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fence_mpath.py
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#!@PYTHON@ -tt
import sys
import stat
import re
import os
import time
import logging
import atexit
import ctypes
sys.path.append("@FENCEAGENTSLIBDIR@")
from fencing import fail_usage, run_command, atexit_handler, check_input, process_input, show_docs
from fencing import fence_action, all_opt, run_delay
def get_status(conn, options):
del conn
status = "off"
for dev in options["devices"]:
is_block_device(dev)
if options["--plug"] in get_registration_keys(options, dev):
status = "on"
else:
logging.debug("No registration for key "\
+ options["--plug"] + " on device " + dev + "\n")
if options["--action"] == "monitor":
dev_read(options)
return status
def set_status(conn, options):
del conn
count = 0
if options["--action"] == "on":
for dev in options["devices"]:
is_block_device(dev)
register_dev(options, dev)
if options["--plug"] not in get_registration_keys(options, dev):
count += 1
logging.debug("Failed to register key "\
+ options["--plug"] + " on device " + dev + "\n")
continue
dev_write(options, dev)
if get_reservation_key(options, dev) is None \
and not reserve_dev(options, dev) \
and get_reservation_key(options, dev) is None:
count += 1
logging.debug("Failed to create reservation (key="\
+ options["--plug"] + ", device=" + dev + ")\n")
else:
dev_keys = dev_read(options)
for dev in options["devices"]:
is_block_device(dev)
if options["--plug"] in get_registration_keys(options, dev):
preempt_abort(options, dev_keys[dev], dev)
for dev in options["devices"]:
if options["--plug"] in get_registration_keys(options, dev):
count += 1
logging.debug("Failed to remove key "\
+ options["--plug"] + " on device " + dev + "\n")
continue
if not get_reservation_key(options, dev):
count += 1
logging.debug("No reservation exists on device " + dev + "\n")
if count:
logging.error("Failed to verify " + str(count) + " device(s)")
sys.exit(1)
# run command, returns dict, ret["rc"] = exit code; ret["out"] = output;
# ret["err"] = error
def run_cmd(options, cmd):
ret = {}
if "--use-sudo" in options:
prefix = options["--sudo-path"] + " "
else:
prefix = ""
(ret["rc"], ret["out"], ret["err"]) = run_command(options,
prefix + cmd)
ret["out"] = "".join([i for i in ret["out"] if i is not None])
ret["err"] = "".join([i for i in ret["err"] if i is not None])
return ret
# check if device exist and is block device
def is_block_device(dev):
if not os.path.exists(dev):
fail_usage("Failed: device \"" + dev + "\" does not exist")
if not stat.S_ISBLK(os.stat(dev).st_mode):
fail_usage("Failed: device \"" + dev + "\" is not a block device")
# cancel registration
def preempt_abort(options, host, dev):
cmd = options["--mpathpersist-path"] + " -o --preempt-abort --prout-type=5 --param-rk=" + host +" --param-sark=" + options["--plug"] +" -d " + dev
return not bool(run_cmd(options, cmd)["rc"])
def register_dev(options, dev):
cmd = options["--mpathpersist-path"] + " -o --register --param-sark=" + options["--plug"] + " -d " + dev
#cmd return code != 0 but registration can be successful
return not bool(run_cmd(options, cmd)["rc"])
def reserve_dev(options, dev):
cmd = options["--mpathpersist-path"] + " -o --reserve --prout-type=5 --param-rk=" + options["--plug"] + " -d " + dev
return not bool(run_cmd(options, cmd)["rc"])
def get_reservation_key(options, dev):
cmd = options["--mpathpersist-path"] + " -i -r -d " + dev
out = run_cmd(options, cmd)
if out["rc"]:
fail_usage('Cannot get reservation key on device "' + dev
+ '": ' + out["err"])
match = re.search(r"\s+key\s*=\s*0x(\S+)\s+", out["out"], re.IGNORECASE)
return match.group(1) if match else None
def get_registration_keys(options, dev, fail=True):
