The config above is what I have as my config.
So the curl command is assuming anyone can write to influxdb, you can add the username and password to it like so:
curl -i -XPOST http://jeff:[email protected]:8086/write?db=HWDB --data-binary "HARDWARE,CPU=1 value=91"
I assume your config also has the following lines?
$config['influxdb']['username'] = 'jeff';
$config['influxdb']['password'] = 'jeffspw';