All,
I recently had the need to be able to intelligently run crontab tasks in
a heartbeat cluster, so that they would only execute the task required
on the node where the heartbeat-managed resource was located. I wanted
to script to key off of a known nvpair that would always be (or most
likely be) within a particular resource's primitive tag, retrieve the
resource name, and then determine if it is running locally. Finally it
would return an exit status I could use from within the crontab script.
The below is written in Python. Feel free to use and modify, thought it
might be useful. I put extra print statements in to illustrate other
info that can be obtained from the xml.
#!/usr/bin/python
import xml.dom.minidom
from xml import xpath
import os, sys, string
argc = len(sys.argv)
if argc != 2:
print "Need cib.xml nvpair name to check"
sys.exit(-1)
nvpair = sys.argv[1]
os.system("/usr/sbin/cibadmin -Q > cibadmin.xml")
doc=xml.dom.minidom.parse("cibadmin.xml")
os.system("rm -f cibadmin.xml")
nv_list = xpath.Evaluate('//[EMAIL PROTECTED]"%s"]' % nvpair,doc)
if nv_list == []:
print "Invalid nvpair name given, not found"
sys.exit(-1)
nv_resource_node = nv_list[0]
print nv_resource_node.getAttribute("name")
print nv_resource_node.getAttribute("id")
print nv_resource_node.getAttribute("value")
print nv_resource_node.nodeName
tmpParent = nv_resource_node.parentNode
while tmpParent != None and tmpParent.nodeName != "primitive":
tmpParent = tmpParent.parentNode
if tmpParent != None:
print tmpParent.getAttribute("id")
resource_name = tmpParent.getAttribute("id")
else:
print "Did not find primitive parent"
doc.unlink()
sys.exit(-1)
doc.unlink()
resource_location=os.popen("/usr/sbin/crm_resource -W -r %s" %
resource_name).readline().strip()
print "resource location is :%s:" % resource_location
localhost_name=os.popen("uname -n").readline().strip()
print "local hostname is :%s:" % localhost_name
is_running_locally=resource_location.find(localhost_name)
if is_running_locally == -1:
print "Not running CRONTAB here, resource is elsewhere"
sys.exit(1)
else:
print "Running CRONTAB here, resource is local"
sys.exit(0)
An example of using it is:
#!/bin/sh
/u2/cfdb/bin/parse_cib.py pgdata
resource_status=$?
if [ $resource_status != 0 ]; then
echo "Resource not local, exiting"
exit 1
else
echo "Resource is local, continuing"
fi
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