def _get_metrics(hosts, metrics, data=None):
"""Retrieve host metrics using SSH if necessary.
Note hosts will not appear in the returned results if:
* They are not contactable.
* There is an error in the command which returns the results.
Args:
hosts (list):
List of host fqdns.
metrics (list):
List in the form [(function, arg1, arg2, ...), ...]
data (dict):
Used for logging success/fail outcomes of the form {host: {}}
Examples:
Command failure:
>>> _get_metrics(['localhost'], [['elephant']])
({}, {'localhost': {'get_metrics': 'Command failed (exit: 1)'}})
Returns:
dict - {host: {(function, arg1, arg2, ...): result}}
"""
host_stats = {}
proc_map = {}
if not data:
data = {host: dict() for host in hosts}
# Start up commands on hosts
cmd = ['psutil']
kwargs = {'stdin_str': json.dumps(metrics), 'capture_process': True}
for host in hosts:
if is_remote_host(host):
proc_map[host] = remote_cylc_cmd(cmd, host=host, **kwargs)
else:
proc_map[host] = run_cmd(['cylc'] + cmd, **kwargs)
# Collect results from commands
while proc_map:
for host, proc in list(proc_map.copy().items()):
if proc.poll() is None:
continue
del proc_map[host]
out, err = (f.decode() for f in proc.communicate())
if proc.wait():
# Command failed in verbose/debug mode
LOG.warning('Could not evaluate "%s" (return code %d)\n%s',
host, proc.returncode, err)
data[host]['get_metrics'] = (
f'Command failed (exit: {proc.returncode})')
else:
host_stats[host] = dict(
zip(
metrics,
# convert JSON dicts -> namedtuples
_deserialise(metrics, parse_dirty_json(out))))
sleep(0.01)
return host_stats, data
def _psutil(metrics_json):
metrics = parse_dirty_json(metrics_json)
ret = [getattr(psutil, key[0])(*key[1:]) for key in metrics]
# serialise
for ind, item in enumerate(ret):
if hasattr(item, '_asdict'):
ret[ind] = item._asdict()
return ret
def main(parser, options):
metrics = parse_dirty_json(sys.stdin.read())
ret = [getattr(psutil, key[0])(*key[1:]) for key in metrics]
# serialise
for ind, item in enumerate(ret):
if hasattr(item, '_asdict'):
ret[ind] = item._asdict()
print(json.dumps(ret))
def _psutil(metrics_json):
metrics = parse_dirty_json(metrics_json)
methods = [getattr(psutil, key[0]) for key in metrics]
try:
ret = [method(*key[1:]) for key, method in zip(metrics, methods)]
except Exception as exc:
# error extracting metrics from psutil e.g:
# * requesting a method which does not exist
# * requesting information on a resource which does not exist
print(exc, file=sys.stderr)
sys.exit(2)
# serialise
for ind, item in enumerate(ret):
if hasattr(item, '_asdict'):
ret[ind] = item._asdict()
elif hasattr(item, 'as_dict'):
ret[ind] = item.as_dict()
return ret
