How to Deploy Django API without zero downtime?

I need to implement a zero-downtime CI/CD deployment pipeline for my Django API on an on-premises Linux server to ensure seamless updates without interrupting active users, similar to the previous maintenance-free setup.

You may want to try :
Deploy to a new directory -> Update symlink (current) -> Gracefully reload Gunicorn (kill -HUP) -> Keep Nginx active as a reverse proxy

Example:

1. Use a Versioned Directory Structure - Deploy each version into its own timestamped folder:

/var/www/myproject/
├── current -> /var/www/myproject/releases/2025-05-06-1230/
├── releases/
│   ├── 2025-05-06-1230/
│   ├── 2025-05-05-1700/
├── shared/  (media/, static/, .env etc.)

In your CI/CD pipeline (e.g., GitLab CI, Jenkins, or Bash script):

# Timestamped release path
RELEASE_DIR="/var/www/myproject/releases/$(date +%Y-%m-%d-%H%M)"
mkdir -p $RELEASE_DIR

# Clone or copy project files
git clone https://your-repo.git $RELEASE_DIR
cd $RELEASE_DIR

# Setup virtual environment
source /var/www/myproject/venv/bin/activate

# Install dependencies
pip install -r requirements.txt

# Migrate DB and collect static
python manage.py migrate --noinput
python manage.py collectstatic --noinput

# Point "current" symlink to new release
ln -sfn $RELEASE_DIR /var/www/myproject/current

# Reload Gunicorn gracefully
kill -HUP `cat /run/gunicorn.pid`

Use Gunicorn's --pid flag and HUP signal to gracefully reload:

gunicorn --pid /run/gunicorn.pid ...
kill -HUP `cat /run/gunicorn.pid`

Use Nginx to proxy requests to Gunicorn, which adds buffering and reliability:

location / {
    proxy_pass http://unix:/run/gunicorn.sock;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
}