Change the label of devstack nodes on use.

Instead of disconnecting then node, change the label to
"devstack-used", which is a label we will never use for a job.
That way the node will not be re-used, but we don't get a warning
in the job console output about the node going offline.

Also, make sure the nodes are created for exclusive use
(tied jobs only).

Change-Id: Ib162d78baee17452cec13c150235f3584737d3c3

devstack-vm-inprogress.py

@@ -29,11 +29,13 @@ import myjenkins
 import vmdatabase
 import utils
 import novaclient
+import re
 
 NODE_NAME = sys.argv[1]
 DEVSTACK_GATE_SECURE_CONFIG = os.environ.get('DEVSTACK_GATE_SECURE_CONFIG', 
                                              os.path.expanduser('~/devstack-gate-secure.conf'))
 
+LABEL_RE = re.compile(r'<label>.*</label>')
 
 def main():
     db = vmdatabase.VMDatabase()
@@ -51,7 +53,9 @@ def main():
 
     if machine.jenkins_name:
         if jenkins.node_exists(machine.jenkins_name):
-            jenkins.disable_node(machine.jenkins_name, "Devstack build started")
+            config = jenkins.get_node_config(machine.jenkins_name)
+            config = LABEL_RE.sub('<label>devstack-used</label>', config)
+            jenkins.reconfig_node(machine.jenkins_name, config)
             
 
 if __name__ == '__main__':

devstack-vm-launch.py

@@ -91,6 +91,7 @@ def create_jenkins_node(jenkins, machine):
                             nodeDescription='Dynamic single use %s slave for devstack' % machine.base_image.name,
                             remoteFS='/home/jenkins',
                             labels='%sdevstack-%s' % (DEVSTACK_GATE_PREFIX, machine.base_image.name),
+                            exclusive=True,
                             launcher='hudson.plugins.sshslaves.SSHLauncher',
                             launcher_params = {'port': 22, 'username': 'jenkins', 
                                                'privatekey': '/var/lib/jenkins/.ssh/id_rsa',

myjenkins.py

@@ -5,6 +5,7 @@ import urllib2
 from jenkins import JenkinsException, NODE_TYPE, CREATE_NODE
 
 TOGGLE_OFFLINE = '/computer/%(name)s/toggleOffline?offlineMessage=%(msg)s'
+CONFIG_NODE = '/computer/%(name)s/config.xml'
 
 class Jenkins(jenkins.Jenkins):
     def disable_node(self, name, msg=''):
@@ -34,6 +35,25 @@ class Jenkins(jenkins.Jenkins):
         msg = ''
         self.jenkins_open(urllib2.Request(self.server + TOGGLE_OFFLINE%locals()))
 
+    def get_node_config(self, name):
+        '''
+        Get the configuration for a node.
+        
+        :param name: Jenkins node name, ``str``
+        '''
+        get_config_url = self.server + CONFIG_NODE%locals()
+        return self.jenkins_open(urllib2.Request(get_config_url))
+
+    def reconfig_node(self, name, config_xml):
+        '''
+        Change the configuration for an existing node.
+        
+        :param name: Jenkins node name, ``str``
+        :param config_xml: New XML configuration, ``str``
+        '''
+        headers = {'Content-Type': 'text/xml'}
+        reconfig_url = self.server + CONFIG_NODE%locals()
+        self.jenkins_open(urllib2.Request(reconfig_url, config_xml, headers))
 
     def create_node(self, name, numExecutors=2, nodeDescription=None,
                     remoteFS='/var/lib/jenkins', labels=None, exclusive=False,