runtime error: index out of range in mineVersion on v0.8.0

[lahwaacz]

I'm getting this error on v0.8.0:

prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:30:40.463Z caller=main.go:94 level=info msg="Starting systemd_exporter" version="(version=, branch=, revision=)"
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:30:40.463Z caller=main.go:95 level=info msg="Build context" build_context="(go=go1.19.2, user=, date=)"
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:30:40.463Z caller=main.go:100 level=info msg="No devices specified, trying to load them automatically"
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:30:40.474Z caller=main.go:105 level=info msg="Found device" device=/dev/sda
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:30:40.488Z caller=main.go:128 level=info msg="Listening on" address=0.0.0.0:9633
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:30:40.490Z caller=tls_config.go:195 level=info msg="TLS is disabled." http2=false
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:40:45.346Z caller=readjson.go:69 level=warn msg="S.M.A.R.T. output reading" err="exit status 2"
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:40:45.346Z caller=readjson.go:122 level=error msg="Device open failed, device did not return an IDENTIFY DEVICE structure, or device is in a low-power mode"
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:40:45.346Z caller=main.go:57 level=error msg="Error collecting SMART data" err="smartctl returned bad data for device /dev/sda"
prometheus-smartctl-exporter[100066]: panic: runtime error: index out of range [0] with length 0
prometheus-smartctl-exporter[100066]: goroutine 57 [running]:
prometheus-smartctl-exporter[100066]: main.(*SMARTctlInfo).mineVersion(0xc0003a7e08)
prometheus-smartctl-exporter[100066]:         github.com/prometheus-community/smartctl_exporter/smartctlinfo.go:59 +0xba5
prometheus-smartctl-exporter[100066]: main.(*SMARTctlInfo).Collect(...)
prometheus-smartctl-exporter[100066]:         github.com/prometheus-community/smartctl_exporter/smartctlinfo.go:48
prometheus-smartctl-exporter[100066]: main.SMARTctlManagerCollector.Collect({{0x0, 0x0}, 0x0, {0xc000218e50, 0x1, 0x1}, {0x55fb044ea940, 0xc000242dc0}}, 0xc00036a060?)
prometheus-smartctl-exporter[100066]:         github.com/prometheus-community/smartctl_exporter/main.go:60 +0xd2
prometheus-smartctl-exporter[100066]: github.com/prometheus/client_golang/prometheus.(*wrappingCollector).Collect.func1()
prometheus-smartctl-exporter[100066]:         github.com/prometheus/[email protected]/prometheus/wrap.go:131 +0x2e
prometheus-smartctl-exporter[100066]: created by github.com/prometheus/client_golang/prometheus.(*wrappingCollector).Collect
prometheus-smartctl-exporter[100066]:         github.com/prometheus/[email protected]/prometheus/wrap.go:130 +0x8d

It seems that if there is no device after #74, there is no data for mineVersion to work?

[SuperQ]

Your actual error is this:

prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:40:45.346Z caller=readjson.go:122 level=error msg="Device open failed, device did not return an IDENTIFY DEVICE structure, or device is in a low-power mode"
prometheus-smartctl-exporter[100066]: ts=2022-10-09T08:40:45.346Z caller=main.go:57 level=error msg="Error collecting SMART data" err="smartctl returned bad data for device /dev/sda"

You will need to find out why your device is returning bad data.

[lahwaacz]

Hmm, so readSmartctl prints caller=readjson.go:69 level=warn msg="S.M.A.R.T. output reading" err="exit status 2" which means that the device is in standby mode. Then resultCodeIsOk prints caller=readjson.go:122 level=error msg="Device open failed, device did not return an IDENTIFY DEVICE structure, or device is in a low-power mode" and returns false. Then readData gets ok = false and treats the result as "bad data", so it prints level=error msg="Error collecting SMART data" err="smartctl returned bad data for device /dev/sda" and returns an empty json. Then the program continues, but fails in the case there is no other disk.

I admit this is rather weird case, since the root filesystem is mounted from /dev/sda and when the device goes into standby, the exporter's execution of the smartctl command does not wake it up.

[lahwaacz]

@SuperQ @k0ste any ideas? 🙏