[Unit]
Description=My App daemon
After=network.target postgresql.service
Wants=postgresql.service

[Service]
EnvironmentFile=/etc/sysconfig/my-app
WorkingDirectory=/opt/my-app/ # <- this is where your app lives
User=root
Group=root
Type=simple
ExecStart=/usr/bin/python server.py # <- this starts your app
Restart=always
RestartSec=5s

[Install]
WantedBy=multi-user.target

DB_HOST=localhost
DB_USER=postgres
DB_PASSWORD=postgres
DB_NAME=postgres

service my-app start
service my-app stop
service my-app restart

journalctl -u my-app -e