Grafana - forcing promtail to use hostname of the machine

Monitoring and Observability Grafana
#21

And service file

Type=simple
ExecStart=/usr/bin/promtail -positions.file /var/lib/promtail/positions.yml -config.file /etc/loki/promtail.yaml -config.expand-env=true
User=promtail
TimeoutStopSec=30s```
#22

And echo $HOSTNAME gives me the right hostname