prometheus/node_exporter · error

error obtaining sysctl info

Error message

error obtaining sysctl info: %w

What it means

newMetrics reads a numeric sysctl via c.fs.SysctlInts(s.name); any procfs read failure (missing file, permission, parse error) is wrapped as 'error obtaining sysctl info'. It is returned per-sysctl and surfaces in Update's error output, skipping that sysctl's metrics.

Solutions

1. Verify the sysctl exists: `sysctl <name>` or `cat /proc/sys/<path>`
2. Remove/adjust the include filter entry for sysctls absent on this kernel
3. Run the exporter with permission to read the file (or relax the file's perms)
4. Check procfs can parse it; if not, extend prometheus/procfs upstream

Example fix

// before
--collector.sysctl.include='vm.fake_stat'
// after
--collector.sysctl.include='vm.stat'

if _, err := os.Stat(filepath.Join("/proc/sys", strings.ReplaceAll(name, ".", "/"))); err != nil { /* skip this sysctl */ }

if err := coll.Update(ch); err != nil {
    if strings.Contains(err.Error(), "error obtaining sysctl info") {
        logger.Warn("sysctl unavailable on this kernel", "err", err)
    }
}

When it happens

Trigger: A configured --collector.sysctl --collector.sysctl.include=<name> references a sysctl that does not exist on this kernel, or exists but cannot be read as integers by procfs (permissions, or value not parseable as []int).

Common situations: Include list copied from another kernel version where the sysctl was renamed/removed; hardened kernels restricting /proc/sys reads to root; sysctl whose content procfs cannot parse.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• failed to open procfs
• failed to open procfs
• failed to open procfs
• failed to open procfs
• unable to retrieve limit number of threads

AI-assisted analysis of prometheus/node_exporter@17ddd77c59 (2026-09-07). Data as JSON: /api/errors/8af68fbdfd26ce1a. Report an issue: GitHub.

Appendix: source

Thrown at collector/sysctl_linux.go:97

		for _, metric := range metrics {
			ch <- metric
		}
	}
	return nil
}

func (c *sysctlCollector) newMetrics(s *sysctl) ([]prometheus.Metric, error) {
	var (
		values any
		length int
		err    error
	)

	if s.numeric {
		values, err = c.fs.SysctlInts(s.name)
		if err != nil {
			return nil, fmt.Errorf("error obtaining sysctl info: %w", err)
		}
		length = len(values.([]int))
	} else {
		values, err = c.fs.SysctlStrings(s.name)
		if err != nil {
			return nil, fmt.Errorf("error obtaining sysctl info: %w", err)
		}
		length = len(values.([]string))
	}

	switch length {
	case 0:
		return nil, fmt.Errorf("sysctl %s has no values", s.name)
	case 1:
		if len(s.keys) > 0 {
			return nil, fmt.Errorf("sysctl %s has only one value, but expected %v", s.name, s.keys)
		}
		return []prometheus.Metric{s.newConstMetric(values)}, nil

View on GitHub (pinned to 17ddd77c59)