[client] Prevent corruption from competing log rotation and improve debug bundle (#6214)

* Adds heuristic to detect an edge case on Linux where a system has configured logrotate as a separate service to rotate log files which would mangle our client log files. If we detect logrotate being configured for netbird, we disable our rotation.

* Adds new env var to disable log rotation: NB_LOG_DISABLE_ROTATION

* Adds compressed and plain logrotate files to debug bundle.

* Replaces lumberjack with timberjack (maintained fork with bug fixes and extra features).

* Clarifies which daemon version is running in the bundle stats.

* Change logging for client service status to console

util/log_test.go

@@ -0,0 +1,96 @@
+package util
+
+import (
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/require"
+)
+
+// TestSetupLogFile_RotatesOnSize drives >MaxSize bytes through the writer
+// returned by setupLogFile and asserts a backup file appears.
+func TestSetupLogFile_RotatesOnSize(t *testing.T) {
+	t.Setenv("NB_LOG_MAX_SIZE_MB", "1")
+
+	dir := t.TempDir()
+	logPath := filepath.Join(dir, "netbird.log")
+
+	w, err := setupLogFile(logPath, false)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		if c, ok := w.(io.Closer); ok {
+			_ = c.Close()
+		}
+	})
+
+	chunk := []byte(strings.Repeat("x", 64*1024) + "\n")
+	for range 20 {
+		_, err := w.Write(chunk)
+		require.NoError(t, err)
+	}
+
+	info, err := os.Stat(logPath)
+	require.NoError(t, err)
+	require.Less(t, info.Size(), int64(1<<20),
+		"active log should be < 1 MB after rotation, got %d", info.Size())
+
+	require.Eventually(t, func() bool {
+		entries, _ := os.ReadDir(dir)
+		for _, e := range entries {
+			name := e.Name()
+			if name == filepath.Base(logPath) {
+				continue
+			}
+			if strings.HasPrefix(name, "netbird-") && strings.HasSuffix(name, ".log.gz") {
+				return true
+			}
+		}
+		return false
+	}, 5*time.Second, 50*time.Millisecond, "expected a rotated backup file in %s", dir)
+}
+
+// TestSetupLogFile_RotationDisabled verifies that with rotation off, the file
+// grows past MaxSize and no backups are created.
+func TestSetupLogFile_RotationDisabled(t *testing.T) {
+	t.Setenv("NB_LOG_MAX_SIZE_MB", "1")
+
+	dir := t.TempDir()
+	logPath := filepath.Join(dir, "netbird.log")
+
+	w, err := setupLogFile(logPath, true)
+	require.NoError(t, err)
+
+	f, ok := w.(*os.File)
+	require.True(t, ok, "expected plain *os.File when rotation is disabled, got %T", w)
+	t.Cleanup(func() { _ = f.Close() })
+
+	chunk := []byte(strings.Repeat("y", 64*1024) + "\n")
+	for range 20 {
+		_, err := w.Write(chunk)
+		require.NoError(t, err)
+	}
+
+	info, err := os.Stat(logPath)
+	require.NoError(t, err)
+	require.GreaterOrEqual(t, info.Size(), int64(1<<20),
+		"file should exceed MaxSize when rotation is disabled, got %d", info.Size())
+
+	entries, err := os.ReadDir(dir)
+	require.NoError(t, err)
+	require.Len(t, entries, 1, "no backup files should exist when rotation is disabled, got %v", entries)
+}
+
+// TestIsRotationDisabled_EnvFlag covers the NB_LOG_DISABLE_ROTATION env path.
+// The logrotate-conflict branch is exercised separately on linux.
+func TestIsRotationDisabled_EnvFlag(t *testing.T) {
+	logger := log.New()
+	logger.SetOutput(io.Discard)
+
+	t.Setenv("NB_LOG_DISABLE_ROTATION", "true")
+	require.True(t, isRotationDisabled(logger))
+}