On Tue, May 20, 2008 at 03:35:18PM -0400, Lon Hohberger wrote:
>
> On Tue, 2008-05-20 at 08:41 +0200, Darek Skorupa wrote:
> > > However, I'm having trouble finding how to integrate my script into
> > > the fence_node system. Is there a config file somewhere, or will I
> > > need to build a custom version of fence_node?
> > >
> > >
> > I think, you should copy fence_snmp script to /sbin folder and if script
> > will exit with '0' status fencing is successful in otherwise is
> > unsuccessful.
> >
>
> That's step one.
>
> The agent as noted doesn't appear to take arguments from STDIN. Try
> looking here for more information:
>
> http://sources.redhat.com/cluster/wiki/FenceAgentAPI
Awesome - thanks for the pointer. That makes so much more sense and
explains how fence_tool can introspect the options passed to the
particular fencer.
I've attached an updated version that follows the specifications at
the above link. I've got a two node cluster running configured with
it, though I haven't done any substantial testing yet.
Thanks for the help - feel free to use/distribute/forget about it :)
--
Ross Vandegrift
ross@xxxxxxxxxxx
"The good Christian should beware of mathematicians, and all those who
make empty prophecies. The danger already exists that the mathematicians
have made a covenant with the devil to darken the spirit and to confine
man in the bonds of Hell."
--St. Augustine, De Genesi ad Litteram, Book II, xviii, 37
#!/usr/bin/python
# fence_snmp.py: fabric fencing for RHCS based on setting a network interface
# to admin down. Will be used for iSCSI connections.
#
# Written by Ross Vandegrift <ross@xxxxxxxxxxx>
# Released into the public domain
import os
os.environ['PYSNMP_API_VERSION'] = 'v2'
import sys, getopt, random, socket
from pysnmp import role, v2c, asn1
ifAdminStatus = '.1.3.6.1.2.1.2.2.1.7.'
up = 1
down = 2
testing = 3
def usage():
line = '\t%s\t%s'
print ''
print 'This script fences a node by sending a command via SNMP to set'
print 'ifAdminStatus to down. It iss designed to kill node access'
print 'to the shared storage. It only supports SNMP v2c.'
print ''
print 'Usage: fence_snmp [options]'
print line % ('-h', '\tPrint usage')
print line % ('-V', '\tRun verbosely')
print line % ('-c [private]', 'Write community string to use')
print line % ('-a [hostname]', 'IP/hostname of SNMP agent')
print line % ('-i [index]', 'ifIndex entry of the port ')
print line % ('-o [action]', 'One of down, up, or status')
def vprint(v, s):
if v:
print s
def parseargs():
try:
opt, arg = getopt.getopt (sys.argv[1:], 'hVc:v:a:i:o:')
except getopt.GetoptError, e:
print str (e)
usage ()
sys.exit (-1)
comm = ipaddr = ifindex = option = verbose = None
for o, a in opt:
if o == '-h':
usage ()
sys.exit (-1)
if o == '-V':
verbose = True
if o == '-c':
comm = a
if o == '-a':
ipaddr = a
if o == '-i':
try:
ifindex = int(a)
except:
sys.stderr.write ('fence_snmp: ifIndex must be an integer\n')
usage ()
sys.exit (-1)
if o == '-o':
option = a
if option not in ('on', 'off', 'status'):
sys.stderr.write ('fence_snmp: option must be one of on, off, or status\n')
usage ()
sys.exit (-1)
if comm == None or ipaddr == None or ifindex == None \
or option == None:
sts.stderr.write ('All args are madatory!\n')
usage ()
sys.exit (-1)
return (comm, ipaddr, ifindex, option, verbose)
def parsestdin():
params = {}
for line in sys.stdin:
val = line.split('=')
if len (val) == 2:
params[val[0].strip ()] = val[1].strip ()
try:
comm = params['comm']
except:
sys.stdout.write ('fence_snmp: Error reading community string\n')
sys.exit (1)
try:
ipaddr = params['ipaddr']
except:
sys.stdout.write ('fence_snmp: Error reading destination IP/host\n')
sys.exit (1)
try:
ifindex = params['ifindex']
except:
sys.stdout.write ('fence_snmp: Error reading ifindex\n')
sys.exit (1)
try:
option = params['option']
except:
option = 'off'
return (comm, ipaddr, ifindex, option)
def snmpget (host, comm, oid):
req = v2c.GETREQUEST ()
encoded_oids = map (asn1.OBJECTID().encode, [oid,])
req['community'] = comm
tr = role.manager ((host, 161))
rsp = v2c.RESPONSE ()
(rawrsp, src) = tr.send_and_receive (req.encode (encoded_oids=encoded_oids))
rsp.decode (rawrsp)
if rsp['error_status']:
raise IOError('SNMP error while reading')
oids = map (lambda x: x[0], map(asn1.OBJECTID ().decode, rsp['encoded_oids']))
vals = map (lambda x: x[0] (), map(asn1.decode, rsp['encoded_vals']))
return vals[0]
def snmpset (host, comm, oid, type, value):
req = v2c.SETREQUEST (request_id=random.randint (1,2**16-1))
req['community'] = comm
tr = role.manager ((host, 161))
rsp = v2c.RESPONSE ()
encoded_oids = map (asn1.OBJECTID ().encode, [oid,])
encoded_vals = []
encoded_vals.append (eval ('asn1.' + type + '()').encode (value))
(rawrsp, src) = tr.send_and_receive (req.encode (encoded_oids=encoded_oids, encoded_vals=encoded_vals))
rsp.decode(rawrsp)
if rsp['error_status']:
raise IOError('SNMP error while setting')
oids = map (lambda x: x[0], map (asn1.OBJECTID().decode, rsp['encoded_oids']))
vals = map (lambda x: x[0] (), map (asn1.decode, rsp['encoded_vals']))
if vals[0] == value:
return vals[0]
else:
raise IOError('SNMP error while setting')
def main():
if len (sys.argv) > 1:
(comm, host, index, option, verbose) = parseargs ()
else:
verbose = False
(comm, host, index, option) = parsestdin ()
try:
switch = socket.gethostbyname (host)
except socket.gaierror, err:
vprint (verbose, 'fence_snmp: %s' % str (err[1]))
sys.exit(1)
if option == 'on':
value = up
elif option == 'off':
value = down
elif option == 'status':
value = None
if value:
# For option in (on, off) - write and verify
try:
r = snmpset (switch, comm, ifAdminStatus + str (index), 'INTEGER', value)
except:
sys.stderr.write ('fence_snmp: Error during snmp write\n')
sys.exit (1)
try:
s = int (snmpget (switch, comm, ifAdminStatus + str (index)))
except:
sys.stderr.write ('fence_snmp: Error during fence verification\n')
sys.exit (1)
if s == value:
vprint (verbose, 'fence_snmp: action %s sucessful' % option)
sys.exit (0)
else:
vprint (verbose, 'fence_snmp: action %s failed' % option)
sys.exit (1)
else: # status
try:
r = int (snmpget (switch, comm, ifAdminStatus + str (index)))
except:
sys.stderr.write ('fence_snmp: Error during snmp read\n')
sys.exit (1)
if r == up:
vprint (verbose, 'fence_snmp: Port is admin up')
sys.exit (0)
elif r == down:
vprint (verbose, 'fence_snmp: Port is admin down')
sys.exit (2)
elif r == testing:
vprint (verbose, 'fence_snmp: Port is admin testing')
sys.exit (2)
if __name__ == '__main__':
main()
--
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