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fence_heuristics_ping.py
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fence_heuristics_ping.py

#!@PYTHON@ -tt
# The Following Agent Has Been Tested On:
#
# RHEL 7.4
#
import io
import re
import subprocess
import shlex
import sys, stat
import logging
import os
import atexit
sys.path.append("@FENCEAGENTSLIBDIR@")
from fencing import fail_usage, run_command, fence_action, all_opt
from fencing import atexit_handler, check_input, process_input, show_docs
from fencing import run_delay
def ping_test(con, options):
# Send pings to the targets
if options["--action"] == "on":
# we want unfencing to always succeed
return True
if not "--ping-targets" in options or options["--ping-targets"] == "":
# "off" was requested so fake "on" to provoke failure
logging.error("ping target required")
return False
timeout = int(options["--ping-timeout"])
count = int(options["--ping-count"])
interval = int(options["--ping-interval"])
good_required = int(options["--ping-good-count"])
maxfail = int(options["--ping-maxfail"])
targets = options["--ping-targets"].split(",")
exitcode = True
p = {}
failcount = 0
# search string for parsing the results of the ping-executable
packet_count = re.compile(r".*transmitted, ([0-9]*)( packets)? received.*")
# start a ping-process per target
for target in targets:
ping_path = '@PING_CMD@'
target_mangled = target
if target.startswith('inet6:'):
if '@PING6_CMD@' == '':
p[target] = None
continue
ping_path = '@PING6_CMD@'
target_mangled = target.split(':',2)[1]
elif target.startswith('inet:'):
ping_path = '@PING4_CMD@'
target_mangled = target.split(':',2)[1]
ping_cmd = "%s -n -q -W %d -c %d -i %d %s" % (
ping_path, timeout, count, interval, target_mangled)
logging.info("Running command: %s", ping_cmd)
try:
p[target] = subprocess.Popen(shlex.split(ping_cmd),
stdout=subprocess.PIPE);
except OSError:
p[target] = None
# collect the results of the ping-processes
for target in targets:
good = 0
if p[target] != None:
p[target].wait()
if p[target].returncode == 0:
for line in p[target].stdout:
searchres = packet_count.search(line.decode())
if searchres:
good = int(searchres.group(1))
break
if good >= good_required:
logging.info("ping target %s received %d of %d" \
% (target, good, count))
continue
failcount += 1
logging.info("ping target %s received %d of %d and thus failed"
% (target, good, count))
else:
failcount += 1
logging.error("ping target %s failed on OS level" % target)
if failcount > maxfail:
exitcode = False
return exitcode
def define_new_opts():
all_opt["ping_count"] = {
"getopt" : ":",
"longopt" : "ping-count",
"required" : "0",
"help" : "--ping-count=[number] Number of ping-probes to send",
"shortdesc" : "The number of ping-probes that is being sent per target",
"default" : "10",
"order" : 1
}
all_opt["ping_good_count"] = {
"getopt" : ":",
"longopt" : "ping-good-count",
"required" : "0",
"help" : "--ping-good-count=[number] Number of positive ping-probes required",
"shortdesc" : "The number of positive ping-probes required to account a target as available",
"default" : "8",
"order" : 1
}
all_opt["ping_interval"] = {
"getopt" : ":",
"longopt" : "ping-interval",
"required" : "0",
"help" : "--ping-interval=[seconds] Seconds between ping-probes",
"shortdesc" : "The interval in seconds between ping-probes",
"default" : "1",
"order" : 1
}
all_opt["ping_timeout"] = {
"getopt" : ":",
"longopt" : "ping-timeout",
"required" : "0",
"help" : "--ping-timeout=[seconds] Timeout for individual ping-probes",
"shortdesc" : "The timeout in seconds till an individual ping-probe is accounted as lost",
"default" : "2",
"order" : 1
}
all_opt["ping_maxfail"] = {
"getopt" : ":",
"longopt" : "ping-maxfail",
"required" : "0",
"help" : "--ping-maxfail=[number] Number of failed ping-targets allowed",
"shortdesc" : "The number of failed ping-targets to still account as overall success",
"default" : "0",
"order" : 1
}
all_opt["ping_targets"] = {
"getopt" : ":",
"longopt" : "ping-targets",
"required" : "1",
"help" : "--ping-targets=tgt1,[inet6:]tgt2 Comma separated list of ping-targets",
"shortdesc" : "A comma separated list of ping-targets (optionally prepended by 'inet:' or 'inet6:') to be probed",
"default" : "",
"order" : 1
}
def main():
device_opt = ["no_status", "no_password", "ping_count", "ping_good_count",
"ping_interval", "ping_timeout", "ping_maxfail", "ping_targets", "method"]
define_new_opts()
atexit.register(atexit_handler)
all_opt["method"]["default"] = "cycle"
all_opt["method"]["help"] = "-m, --method=[method] Method to fence (cycle|onoff) (Default: cycle)"
options = check_input(device_opt, process_input(device_opt))
docs = {}
docs["shortdesc"] = "Fence agent for ping-heuristic based fencing"
docs["longdesc"] = "fence_heuristics_ping uses ping-heuristics to control execution of another fence agent on the same fencing level.\
\n.P\n\
This is not a fence agent by itself! \
Its only purpose is to enable/disable another fence agent that lives on the same fencing level but after fence_heuristics_ping."
docs["vendorurl"] = ""
show_docs(options, docs)
# move ping-test to the end of the time-window set via --delay
# as to give the network time to settle after the incident that has
# caused fencing and have the results as current as possible
max_pingcheck = (int(options["--ping-count"]) - 1) * \
int(options["--ping-interval"]) + int(options["--ping-timeout"])
run_delay(options, reserve=max_pingcheck)
result = fence_action(\
None, \
options, \
None, \
None, \
reboot_cycle_fn = ping_test,
sync_set_power_fn = ping_test)
# execute the remaining delay
run_delay(options, result=result)
sys.exit(result)
if __name__ == "__main__":
main()

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