keys = []
cmd = options["--mpathpersist-path"] + " -i -k -d " + dev
out = run_cmd(options, cmd)
if out["rc"]:
fail_usage('Cannot get registration keys on device "' + dev
+ '": ' + out["err"], fail)
if not fail:
return []
for line in out["out"].split("\n"):
match = re.search(r"\s+0x(\S+)\s*", line)
if match:
keys.append(match.group(1))
return keys
def dev_write(options, dev):
file_path = options["--store-path"] + "/mpath.devices"
if not os.path.isdir(options["--store-path"]):
os.makedirs(options["--store-path"])
try:
store_fh = open(file_path, "a+")
except IOError:
fail_usage("Failed: Cannot open file \""+ file_path + "\"")
store_fh.seek(0)
out = store_fh.read()
if not re.search(r"^{}\s+{}$".format(dev, options["--plug"]), out, flags=re.MULTILINE):
store_fh.write(dev + "\t" + options["--plug"] + "\n")
store_fh.close()
def dev_read(options, fail=True):
dev_key = {}
file_path = options["--store-path"] + "/mpath.devices"
try:
store_fh = open(file_path, "r")
except IOError:
if fail:
fail_usage("Failed: Cannot open file \"" + file_path + "\"")
else:
return None
# get not empty lines from file
for (device, key) in [line.strip().split() for line in store_fh if line.strip()]:
dev_key[device] = key
store_fh.close()
return dev_key
def mpath_check_get_options(options):
try:
f = open("/etc/sysconfig/stonith", "r")
except IOError:
return options
match = re.findall(r"^\s*(\S*)\s*=\s*(\S*)\s*", "".join(f.readlines()), re.MULTILINE)
for m in match:
options[m[0].lower()] = m[1].lower()
f.close()
return options
def mpath_check(hardreboot=False):
if len(sys.argv) >= 3 and sys.argv[1] == "repair":
return int(sys.argv[2])
options = {}
options["--mpathpersist-path"] = "/usr/sbin/mpathpersist"
options["--store-path"] = "@STORE_PATH@"
options["--power-timeout"] = "5"
options["retry"] = "0"
options["retry-sleep"] = "1"
options = mpath_check_get_options(options)
if "verbose" in options and options["verbose"] == "yes":
logging.getLogger().setLevel(logging.DEBUG)
devs = dev_read(options, fail=False)
if not devs:
if "--suppress-errors" not in options:
logging.error("No devices found")
return 0
for dev, key in list(devs.items()):
for n in range(int(options["retry"]) + 1):
if n > 0:
logging.debug("retry: " + str(n) + " of " + options["retry"])
if key in get_registration_keys(options, dev, fail=False):
logging.debug("key " + key + " registered with device " + dev)
return 0
else:
logging.debug("key " + key + " not registered with device " + dev)
if n < int(options["retry"]):
time.sleep(float(options["retry-sleep"]))
logging.debug("key " + key + " registered with any devices")
if hardreboot == True:
libc = ctypes.cdll['libc.so.6']
libc.reboot(0x1234567)
return 2
def define_new_opts():
all_opt["devices"] = {
"getopt" : "d:",
"longopt" : "devices",
"help" : "-d, --devices=[devices] List of devices to use for current operation",
"required" : "0",
"shortdesc" : "List of devices to use for current operation. Devices can \
be comma or space separated list of device-mapper multipath devices (eg. /dev/mapper/3600508b400105df70000e00000ac0000 or /dev/mapper/mpath1). \
Each device must support SCSI-3 persistent reservations.",
"order": 1
}
all_opt["key"] = {
"getopt" : "k:",
"longopt" : "key",
"help" : "-k, --key=[key] Replaced by -n, --plug",
"required" : "0",
"shortdesc" : "Replaced by port/-n/--plug",
"order": 1
}
all_opt["suppress-errors"] = {
"getopt" : "",
"longopt" : "suppress-errors",
"help" : "--suppress-errors Suppress error log. Suppresses error logging when run from the watchdog service before pacemaker starts.",
"required" : "0",
"shortdesc" : "Error log suppression.",
"order": 4
}
all_opt["mpathpersist_path"] = {
"getopt" : ":",
"longopt" : "mpathpersist-path",
