help epilog with env var for api token

README.md

@@ -143,6 +143,8 @@ usage: nrx [-h] [-v] [-d] [-I [VERSION]] [-c CONFIG] [-i INPUT] [-o OUTPUT] [-a
 
 nrx - network topology exporter by netreplica
 
+online documentation: https://github.com/netreplica/nrx/blob/main/README.md
+
 optional arguments:
   -h, --help                show this help message and exit
   -v, --version             show version number and exit
@@ -162,6 +164,9 @@ optional arguments:
   -T, --templates TEMPLATES directory with template files, will be prepended to TEMPLATES_PATH list in the configuration file
   -M, --map MAP             file with platform mappings to node parameters (default: platform_map.yaml in templates folder)
   -D, --dir DIR             save files into directory DIR (topology name is used by default). nested relative and absolute paths are OK
+
+To pass authentication token, use configuration file or environment variable:
+export NB_API_TOKEN='replace_with_valid_API_token'
 ```
 
 Note: for security reasons, there is no argument to pass an API token. Use either an environmental variable or a configuration file.

src/nrx/nrx.py

@@ -26,14 +26,17 @@
 
 It can also read the topology graph previously saved as a CYJS file to convert it into the one of supported network emulation formats.
 """
-
+# Standard library imports
 import os
 import sys
 import argparse
+from argparse import RawDescriptionHelpFormatter
 import json
 import math
 import ast
+import textwrap
 import zipfile
+# Third-party library imports
 import toml
 import pynetbox
 import requests
@@ -43,7 +46,6 @@
 import networkx as nx
 import jinja2
 import yaml
-import textwrap
 
 # Single source version
 from nrx.__about__ import __version__
@@ -984,14 +986,15 @@ def arg_input_check(s):
 
 def parse_args():
     """CLI arguments parser"""
-    from argparse import RawDescriptionHelpFormatter
     args_parser = argparse.ArgumentParser(prog='nrx',
                                           formatter_class=RawDescriptionHelpFormatter,
                                           description=textwrap.dedent("""
-                                                nrx - network topology exporter by netreplica
+                                            nrx - network topology exporter by netreplica
 
-                                                online documentation: https://github.com/netreplica/nrx/blob/main/README.md
-                                          """))
+                                            online documentation: https://github.com/netreplica/nrx/blob/main/README.md"""),
+                                          epilog=textwrap.dedent("""
+                                            To pass authentication token, use configuration file or environment variable:
+                                            export NB_API_TOKEN='replace_with_valid_API_token'"""))
 
     sites_group = args_parser.add_mutually_exclusive_group()