Implement support for fetching hddtemp data

[mendelgusmao]

Here's a basic implementation for getting temperature data from disks using hddtemp

[sparrc]

why did you add an hddtemp build tag?

[mendelgusmao]

Got it. I'll update asap.

[mendelgusmao]

Fixed.

amend + push -f

[sparrc]

Looks good, but I noticed that go-hddtemp: https://github.com/MendelGusmao/go-hddtemp/blob/master/hddtemp.go is only ~60 lines of code.

Could you just copy hddtemp.go (and hddtemp_test.go) in-repo? You can add them with the license file in a directory, or put the license at the top of the file in a comment.

[mendelgusmao]

Fine, @sparrc ! Just pushed a modified commit according to your suggestions.

[sparrc]

Thanks @mendelgusmao. Am I correct in assuming that this requires that hddtemp is running as a daemon on the target system? Is this a common approach or would simply forking the hddtemp command and parsing the output suffice?

[mendelgusmao]

Yes. It's the common approach because hddtemp requires root access for gathering the data from the disks.

[sparrc]

this looks good, but you'll need to write a README: https://github.com/influxdata/telegraf/blob/master/CONTRIBUTING.md#steps-for-contributing

[mendelgusmao]

OK. I'll provide one.

[mendelgusmao]

Done!

[sparrc]

please rebase as well! 🙏

[mendelgusmao]

Done too.

[sparrc]

thanks @mendelgusmao