In config.php
#----------------#
# Grafana Config #
#----------------#
$config['influxdb']['enable'] = true;
$config['influxdb']['transport'] = 'http'; # Default, other options: https, udp
$config['influxdb']['host'] = 'grafana.int.mydomain.net';
$config['influxdb']['port'] = '8086';
$config['influxdb']['db'] = 'librenms';
$config['influxdb']['username'] = 'grafana-user';
$config['influxdb']['password'] = '*******************';
$config['influxdb']['timeout'] = 0; # Optional
$config['influxdb']['verifySSL'] = false; # Optional