FastAPI Deployment - Quick Reference Cheat Sheet

Initial Deployment

# 1. Upload your app code to /home/ubuntu/cardlabsv3.0
# 2. Upload deployment scripts
# 3. Configure
nano deploy.config

# 4. Deploy
chmod +x deploy_advanced.sh
./deploy_advanced.sh

Essential Commands

Service Management

# Start service
sudo systemctl start fastapi

# Stop service
sudo systemctl stop fastapi

# Restart service
sudo systemctl restart fastapi

# Check status
sudo systemctl status fastapi

# Enable auto-start on boot
sudo systemctl enable fastapi

View Logs

# Live logs (Ctrl+C to exit)
sudo journalctl -u fastapi -f

# Last 50 lines
sudo journalctl -u fastapi -n 50

# Only errors
sudo journalctl -u fastapi -p err -n 50

# Logs from today
sudo journalctl -u fastapi --since today

# Logs with timestamps
sudo journalctl -u fastapi -o short-iso

Update Code

# Quick update
cd /home/ubuntu/cardlabsv3.0
git pull
source venv/bin/activate
pip install -r requirements.txt
sudo systemctl restart fastapi

# Or use the script
./redeploy.sh

Database Operations

# Connect to PostgreSQL
sudo -u postgres psql

# Connect to specific database
sudo -u postgres psql -d cardlabs

# Backup database
sudo -u postgres pg_dump cardlabs > backup.sql

# Restore database
sudo -u postgres psql cardlabs < backup.sql

# PostgreSQL commands (inside psql):
\l                  # List databases
\c dbname           # Connect to database
\dt                 # List tables
\d tablename        # Describe table
\q                  # Quit

Nginx

# Test configuration
sudo nginx -t

# Reload configuration
sudo systemctl reload nginx

# Restart nginx
sudo systemctl restart nginx

# Check status
sudo systemctl status nginx

# View access logs
sudo tail -f /var/log/nginx/access.log

# View error logs
sudo tail -f /var/log/nginx/error.log

SSL/HTTPS

# View certificate info
sudo certbot certificates

# Test renewal
sudo certbot renew --dry-run

# Force renewal
sudo certbot renew --force-renewal

# Check auto-renewal timer
sudo systemctl status certbot.timer

🔧 Common Tasks

Edit Environment Variables

nano /home/ubuntu/cardlabsv3.0/.env
sudo systemctl restart fastapi

Update Python Dependencies

cd /home/ubuntu/cardlabsv3.0
source venv/bin/activate
pip install package-name
pip freeze > requirements.txt
sudo systemctl restart fastapi

Change Number of Workers

sudo nano /etc/systemd/system/fastapi.service
# Change -w 4 to desired number
sudo systemctl daemon-reload
sudo systemctl restart fastapi

View System Resources

# Memory
free -h

# Disk
df -h

# CPU
top
htop  # if installed

# Running processes
ps aux | grep gunicorn

Troubleshooting

Service Won't Start

# Check logs for errors
sudo journalctl -u fastapi -n 100 --no-pager

# Test manually
cd /home/ubuntu/cardlabsv3.0
source venv/bin/activate
python main.py

# Or test with gunicorn
gunicorn -w 1 -k uvicorn.workers.UvicornWorker main:app --bind 0.0.0.0:8000

Database Connection Issues

# Check if PostgreSQL is running
sudo systemctl status postgresql

# Test connection
sudo -u postgres psql -c "SELECT 1"

# Check .env file
cat /home/ubuntu/cardlabsv3.0/.env

502 Bad Gateway

# Check if app is running
sudo systemctl status fastapi

# Check nginx is running
sudo systemctl status nginx

# Test app directly
curl http://localhost:8000

# Check nginx error logs
sudo tail -f /var/log/nginx/error.log

High Memory Usage

# Check processes
ps aux --sort=-%mem | head -10

# Reduce workers in systemd service
sudo nano /etc/systemd/system/fastapi.service
# Change -w 4 to -w 2
sudo systemctl daemon-reload
sudo systemctl restart fastapi

Monitoring

Check if App is Responding

# Local test
curl http://localhost:8000

# Full test with headers
curl -I https://your-domain.com

# Response time
curl -w "@-" -o /dev/null -s https://your-domain.com <<'EOF'
     time_total:  %{time_total}s\n
EOF

Active Connections

# See active connections
sudo netstat -tulpn | grep :8000

# Count connections
sudo netstat -an | grep :8000 | wc -l

Security

Firewall Setup

sudo ufw allow 22
sudo ufw allow 80
sudo ufw allow 443
sudo ufw enable
sudo ufw status

Change Database Password

sudo -u postgres psql
ALTER USER postgres PASSWORD 'new-password';
\q

# Update .env file
nano /home/ubuntu/cardlabsv3.0/.env
# Change DATABASE_URL password
sudo systemctl restart fastapi

View Failed Login Attempts

sudo grep "Failed password" /var/log/auth.log | tail -20

Important File Locations

/home/ubuntu/cardlabsv3.0/          # Application directory
/home/ubuntu/cardlabsv3.0/.env      # Environment variables
/home/ubuntu/cardlabsv3.0/venv/     # Virtual environment

/etc/systemd/system/fastapi.service # Systemd service file
/etc/nginx/sites-available/fastapi  # Nginx configuration

/var/log/nginx/access.log           # Nginx access logs
/var/log/nginx/error.log            # Nginx error logs

/etc/letsencrypt/live/              # SSL certificates

Backup & Restore

Full Backup

# Backup database
sudo -u postgres pg_dump cardlabs > ~/backup_db_$(date +%Y%m%d).sql

# Backup application
tar -czf ~/backup_app_$(date +%Y%m%d).tar.gz /home/ubuntu/cardlabsv3.0

# Backup configs
sudo tar -czf ~/backup_configs_$(date +%Y%m%d).tar.gz \
  /etc/systemd/system/fastapi.service \
  /etc/nginx/sites-available/fastapi

Restore

# Restore database
sudo -u postgres psql cardlabs < ~/backup_db_20240101.sql

# Restore application
tar -xzf ~/backup_app_20240101.tar.gz -C /

Tips

1. Always check logs first when troubleshooting
2. Test changes before restarting in production
3. Backup before updates - use ./redeploy.sh which does this automatically
4. Monitor disk space - logs can fill up quickly
5. Keep dependencies updated but test in staging first
6. Use environment variables for sensitive data
7. Set up monitoring with tools like Datadog, New Relic, or simple cron jobs

Emergency Recovery

App is Down - Quick Fix

sudo systemctl restart fastapi
sudo systemctl restart nginx

Complete Reset

# Stop everything
sudo systemctl stop fastapi nginx

# Check for stuck processes
ps aux | grep gunicorn
sudo killall gunicorn

# Start fresh
sudo systemctl start fastapi
sudo systemctl start nginx

Rollback to Previous Version

cd /home/ubuntu/cardlabsv3.0
git log  # Find commit hash
git checkout <commit-hash>
./redeploy.sh