Add centralized constants module and .env configuration support

app/utils.py

@@ -16,6 +16,8 @@ from __future__ import annotations
 
 import argparse
 
+from .constants import DEFAULT_TOP
+
 
 def arg_parser(description: str, default_log_path: str,
                default_report_dir: str) -> argparse.ArgumentParser:
@@ -24,8 +26,8 @@ def arg_parser(description: str, default_log_path: str,
                    help=f"log directory (default: {default_log_path})")
     p.add_argument("--report-dir", default=default_report_dir,
                    help=f"report output dir (default: {default_report_dir})")
-    p.add_argument("--top", type=int, default=30,
-                   help="rows in the top-IP table (default: 30)")
+    p.add_argument("--top", type=int, default=DEFAULT_TOP,
+                   help=f"rows in the top-IP table (default: {DEFAULT_TOP})")
     p.add_argument("--quiet", action="store_true",
                    help="write files, print nothing but the paths")
     p.add_argument("--no-rsc", action="store_true",