Clear docker log files of given container of any invalid lines

clear_logs.py

"""
Usage: python3 clear_logs.py {{ full container ID }}

Clears the log file of any lines which are not valid JSON.
No error handling whatsoever. Use at own risk.
"""

import json
import pathlib
import shutil
import sys

template = '/var/lib/docker/containers/{}/{}-json.log'
out_dir = pathlib.Path('/tmp/cleared')
out_template = '{}-json.log'
container_id = sys.argv[1]

log_path = pathlib.Path(template.format(container_id, container_id))
out_path = pathlib.Path(out_dir / out_template.format(container_id))

out_dir.mkdir(exist_ok=True)

print(f'Attempting to clear {log_path}')
print(f'Output path: {out_path}')

skipped = 0

with open(log_path, 'r') as in_f, open(out_path, 'w') as out_f:
    for lno, line in enumerate(in_f.readlines()):
        try:
            parsed = json.loads(line)
            out_f.write(line)
        except:
            skipped += 1
            print('Skipping line no', lno, repr(line))

if skipped > 0:
    print('Copying cleared log file to original location')
    shutil.copy(out_path, log_path)

print(f'Done. Skipped ({skipped}) lines in total.')