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#!/usr/bin/env python3
"""
Collect systemd-journal log entries around time of daemon exit and coredumps.
"""
import datetime
import json
import logging
import pathlib
import shutil
import subprocess
import sys
TIMESPAN_BEFORE = 600 # s
TIMESPAN_AFTER = TIMESPAN_BEFORE
CURSOR_DIR = pathlib.Path('/var/lib/knot-resolver')
CURSOR_PATH = CURSOR_DIR / 'coredump_watcher.cursor'
class Timestamp:
def __init__(self, usec):
self.usec = int(usec)
@property
def unix(self):
return self.usec // 10**6
def __str__(self):
return datetime.datetime.utcfromtimestamp(self.unix).strftime('%Y-%m-%d_%H:%M:%S')
def __lt__(self, other):
return self.usec < other.usec
def __eq__(self, other):
return self.usec == other.usec
class Entry(dict):
@property
def timestamp(self):
usec = self.get('__REALTIME_TIMESTAMP')
if usec is None:
return None
return Timestamp(usec)
@property
def core_path(self):
filename = self.get('COREDUMP_FILENAME')
if filename is None:
return None
return pathlib.Path(filename)
def get_first(self, *keys):
for key in keys:
try:
return self[key]
except KeyError:
continue
return None
@property
def program(self):
return self.get_first('COREDUMP_UNIT', 'UNIT', '_SYSTEMD_UNIT', 'SYSLOG_IDENTIFIER')
@property
def pid(self):
return self.get_first('COREDUMP_PID', '_PID')
def save_cursor(cursor):
if cursor is None:
return
CURSOR_DIR.mkdir(parents=True, exist_ok=True)
with CURSOR_PATH.open('w') as curfile:
curfile.write(cursor)
logging.info('log cursor saved into %s, next run will skip old logs',
CURSOR_PATH)
def load_cursor():
try:
with CURSOR_PATH.open('r') as curfile:
logging.info('log cursor read from %s, skipping old logs',
CURSOR_PATH)
return curfile.read().strip()
except FileNotFoundError:
logging.info('log cursor file %s does not exist, parsing all logs',
CURSOR_PATH)
return None
def get_cursor():
journal_args = ['journalctl', '-o', 'json', '-n', '1']
with subprocess.Popen(
journal_args,
bufsize=1, # line buffering
universal_newlines=True,
stdout=subprocess.PIPE) as jproc:
stdout, _ = jproc.communicate()
data = json.loads(stdout)
entry = Entry(**data)
return entry.get('__CURSOR')
def read_journal(*args):
journal_args = [
'journalctl',
'-o', 'json',
'-u', 'kres*',
'-u', 'systemd-coredump*']
journal_args += args
with subprocess.Popen(
journal_args,
bufsize=1, # line buffering
universal_newlines=True,
stdout=subprocess.PIPE) as jproc:
for line in jproc.stdout:
data = json.loads(line)
yield Entry(**data)
def extract_logs(around_time, log_name):
start_time = Timestamp(around_time.usec - TIMESPAN_BEFORE * 10**6)
end_time = Timestamp(around_time.usec + TIMESPAN_AFTER * 10**6)
log_window = list(read_journal(
'--since', '@{}'.format(start_time.unix),
'--until', '@{}'.format(end_time.unix)))
with log_name.with_suffix('.json').open('w') as jsonf:
json.dump(log_window, jsonf, indent=4)
with log_name.with_suffix('.log').open('w') as logf:
logf.write('##### logs since {}\n'.format(start_time))
for entry in log_window:
if entry.timestamp == around_time:
logf.write('##### HERE #####\n')
logf.write('{t} {h} {prg}[{pid}]: {m}\n'.format(
t=entry.timestamp,
h=entry.get('_HOSTNAME'),
prg=entry.program,
pid=entry.pid,
m=entry.get('MESSAGE')))
logf.write('##### logs until {}\n'.format(end_time))
def main():
logging.basicConfig(level=logging.INFO)
if len(sys.argv) != 2:
sys.exit('Usage: {} <output log directory>'.format(sys.argv[0]))
outdir = pathlib.Path(sys.argv[1])
outdir.mkdir(parents=True, exist_ok=True)
cursor_previous = load_cursor()
cursor_at_start = get_cursor()
exit_times = []
coredumps = {}
filter_args = []
if cursor_previous is not None:
filter_args = ['--after-cursor', cursor_previous]
for entry in read_journal(*filter_args):
if 'EXIT_CODE' in entry:
logging.debug('exit@%s: %s', entry.timestamp, entry)
exit_times.append(entry.timestamp)
if 'COREDUMP_FILENAME' in entry:
logging.debug('coredump @ %s: %s', entry.timestamp, entry.core_path)
coredumps[entry.core_path] = entry.timestamp
exit_times.sort()
logging.debug('detected exits: %s', exit_times)
for exit_time in exit_times:
extract_logs(exit_time, outdir / str(exit_time))
coredumps_missing = 0
logging.debug('detected coredumps: %s', coredumps)
for core_path, core_time in coredumps.items():
core_name = core_path.name
out_path_prefix = (outdir / str(core_time))
extract_logs(core_time, out_path_prefix.with_suffix('.logs'))
try:
shutil.copy(
str(core_path),
str(out_path_prefix.with_suffix('.{}'.format(core_name))))
except FileNotFoundError as ex:
logging.error('coredump file %s cannot be copied: %s', core_path, ex)
coredumps_missing += 1
logging.info('wrote %d coredumps and %d logs snippets (%s coredumps missing)',
len(coredumps) - coredumps_missing, len(exit_times), coredumps_missing)
save_cursor(cursor_at_start)
if __name__ == '__main__':
main()
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