Add a new fab task to switch computes to new collector during ISSU

This commit is to add new fab task to change the config files of all processes
on the compute node to point to new collector during ISSU process. This switch
should be done once the controllers are upgraded to v2, but before the computes
are upgraded to v2.

Change-Id: I89a6931d7078d50cec245b1dde7d96d81f33611f
Closes-Bug: #1675122

fabfile/tasks/issu_process.py

@@ -20,6 +20,34 @@
 issu_process_bash_file="issu_process.sh" 
 issu_process_bash_path="/opt/contrail/utils/issu_process.sh"
 
+@task
+@roles('compute')
+def issu_contrail_switch_collector_in_compute():
+    """Migrate the contrail compute nodes to new collector."""
+    execute("issu_contrail_switch_collector_in_compute_node", env.host_string)
+
+@task
+def issu_contrail_switch_collector_in_compute_node(*args):
+    num_collectors = len(env.roledefs['collector'])
+    if num_collectors >= 2:
+        max_collectors = 2
+    else:
+        max_collectors = 1
+    import random
+    host_num = random.randint(0,num_collectors-1)
+    for host in args:
+        collector_list = ''
+        with settings(host_string=host):
+            for i in range(0, max_collectors):
+                collector_list += "%s:8086 " %(hstr_to_ip(get_control_host_string(env.roledefs['collector'][host_num])))
+                host_num = (host_num + 1) % num_collectors
+            import glob
+            file_list = glob.glob('/etc/contrail/contrail-tor-agent*.conf')
+            file_list.append('/etc/contrail/contrail-vrouter-agent.conf')
+            for cfile in file_list:
+                run('openstack-config --set %s DEFAULT collectors %s' % (cfile, collector_list))
+            run('openstack-config --set /etc/contrail/contrail-vrouter-nodemgr.conf COLLECTOR server_list %s' % (collector_list))
+
 @task
 @roles('compute')
 def issu_contrail_switch_compute(discovery_ip):