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Systemctl Service Logs Setup Using Logrotate

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Service Setup in systemctl

[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

• 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

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
   

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.