Process Management

Introduction

Process managers ensure your application starts on boot, restarts on crash, and can be gracefully reloaded during deployments.

Key Concepts

Systemd: Modern Linux service manager.

Graceful Restart: Update without dropping connections.

Socket Activation: Start service on first request.

Deep Dive

Systemd Service

ini
# /etc/systemd/system/django.service
[Unit]
Description=Django
After=network.target

[Service]
User=www-data
WorkingDirectory=/var/www/myproject
EnvironmentFile=/var/www/myproject/.env
ExecStart=/var/www/myproject/venv/bin/gunicorn \
    --workers 4 \
    --bind unix:/run/gunicorn.sock \
    myproject.wsgi:application
Restart=on-failure

[Install]
WantedBy=multi-user.target

Service Commands

bash
sudo systemctl daemon-reload
sudo systemctl enable django
sudo systemctl start django
sudo systemctl reload django  # Graceful

Best Practices

1. Run as non-root: Use dedicated user like www-data.
2. Auto-restart on failure: Set Restart=on-failure.
3. Use socket files: More secure than TCP.

Summary

Systemd manages your application lifecycle. Use socket files, run as non-root, and enable auto-restart for reliability.