github.com/prometheus/procfs v0.22.0: FS.LoadAvg

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/github.com/prometheus/procfs@v0.22.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/prometheus/procfs@v0.22.0
Demonstrate these symbols/APIs:
  - procfs.FS.LoadAvg

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:c0c66d1c062cd0d9eec024accf7f5cb7d4931da3dcc5a4efd415850609702b3f","contract":["procfs.NewDefaultFS() returns (FS, error) where error is nil","fs.LoadAvg() returns (*LoadAvg, error) where error is nil and load values are non-negative","fs.LoadAvg() parses Load1, Load5, and Load15 metrics from procfs mount","procfs.FS.LoadAvg returns an error when reading from a proc mount missing loadavg"],"goal":"verify pkg:golang/github.com/prometheus/procfs@v0.22.0","kind":"HOW","packages":["pkg:golang/github.com/prometheus/procfs@v0.22.0"],"schemaVersion":1,"symbols":["procfs.FS.LoadAvg"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/prometheus/procfs@v0.22.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/prometheus/procfs@v0.22.0","symbols":["procfs.FS.LoadAvg"],"verifierAdapter":"golang@1"}

module example.com/sample

go 1.26.6

require github.com/prometheus/procfs v0.22.0

require golang.org/x/sys v0.47.0 // indirect

github.com/prometheus/procfs v0.22.0 h1:6q9+/JL9IKAPbCmBrv9n5O5Ty3NKnciV5X7YGw0oics=
github.com/prometheus/procfs v0.22.0/go.mod h1:CvmFr/GVhIjIvWJZW3tgkODBQMRIf0EyWMQLHCHab58=
golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=

package main

import (
	"fmt"
	"os"

	"github.com/prometheus/procfs"
)

// ReadLoadAvg returns current system load averages.
func ReadLoadAvg() (*procfs.LoadAvg, error) {
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		return nil, fmt.Errorf("procfs access failed: %w", err)
	}
	return fs.LoadAvg()
}

func main() {
	load, err := ReadLoadAvg()
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to read load averages: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Load averages: 1m=%.2f 5m=%.2f 15m=%.2f\n",
		load.Load1, load.Load5, load.Load15)
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/prometheus/procfs@v0.22.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/prometheus/procfs@v0.22.0"
  ],
  "symbols": [
    "procfs.FS.LoadAvg"
  ]
}

package main

import (
	"fmt"
	"os"
	"path/filepath"

	"github.com/prometheus/procfs"
)

func main() {
	// 1. Verify procfs.NewDefaultFS returns a valid FS instance
	fs, err := procfs.NewDefaultFS()
	if err != nil {
		fmt.Fprintf(os.Stderr, "procfs.NewDefaultFS failed: %v\n", err)
		os.Exit(1)
	}

	// 2. Verify fs.LoadAvg parses real /proc/loadavg
	loadAvg, err := fs.LoadAvg()
	if err != nil {
		fmt.Fprintf(os.Stderr, "fs.LoadAvg failed: %v\n", err)
		os.Exit(1)
	}
	if loadAvg.Load1 < 0 || loadAvg.Load5 < 0 || loadAvg.Load15 < 0 {
		fmt.Fprintf(os.Stderr, "expected non-negative load averages, got: %+v\n", loadAvg)
		os.Exit(1)
	}

	// 3. Verify fs.LoadAvg fails when loadavg file is missing
	tmpDir, err := os.MkdirTemp("", "proctest*")
	if err != nil {
		fmt.Fprintf(os.Stderr, "os.MkdirTemp failed: %v\n", err)
		os.Exit(1)
	}
	defer os.RemoveAll(tmpDir)

	mockFS, err := procfs.NewFS(tmpDir)
	if err != nil {
		fmt.Fprintf(os.Stderr, "procfs.NewFS failed: %v\n", err)
		os.Exit(1)
	}

	_, err = mockFS.LoadAvg()
	if err == nil {
		fmt.Fprintf(os.Stderr, "expected error when loadavg file is missing, got nil\n")
		os.Exit(1)
	}

	// 4. Verify mock loadavg parsing of Load1, Load5, and Load15
	mockContent := []byte("0.12 0.34 0.56 1/200 9999\n")
	if err := os.WriteFile(filepath.Join(tmpDir, "loadavg"), mockContent, 0644); err != nil {
		fmt.Fprintf(os.Stderr, "os.WriteFile failed: %v\n", err)
		os.Exit(1)
	}

	parsedLoad, err := mockFS.LoadAvg()
	if err != nil {
		fmt.Fprintf(os.Stderr, "mockFS.LoadAvg failed: %v\n", err)
		os.Exit(1)
	}
	if parsedLoad.Load1 != 0.12 || parsedLoad.Load5 != 0.34 || parsedLoad.Load15 != 0.56 {
		fmt.Fprintf(os.Stderr, "unexpected parsed values: %+v\n", parsedLoad)
		os.Exit(1)
	}

	fmt.Println("All contract assertions passed.")
}