Add trains-init support for config file env override (as well as argument)

trains/config/default/__main__.py

@@ -1,18 +1,19 @@
+""" Trains configuration wizard"""
 from __future__ import print_function
 
+import argparse
 import os
 
-from six.moves import input
 from pathlib2 import Path
+from six.moves import input
 from six.moves.urllib.parse import urlparse
 
 from trains.backend_api.session import Session
 from trains.backend_api.session.defs import ENV_HOST
-from trains.backend_config.defs import LOCAL_CONFIG_FILES
+from trains.backend_config.defs import LOCAL_CONFIG_FILES, LOCAL_CONFIG_FILE_OVERRIDE_VAR
 from trains.config import config_obj
 from trains.utilities.pyhocon import ConfigFactory, ConfigMissingException
 
-
 description = """
 Please create new trains credentials through the profile page in your trains web app (e.g. http://localhost:8080/profile)
 In the profile page, press "Create new credentials", then press "Copy to clipboard".
@@ -25,14 +26,6 @@ try:
 except Exception:
     def_host = 'http://localhost:8080'
 
-host_description = """
-Editing configuration file: {CONFIG_FILE}
-Enter the url of the trains-server's Web service, for example: {HOST}
-""".format(
-    CONFIG_FILE=LOCAL_CONFIG_FILES[0],
-    HOST=def_host,
-)
-
 
 def get_user_input():
     """
@@ -64,9 +57,27 @@ def get_user_input():
             return os.linesep.join(input_list)
 
 
+def validate_file(string):
+    if not string:
+        raise argparse.ArgumentTypeError("expected a valid file path")
+    return string
+
+
 def main():
+    default_config_file = os.getenv(LOCAL_CONFIG_FILE_OVERRIDE_VAR) or LOCAL_CONFIG_FILES[0]
+
+    p = argparse.ArgumentParser(description=__doc__)
+    p.add_argument(
+        "--file", "-F", help="Target configuration file path (default is %(default)s)",
+        default=default_config_file,
+        type=validate_file
+    )
+
+    args = p.parse_args()
+
     print('TRAINS SDK setup process')
-    conf_file = Path(LOCAL_CONFIG_FILES[0]).absolute()
+
+    conf_file = Path(args.file).absolute()
     if conf_file.exists() and conf_file.is_file() and conf_file.stat().st_size > 0:
         print('Configuration file already exists: {}'.format(str(conf_file)))
         print('Leaving setup, feel free to edit the configuration file.')
@@ -96,6 +107,15 @@ def main():
 
     print('Detected credentials key=\"{}\" secret=\"{}\"'.format(credentials['access_key'],
                                                                  credentials['secret_key'][0:4] + "***"))
+
+    host_description = """
+    Editing configuration file: {CONFIG_FILE}
+    Enter the url of the trains-server's Web service, for example: {HOST}
+    """.format(
+        CONFIG_FILE=args.file,
+        HOST=def_host,
+    )
+
     if api_host:
         api_host = input_url('API Host', api_host)
     else:
@@ -265,8 +285,8 @@ def input_url(host_type, host=None):
 def input_host_port(host_type, parsed_host):
     print('Enter port for {} host '.format(host_type), end='')
     replace_port = input().lower()
-    return parsed_host.scheme + "://" + parsed_host.netloc + (':{}'.format(replace_port) if replace_port else '') + \
+    return (parsed_host.scheme + "://" + parsed_host.netloc + (':{}'.format(replace_port) if replace_port else '') +
-           parsed_host.path
+            parsed_host.path)
 
 
 def verify_url(parse_input):