feat(agent): /proc-based inventory collectors

agent/internal/inventory/collect_linux.go

@@ -0,0 +1,157 @@
+//go:build linux
+
+package inventory
+
+import (
+	"bufio"
+	"os"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/mrhid6/vantage/agent/internal/grpc/pb"
+)
+
+func collect(r *pb.InventoryReport, includeStatic bool) {
+	r.CPU.UsagePct = cpuUsage()
+	r.CPU.Load1 = load1()
+	memTotal, memAvail, swapTotal, swapFree := meminfo()
+	if memTotal > memAvail {
+		r.Memory.UsedBytes = memTotal - memAvail
+	}
+	if swapTotal > swapFree {
+		r.SwapUsed = swapTotal - swapFree
+	}
+	if includeStatic {
+		r.Memory.TotalBytes = memTotal
+		r.SwapTotal = swapTotal
+		r.CPU.Model, r.CPU.Cores = cpuStatic()
+		r.Kernel = kernel()
+		r.Partitions = partitions()
+	}
+}
+
+func readProc(path string) string { b, _ := os.ReadFile(path); return string(b) }
+
+func cpuSample() (idle, total uint64) {
+	f, err := os.Open("/proc/stat")
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	if sc.Scan() {
+		fields := strings.Fields(sc.Text()) // cpu user nice system idle iowait ...
+		for i, v := range fields[1:] {
+			n, _ := strconv.ParseUint(v, 10, 64)
+			total += n
+			if i == 3 { // idle
+				idle = n
+			}
+		}
+	}
+	return
+}
+
+func cpuUsage() float64 {
+	i1, t1 := cpuSample()
+	time.Sleep(100 * time.Millisecond)
+	i2, t2 := cpuSample()
+	dt := float64(t2 - t1)
+	if dt <= 0 {
+		return 0
+	}
+	return (1 - float64(i2-i1)/dt) * 100
+}
+
+func load1() float64 {
+	fields := strings.Fields(readProc("/proc/loadavg"))
+	if len(fields) > 0 {
+		v, _ := strconv.ParseFloat(fields[0], 64)
+		return v
+	}
+	return 0
+}
+
+func meminfo() (total, avail, swapTotal, swapFree uint64) {
+	f, err := os.Open("/proc/meminfo")
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		fields := strings.Fields(sc.Text())
+		if len(fields) < 2 {
+			continue
+		}
+		kb, _ := strconv.ParseUint(fields[1], 10, 64)
+		b := kb * 1024
+		switch strings.TrimSuffix(fields[0], ":") {
+		case "MemTotal":
+			total = b
+		case "MemAvailable":
+			avail = b
+		case "SwapTotal":
+			swapTotal = b
+		case "SwapFree":
+			swapFree = b
+		}
+	}
+	return
+}
+
+func cpuStatic() (model string, cores int) {
+	f, err := os.Open("/proc/cpuinfo")
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		line := sc.Text()
+		if strings.HasPrefix(line, "processor") {
+			cores++
+		} else if strings.HasPrefix(line, "model name") && model == "" {
+			if i := strings.Index(line, ":"); i >= 0 {
+				model = strings.TrimSpace(line[i+1:])
+			}
+		}
+	}
+	return
+}
+
+func kernel() string {
+	return strings.TrimSpace(readProc("/proc/sys/kernel/osrelease"))
+}
+
+func partitions() []pb.PartitionReport {
+	allowed := map[string]bool{"ext4": true, "xfs": true, "btrfs": true, "zfs": true, "vfat": true, "ntfs": true, "ext3": true}
+	f, err := os.Open("/proc/mounts")
+	if err != nil {
+		return nil
+	}
+	defer f.Close()
+	var out []pb.PartitionReport
+	seen := map[string]bool{}
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		fields := strings.Fields(sc.Text())
+		if len(fields) < 3 || !allowed[fields[2]] || seen[fields[1]] {
+			continue
+		}
+		seen[fields[1]] = true
+		var st syscall.Statfs_t
+		if syscall.Statfs(fields[1], &st) != nil {
+			continue
+		}
+		total := st.Blocks * uint64(st.Bsize)
+		free := st.Bavail * uint64(st.Bsize)
+		out = append(out, pb.PartitionReport{
+			Device: fields[0], Mountpoint: fields[1], Fstype: fields[2],
+			TotalBytes: total, UsedBytes: total - free,
+		})
+	}
+	return out
+}

agent/internal/inventory/collect_other.go

@@ -0,0 +1,8 @@
+//go:build !linux
+
+package inventory
+
+import "github.com/mrhid6/vantage/agent/internal/grpc/pb"
+
+// collect is a no-op best-effort stub on non-Linux platforms.
+func collect(r *pb.InventoryReport, includeStatic bool) {}

agent/internal/inventory/inventory.go

@@ -0,0 +1,11 @@
+package inventory
+
+import "github.com/mrhid6/vantage/agent/internal/grpc/pb"
+
+// Collect gathers metrics always and static hardware info when includeStatic.
+// Platform specifics are provided by collect_linux.go / collect_other.go.
+func Collect(includeStatic bool) *pb.InventoryReport {
+	r := &pb.InventoryReport{IncludeStatic: includeStatic, CPU: &pb.CPUReport{}, Memory: &pb.MemReport{}}
+	collect(r, includeStatic)
+	return r
+}