feat: initial commit

internal/agent/update.go

@@ -0,0 +1,76 @@
+package agent
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"time"
+
+	"github.com/x-grk/longpolling-remote-access/internal/proto"
+)
+
+// doUpdate downloads the latest agent binary for this platform, atomically
+// replaces the running executable, and schedules a service restart. It never
+// uninstalls — only updates.
+func (a *Agent) doUpdate() proto.TaskResult {
+	exe, err := os.Executable()
+	if err != nil {
+		return proto.TaskResult{Error: "не удалось определить путь бинарника: " + err.Error()}
+	}
+	exe, _ = filepath.EvalSymlinks(exe)
+
+	url := fmt.Sprintf("%s/download/agent-%s-%s", a.cfg.Host, runtime.GOOS, runtime.GOARCH)
+	req, _ := http.NewRequestWithContext(context.Background(), http.MethodGet, url, nil)
+	resp, err := a.http.Do(req)
+	if err != nil {
+		return proto.TaskResult{Error: "скачивание: " + err.Error()}
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return proto.TaskResult{Error: "скачивание: сервер вернул " + resp.Status}
+	}
+
+	tmp := exe + ".new"
+	f, err := os.OpenFile(tmp, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o755)
+	if err != nil {
+		return proto.TaskResult{Error: "создание файла: " + err.Error()}
+	}
+	if _, err := io.Copy(f, resp.Body); err != nil {
+		f.Close()
+		os.Remove(tmp)
+		return proto.TaskResult{Error: "запись: " + err.Error()}
+	}
+	f.Close()
+
+	// Atomic replace: renaming over a running executable is allowed on Linux;
+	// the live process keeps the old inode until it restarts.
+	if err := os.Rename(tmp, exe); err != nil {
+		os.Remove(tmp)
+		return proto.TaskResult{Error: "замена бинарника: " + err.Error()}
+	}
+
+	// Restart shortly, after the result has been reported.
+	go func() {
+		time.Sleep(1500 * time.Millisecond)
+		restartSelf()
+	}()
+
+	data, _ := json.Marshal(map[string]string{"status": "обновлено, перезапуск"})
+	return proto.TaskResult{OK: true, Data: data}
+}
+
+// restartSelf restarts the agent so the new binary takes effect.
+func restartSelf() {
+	if path, err := exec.LookPath("systemctl"); err == nil {
+		_ = exec.Command(path, "restart", "lpagent").Start()
+		return
+	}
+	// No systemd (e.g. launchd/manual run): exit so the supervisor restarts us.
+	os.Exit(0)
+}