H2T (Host-to-target) installs and prevent host pollution (#3978)

* Add host-to-target (H2T) installation mode detection

- Add running_from_host() function to detect if running from installed system vs ISO
- Function checks for /run/archiso existence (ISO mode) vs host mode
- Add clear logging of installation mode on startup
- Skip keyboard layout changes when running from host system
- Fix Pyright type error in jsonify() by using Any instead of object
- Update README to mention installation from existing system

This enables archinstall to be run from an existing Arch installation
to perform host-to-target installs on other disks/partitions.

* match existing style

* rem debug

* info -> debug

README.md

@@ -6,7 +6,7 @@
 [![Lint Python and Find Syntax Errors](https://github.com/archlinux/archinstall/actions/workflows/flake8.yaml/badge.svg)](https://github.com/archlinux/archinstall/actions/workflows/flake8.yaml)
 
 Just another guided/automated [Arch Linux](https://wiki.archlinux.org/index.php/Arch_Linux) installer with a twist.
-The installer also doubles as a python library to install Arch Linux and manage services, packages, and other things inside the installed system *(Usually from a live medium)*.
+The installer also doubles as a python library to install Arch Linux and manage services, packages, and other things inside the installed system *(Usually from a live medium or from an existing installation)*.
 
 * archinstall [discord](https://discord.gg/aDeMffrxNg) server
 * archinstall [#archinstall:matrix.org](https://matrix.to/#/#archinstall:matrix.org) Matrix channel

archinstall/__init__.py

@@ -13,6 +13,7 @@ from archinstall.lib.networking import ping
 from archinstall.lib.packages.packages import check_package_upgrade
 from archinstall.tui.ui.components import tui as ttui
 
+from .lib.general import running_from_host
 from .lib.hardware import SysInfo
 from .lib.output import FormattedOutput, debug, error, info, log, warn
 from .lib.pacman import Pacman
@@ -110,6 +111,12 @@ def main() -> int:
 				info(new_version)
 				time.sleep(3)
 
+	if running_from_host():
+		# log which mode we are using
+		debug('Running from Host (H2T Mode)...')
+	else:
+		debug('Running from ISO (Live Mode)...')
+
 	script = arch_config_handler.get_script()
 
 	mod_name = f'archinstall.scripts.{script}'

archinstall/lib/general.py

@@ -27,6 +27,17 @@ _VT100_ESCAPE_REGEX = r'\x1B\[[?0-9;]*[a-zA-Z]'
 _VT100_ESCAPE_REGEX_BYTES = _VT100_ESCAPE_REGEX.encode()
 
 
+def running_from_host() -> bool:
+	"""
+	Check if running from an installed system.
+
+	Returns True if running from installed system (host mode) for host-to-target install.
+	Returns False if /run/archiso exists (ISO mode).
+	"""
+	is_host = not Path('/run/archiso').exists()
+	return is_host
+
+
 def generate_password(length: int = 64) -> str:
 	haystack = string.printable  # digits, ascii_letters, punctuation (!"#$[] etc) and whitespace
 	return ''.join(secrets.choice(haystack) for _ in range(length))
@@ -46,7 +57,7 @@ def clear_vt100_escape_codes_from_str(data: str) -> str:
 	return re.sub(_VT100_ESCAPE_REGEX, '', data)
 
 
-def jsonify(obj: object, safe: bool = True) -> object:
+def jsonify(obj: Any, safe: bool = True) -> Any:
 	"""
 	Converts objects into json.dumps() compatible nested dictionaries.
 	Setting safe to True skips dictionary keys starting with a bang (!)
@@ -84,7 +95,7 @@ class JSON(json.JSONEncoder, json.JSONDecoder):
 	"""
 
 	@override
-	def encode(self, o: object) -> str:
+	def encode(self, o: Any) -> str:
 		return super().encode(jsonify(o))
 
 
@@ -94,7 +105,7 @@ class UNSAFE_JSON(json.JSONEncoder, json.JSONDecoder):
 	"""
 
 	@override
-	def encode(self, o: object) -> str:
+	def encode(self, o: Any) -> str:
 		return super().encode(jsonify(o, safe=False))
 
 

archinstall/lib/locale/utils.py

@@ -1,5 +1,5 @@
 from ..exceptions import ServiceException, SysCallError
-from ..general import SysCommand
+from ..general import SysCommand, running_from_host
 from ..output import error
 
 
@@ -79,6 +79,11 @@ def get_kb_layout() -> str:
 
 
 def set_kb_layout(locale: str) -> bool:
+	if running_from_host():
+		# