From 32514c8f4f46e0f2156df80897c97e437335f483 Mon Sep 17 00:00:00 2001
From: Ryan Fairfax <rfairfax@linux.microsoft.com>
Date: Wed, 23 Feb 2022 02:02:01 +0100
Subject: [PATCH] shell: Add option to keep current environment

When doing interactive development via kas shell it is often desirable
to keep the user's customized configuration. The new --preserve-env
argument has been added to support this scenario via an opt in flag.

This flag is blocked  when not running from a TTY or via kas-container
and kas issues a warning to the user about potential unintended side
effects when invoked.

Signed-off-by: Ryan Fairfax <rfairfax@linux.microsoft.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 kas-container        |  4 ++++
 kas/libcmds.py       |  8 ++++++++
 kas/plugins/shell.py | 25 ++++++++++++++++++++++++-
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/kas-container b/kas-container
index dff106b..094a89b 100755
--- a/kas-container
+++ b/kas-container
@@ -289,6 +289,10 @@ while [ $# -gt 0 ] && [ $KAS_EXTRA_BITBAKE_ARGS -eq 0 ]; do
 		KAS_BITBAKE_C_OPTION_ARGS="$2"
 		shift 2
 		;;
+	-E|--preserve-env)
+		echo "$1 is not supported with kas-container"
+		exit 1
+		;;
 	--)
 		KAS_EXTRA_BITBAKE_ARGS=$#
 		;;
diff --git a/kas/libcmds.py b/kas/libcmds.py
index 35668fc..4a646f3 100644
--- a/kas/libcmds.py
+++ b/kas/libcmds.py
@@ -148,6 +148,14 @@ class SetupHome(Command):
         Sets up the home directory of kas.
     """
 
+    # A list of environment variables that SETUP_HOME uses
+    # This should be kept up to date with any code in execute()
+    ENV_VARS = [
+        'GIT_CREDENTIAL_HELPER',
+        'AWS_CONFIG_FILE',
+        'AWS_SHARED_CREDENTIALS_FILE',
+    ]
+
     def __init__(self):
         super().__init__()
         self.tmpdirname = tempfile.mkdtemp()
diff --git a/kas/plugins/shell.py b/kas/plugins/shell.py
index 2299618..5564da2 100644
--- a/kas/plugins/shell.py
+++ b/kas/plugins/shell.py
@@ -38,11 +38,12 @@
 """
 
 import logging
+import os
 import subprocess
 import sys
 from kas.context import create_global_context
 from kas.config import Config
-from kas.libcmds import Macro, Command
+from kas.libcmds import Macro, Command, SetupHome
 from kas.libkas import setup_parser_common_args
 
 __license__ = 'MIT'
@@ -70,6 +71,9 @@ class Shell:
         parser.add_argument('-c', '--command',
                             help='Run command',
                             default='')
+        parser.add_argument('-E', '--preserve-env',
+                            help='Keep current user enviornment block',
+                            action='store_true')
 
     def run(self, args):
         """
@@ -79,6 +83,25 @@ class Shell:
         ctx = create_global_context(args)
         ctx.config = Config(ctx, args.config)
 
+        if args.preserve_env:
+            # Warn if there's any settings that setup_home would apply
+            # but are now ignored
+            for var in SetupHome.ENV_VARS:
+                if var in os.environ:
+                    logging.warning('Environment variable "%s" ignored '
+                                    'because user environment is being used',
+                                    var)
+
+            if not os.isatty(sys.stdout.fileno()):
+                logging.error("Error: --preserve-env can only be "
+                              "run from a tty")
+                sys.exit(1)
+
+            ctx.environ = os.environ.copy()
+
+            logging.warning("Preserving the current environment block may "
+                            "have unintended side effects on the build.")
+
         if args.keep_config_unchanged:
             # Skip the tasks which would change the config of the build
             # environment