prometheus/node_exporter · error

failed to open procfs

Error message

failed to open procfs: %w

What it means

NewMeminfoCollector builds a procfs filesystem handle from the --path.procfs flag (default /proc) via procfs.NewFS. If procfs cannot be mounted/opened at that path, the collector cannot be constructed and this wrapped error is returned at startup. It almost always means the procfs mount point is missing, not mounted, or the configured path is wrong.

Solutions

1. Ensure /proc is mounted in the container/environment (docker run without disabling /proc, or explicitly mount it: -v /proc:/proc:ro)
2. Verify the --path.procfs flag points to a mounted procfs directory (check with `ls <path>/meminfo`)
3. If running in a restrictive sandbox, run the collector with the privileges/namespace access needed to read /proc
4. Disable the meminfo collector (e.g. build with the nomeminfo tag or --collector.meminfo flag off) if /proc is intentionally unavailable

Example fix

// before (container start)
docker run --rm my-node-exporter
// after
docker run --rm -v /proc:/host/proc:ro my-node-exporter --path.procfs=/host/proc

const procPath = "/proc"
if info, err := os.Stat(filepath.Join(procPath, "meminfo")); err != nil || info.IsDir() {
    log.Fatalf("procfs not available at %s: %v", procPath, err)
}

collector, err := NewMeminfoCollector(logger)
if err != nil {
    logger.Error("failed to init meminfo collector; is /proc mounted?", "err", err)
    return err
}

When it happens

Trigger: procfs.NewFS(*procPath) returns an error because the directory given by --path.procfs does not exist, is not a directory, is unreadable, or /proc is not mounted — typically in containers without /proc mounted or with a custom --path.procfs value pointing at a nonexistent location.

Common situations: Running node_exporter in a Docker/container runtime where /proc was not bind-mounted; running in a chroot or minimal image lacking /proc; typo in --path.procfs; running inside restricted namespaces (e.g. some CI sandboxes) where procfs is hidden.

Understand the failure class

Background: "open() failed", "failed to open file", "cannot create file" — what a file open error means and how to fix it — this error's family across 42 libraries.

Related errors

• failed to open procfs
• failed to open procfs
• failed to open procfs
• failed to open sysfs
• failed to open sysfs

AI-assisted analysis of prometheus/node_exporter@17ddd77c59 (2026-09-07). Data as JSON: /api/errors/218250c54d3ab185. Report an issue: GitHub.

Appendix: source

Thrown at collector/meminfo_linux.go:34

package collector

import (
	"fmt"
	"log/slog"

	"github.com/prometheus/procfs"
)

type meminfoCollector struct {
	fs     procfs.FS
	logger *slog.Logger
}

// NewMeminfoCollector returns a new Collector exposing memory stats.
func NewMeminfoCollector(logger *slog.Logger) (Collector, error) {
	fs, err := procfs.NewFS(*procPath)
	if err != nil {
		return nil, fmt.Errorf("failed to open procfs: %w", err)
	}

	return &meminfoCollector{
		logger: logger,
		fs:     fs,
	}, nil
}

func (c *meminfoCollector) getMemInfo() (map[string]float64, error) {
	meminfo, err := c.fs.Meminfo()
	if err != nil {
		return nil, fmt.Errorf("failed to get memory info: %w", err)
	}

	metrics := make(map[string]float64)

	if meminfo.ActiveBytes != nil {
		metrics["Active_bytes"] = float64(*meminfo.ActiveBytes)

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