v0.2.0 (#50)

Co-authored-by: Tasnim Kabir Sadik <tksadik@omukk.dev>

Reviewed-on: wrenn/wrenn#50

internal/vm/cleanup.go

@@ -0,0 +1,104 @@
+package vm
+
+import (
+	"log/slog"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// CleanupStaleProcesses kills any cloud-hypervisor processes left behind by a
+// previous agent that crashed without graceful shutdown. Must run at agent
+// startup before devicemapper.CleanupStaleDevices — a still-running CH process
+// holds the dm-snapshot open and would cause "Device or resource busy" on
+// dmsetup remove.
+//
+// Matches processes by argv containing the wrenn CH API socket path
+// (/tmp/ch-<sandboxID>.sock) so we don't kill unrelated cloud-hypervisor VMs
+// the operator may be running.
+//
+// Also removes stale /tmp/ch-*.sock files once the owning process is gone.
+func CleanupStaleProcesses() {
+	socketPattern := regexp.MustCompile(`/tmp/ch-[A-Za-z0-9-]+\.sock`)
+
+	pids, err := scanProcs()
+	if err != nil {
+		slog.Debug("scan procs failed", "error", err)
+		return
+	}
+
+	killed := 0
+	for _, pid := range pids {
+		cmdline, err := readCmdline(pid)
+		if err != nil {
+			continue
+		}
+		if !strings.Contains(cmdline, "cloud-hypervisor") {
+			continue
+		}
+		if !socketPattern.MatchString(cmdline) {
+			continue
+		}
+		slog.Warn("killing stale cloud-hypervisor process", "pid", pid, "cmdline", cmdline)
+		if err := syscall.Kill(pid, syscall.SIGTERM); err != nil {
+			slog.Warn("SIGTERM stale CH failed", "pid", pid, "error", err)
+		}
+		killed++
+	}
+
+	// Give SIGTERM'd processes a brief window to exit so subsequent dm/loop
+	// teardown sees no open fd, then SIGKILL anything still alive.
+	if killed > 0 {
+		time.Sleep(500 * time.Millisecond)
+		for _, pid := range pids {
+			cmdline, err := readCmdline(pid)
+			if err != nil {
+				continue
+			}
+			if !strings.Contains(cmdline, "cloud-hypervisor") || !socketPattern.MatchString(cmdline) {
+				continue
+			}
+			_ = syscall.Kill(pid, syscall.SIGKILL)
+		}
+		time.Sleep(200 * time.Millisecond)
+	}
+
+	matches, _ := filepath.Glob("/tmp/ch-*.sock")
+	for _, sock := range matches {
+		if err := os.Remove(sock); err == nil {
+			slog.Info("removed stale CH socket", "path", sock)
+		}
+	}
+}
+
+func scanProcs() ([]int, error) {
+	entries, err := os.ReadDir("/proc")
+	if err != nil {
+		return nil, err
+	}
+	var pids []int
+	for _, e := range entries {
+		if !e.IsDir() {
+			continue
+		}
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		pids = append(pids, pid)
+	}
+	return pids, nil
+}
+
+func readCmdline(pid int) (string, error) {
+	b, err := os.ReadFile("/proc/" + strconv.Itoa(pid) + "/cmdline")
+	if err != nil {
+		return "", err
+	}
+	// /proc/<pid>/cmdline is NUL-separated; convert to spaces for substring match.
+	return strings.ReplaceAll(string(b), "\x00", " "), nil
+}