Setup a Redis service.

APT Based OS RPM Based OS

sudo apt update
sudo apt install -y redis-server
sudo systemctl enable redis-server.service --now

sudo dnf update
sudo dnf install -y redis
sudo systemctl enable redis.service --now

Once Redis is available you can update your systemd unit service with the new enviromet variable CACHE_REDIS_URL pointing to redis://localhost:6379/1:

[Unit]
Description=Cacao Accounting service.
After=syslog.target network.target

[Service]
Type=simple
Restart=on-failure
RestartSec=5
Environment="CACAO_KEY=hajkañdkjda455654ASSDAFCAFADASDÑÑÑÑÑÑññññññlkadjasdkldaldkd"
Environment="CACAO_DB=protocol+driver://user:password@host:port/dbname"
Environment="CACHE_REDIS_URL= redis://localhost:6379/1"
ExecStart=/opt/cacao-accounting/venv/bin/cacaoctl serve

[Install]
WantedBy=multi-user.target