode.crontab')
+
+
 # FIXME: The transition to active fails; uncertain if it would fail if done
 #        manually by the admin as well, or if it's just a timing issue; needs
 #        more testing.  It would be nice, though, if the transition to HA would

reactive/namenode_status.py

@@ -1,7 +1,9 @@
+#!/usr/bin/env python3
 from charms.reactive import when
 from charms.reactive import when_not
 from charms.reactive import when_any
 from charms.reactive import is_state
+from charms.reactive import RelationBase
 from charmhelpers.core import hookenv
 from jujubigdata import utils
 from charms.layer.apache_hadoop_namenode import get_cluster_nodes
@@ -48,18 +50,25 @@ def report_status(datanode):
         else:
             role = 'extra'
         if not degraded:
-            extra = '{}, with {} fail-over'.format(role, failover)
+            extra = 'HA {}, with {} fail-over'.format(role, failover)
         else:
             missing = ' and '.join(filter(None, [
                 'NameNode' if not clustered else None,
                 'JournalNodes' if not quorum else None,
                 'active' if not active else None,
                 'standby' if not standby else None,
             ]))
-            extra = 'degraded {} (missing: {}), with {} fail-over'.format(
+            extra = 'HA degraded {} (missing: {}), with {} fail-over'.format(
                 role, missing, failover)
     hookenv.status_set('active', 'Ready ({count} DataNode{s}, {extra})'.format(
         count=num_slaves,
         s='s' if num_slaves > 1 else '',
         extra=extra,
     ))
+
+
+if __name__ == '__main__':
+    if is_state('datanode.joined'):
+        report_status(RelationBase.from_state('datanode.joined'))
+    else:
+        report_blocked()