"help" : "--mpathpersist-path=[path] Path to mpathpersist binary",
"required" : "0",
"shortdesc" : "Path to mpathpersist binary",
"default" : "@MPATH_PATH@",
"order": 200
}
all_opt["store_path"] = {
"getopt" : ":",
"longopt" : "store-path",
"help" : "--store-path=[path] Path to directory containing cached keys",
"required" : "0",
"shortdesc" : "Path to directory where fence agent can store information",
"default" : "@STORE_PATH@",
"order": 200
}
def main():
atexit.register(atexit_handler)
device_opt = ["no_login", "no_password", "devices", "key", "sudo", \
"fabric_fencing", "on_target", "store_path", \
"suppress-errors", "mpathpersist_path", "force_on", "port", "no_port"]
define_new_opts()
all_opt["port"]["required"] = "0"
all_opt["port"]["help"] = "-n, --plug=[key] Key to use for the current operation"
all_opt["port"]["shortdesc"] = "Key to use for the current operation. \
This key should be unique to a node and have to be written in \
/etc/multipath.conf. For the \"on\" action, the key specifies the key use to \
register the local node. For the \"off\" action, this key specifies the key to \
be removed from the device(s)."
# fence_mpath_check
if os.path.basename(sys.argv[0]) == "fence_mpath_check":
sys.exit(mpath_check())
elif os.path.basename(sys.argv[0]) == "fence_mpath_check_hardreboot":
sys.exit(mpath_check(hardreboot=True))
options = check_input(device_opt, process_input(device_opt), other_conditions=True)
# hack to remove list/list-status actions which are not supported
options["device_opt"] = [ o for o in options["device_opt"] if o != "separator" ]
# workaround to avoid regressions
if "--key" in options:
options["--plug"] = options["--key"]
del options["--key"]
elif "--help" not in options and options["--action"] in ["off", "on", \
"reboot", "status", "validate-all"] and "--plug" not in options:
stop_after_error = False if options["--action"] == "validate-all" else True
fail_usage("Failed: You have to enter plug number or machine identification", stop_after_error)
docs = {}
docs["shortdesc"] = "Fence agent for multipath persistent reservation"
docs["longdesc"] = "fence_mpath is an I/O Fencing agent that uses SCSI-3 \
persistent reservations to control access multipath devices. Underlying \
devices must support SCSI-3 persistent reservations (SPC-3 or greater) as \
well as the \"preempt-and-abort\" subcommand.\nThe fence_mpath agent works by \
having a unique key for each node that has to be set in /etc/multipath.conf. \
Once registered, a single node will become the reservation holder \
by creating a \"write exclusive, registrants only\" reservation on the \
device(s). The result is that only registered nodes may write to the \
device(s). When a node failure occurs, the fence_mpath agent will remove the \
key belonging to the failed node from the device(s). The failed node will no \
longer be able to write to the device(s). A manual reboot is required.\
\n.P\n\
When used as a watchdog device you can define e.g. retry=1, retry-sleep=2 and \
verbose=yes parameters in /etc/sysconfig/stonith if you have issues with it \
failing."
docs["vendorurl"] = "https://www.sourceware.org/dm/"
show_docs(options, docs)
run_delay(options)
# Input control BEGIN
if options["--action"] == "validate-all":
sys.exit(0)
if not ("--devices" in options and options["--devices"]):
fail_usage("Failed: No devices found")
options["devices"] = [d for d in re.split(r"\s*,\s*|\s+", options["--devices"].strip()) if d]
options["--plug"] = re.sub(r"^0x0*|^0+", "", options.get("--plug", ""))
# Input control END
result = fence_action(None, options, set_status, get_status)
sys.exit(result)
if __name__ == "__main__":
main()

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