Example of Python implementation of log backup daemon

Training background

Suppose you are an operation and maintenance engineer and need to develop a simple log backup daemon for the company's monitoring system. This process needs to meet the following requirements:

• Background operation: Leave the terminal and monitor log files in specified directories (such as /var/log/app/) for a long time.
• Automatic backup: Compress and backup the newly added log files to the /backup/logs/ directory every 5 minutes.
• Logging: Record the daemon's own operation log to /var/log/backup_daemon.log.
• System service: manages the start, stop and status view of the process through systemd.

Environmental preparation

Operating system: mainstream Linux distributions such as Ubuntu/CentOS

Python version: Python

Depend on installation:

# Make sure Python3 and pip are installedsudo apt install python3 python3-pip   # Ubuntu
sudo yum install python3 python3-pip   # CentOS

Training steps

Task 1: Write Python daemon code

Goal: Use Python to implement log monitoring and backup logic without manual processing.fork()。

Create scriptbackup_daemon.py

import os
import time
import logging
from datetime import datetime
import subprocess

#Configuration log(
    filename='/var/log/backup_daemon.log',
    level=,
    format='%(asctime)s - %(message)s',
    datefmt='%Y-%m-%d %H:%M:%S'
)

def backup_logs():
    log_dir = '/var/log/app'
    backup_dir = '/backup/logs'

    # traverse the log directory    for root, _, files in (log_dir):
        for file in files:
            src_path = (root, file)
            dest_path = (backup_dir, f"{file}.")

            # Check if it has been backed up            if not (dest_path):
                (f"Backing up {file}...")
                # Use tar to compress                try:
                    (
                        ['tar', '-czf', dest_path, src_path],
                        check=True,
                        stdout=,
                        stderr=
                    )
                except  as e:
                    (f"Failed to backup {file}: {e}")

if __name__ == "__main__":
    ("Daemon started.")
    while True:
        backup_logs()
        (300)  # Execute once in 5 minutes

Task 2: Configure the systemd service

Goal: Let Python scripts run in the background as services, without the need for in-code daemon logic.

Create a service file

sudo vim /etc/systemd/system/backup_daemon.service

Write service configuration

[Unit]
Description=Python Log Backup Daemon
After=

[Service]
Type=simple
ExecStart=/usr/bin/python3 /path/to/backup_daemon.py  # Modify to the actual script pathRestart=on-failure
RestartSec=5s
User=root
WorkingDirectory=/  # Optional: Set the working directory
[Install]
WantedBy=

Deploy and start the service

sudo systemctl daemon-reload
sudo systemctl start backup_daemon
sudo systemctl enable backup_daemon

Task 3: Testing and Verification

Generate test log files

sudo touch /var/log/app/

View backup results

ls /backup/logs  # It should be generated in 5 minutes

View daemon log

tail -f /var/log/backup_daemon.log

Task 4: Management Services

View status

systemctl status backup_daemon

Stop service

sudo systemctl stop backup_daemon

View systemd log

journalctl -u backup_daemon -f  # Real-time tracking logs

Training summary

Through this case, you will learn:

• Implement daemon logic using Python (no manualfork()）。
• passsystemdManage the background operation of Python scripts.
• Using PythonloggingThe module records the operation log.

Key points of knowledge

Advantages of Python:

• No need to deal with the underlying layerfork()andsetsid(), the code is more concise.
• usesubprocessModules can easily call system commands (such astar）。

systemd management:

• passType=simpleRun the foreground program directly,systemdAutomatic protection.
• Logs can be passedjournalctlUnified viewing.

Logging:

• Python built-inloggingThe module provides flexible log management.

Extended optimization suggestions

• Incremental backup: Records the backed-up file name or timestamp to avoid repeated compression.
• Exception handling: Addtry/exceptCapture file operation exception.
• Configuration file: UseconfigparserModule management path, interval time and other parameters.

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