Handle thermal zones which return ENODATA for temp #293
Description
This is linked to prometheus/node_exporter#1703 - full details to reproduce are there.
I have a system with 5 thermal zones. However one of them returns ENODATA for the temp field:
# cat /sys/class/thermal/thermal_zone*/temp
27800
29800
41000
53000
cat: /sys/class/thermal/thermal_zone4/temp: No data available
# cat /sys/class/thermal/thermal_zone4/type
iwlwifi_1
# cat /sys/class/thermal/thermal_zone4/policy
step_wise
# cat /sys/class/thermal/thermal_zone4/temp
cat: /sys/class/thermal/thermal_zone4/temp: No data available
This error causes node_exporter to return no thermal data at all: in the loop which collects results, if any single stat returns an error, an empty slice is returned.
Temp used to be uint64 but is now int64. This means that returning a zero-value isn't a good way of signalling "no value".
There is existing optional handling of 'Mode' and 'Passive' attributes. In the case of 'Passive' it returns a *uint64 instead of uint64.
So the options I can see are:
-
Change
Tempfrom int64 to *int64. That obviously has knock-on effects on all consumers of this code. However such changes are not unknown - such as theuint64toint64change already mentioned, which was done ~2 weeks ago in de3a686. In fact, maybe now is a good time to do this.node_exporter in particular would need the corresponding change, but I don't know what the other main consumers of this library are.
-
Change the loop which collects thermal zones so that it silently drops a zone which generates ENODATA. No client changes required. Proof-of-concept:
--- a/vendor/github.com/prometheus/procfs/sysfs/class_thermal.go
+++ b/vendor/github.com/prometheus/procfs/sysfs/class_thermal.go
@@ -16,9 +16,11 @@
package sysfs
import (
+ "errors"
"os"
"path/filepath"
"strings"
+ "syscall"
"github.com/prometheus/procfs/internal/util"
)
@@ -43,16 +45,19 @@ func (fs FS) ClassThermalZoneStats() ([]ClassThermalZoneStats, error) {
}
var zoneStats = ClassThermalZoneStats{}
- stats := make([]ClassThermalZoneStats, len(zones))
- for i, zone := range zones {
+ stats := make([]ClassThermalZoneStats, 0, len(zones))
+ for _, zone := range zones {
zoneName := strings.TrimPrefix(filepath.Base(zone), "thermal_zone")
zoneStats, err = parseClassThermalZone(zone)
if err != nil {
+ if errors.Is(err, syscall.ENODATA) {
+ continue
+ }
return []ClassThermalZoneStats{}, err
}
zoneStats.Name = zoneName
- stats[i] = zoneStats
+ stats = append(stats, zoneStats)
}
return stats, nil
}
For my use case this is good enough, expecially since node_exporter ignores everything apart from Temp in struct ClassThermalZoneStats - here.