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Systemctl Service Logs Setup Using Logrotate

This guide explains how to set up log rotation for a service managed by systemctl using logrotate.

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Service Setup in systemctl

First, create a systemctl service configuration for your application. Below is an example configuration file for a service named app: 
[Unit]
Description=app
After=network.target

[Service]
Type=simple
User=ubuntu
Group=ubuntu
StandardOutput=append:/var/log/app/app.log
StandardError=append:/var/log/app/app.log
WorkingDirectory=/var/www/app
ExecStart=/var/www/app/main
Restart=always

[Install]
WantedBy=multi-user.target
This configuration:
  • Defines the service with Description and After directives.
  • Redirects standard output and error to /var/log/app/app.log.
  • Sets the working directory and the command to start the service.
  • Configures the service to always restart if it fails.

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Log Rotation Setup

To manage log rotation for the service logs, configure logrotate:
  1. Create a Logrotate Configuration File Edit or create the logrotate configuration file for your service: 
    sudo nano /etc/logrotate.d/app
    Add the following configuration: 
    /var/log/app/app.log {
    daily
    missingok
    rotate 7
    compress
    delaycompress
    notifempty
    create 0640 root root
    sharedscripts
    postrotate
        systemctl reload app.service > /dev/null 2>&1 || true
    endscript
}
    This configuration:
    • Rotates the log file daily.
    • Keeps 7 rotated log files before deleting the oldest.
    • Compresses old logs.
    • Skips empty logs.
    • Creates new log files with specific permissions and ownership.
    • Runs a script to reload the service after rotation.
  2. Prepare Log File and Directory Ensure the log file and directory have the correct permissions: 
    sudo chmod 644 /var/log/app/app.log
sudo chown root:root /var/log/app/app.log
    Ensure the directory has appropriate permissions: 
    sudo chmod 755 /var/log/app/
    Create the log file if it doesn’t exist: 
    sudo touch /var/log/app/app.log
    Restart the service to ensure it is writing logs: 
    sudo systemctl restart app.service
  3. Verify Logrotate Functionality Check the logrotate status file to confirm that the log file is tracked: 
    cat /var/lib/logrotate/status
    Run logrotate in verbose mode to see detailed output: 
    sudo logrotate -v /etc/logrotate.d/app
    Run logrotate in debug mode to understand why it might not be working: 
    sudo logrotate -d /etc/logrotate.d/app
  4. Manually Trigger Log Rotation Force a log rotation to test the setup: 
    sudo logrotate -f /etc/logrotate.d/app
By following these steps, you will set up log rotation for your service logs, ensuring they are managed and rotated daily.
This document provides a complete setup for managing and rotating logs for a service using logrotate. Adjust the paths and filenames according to your specific requirements.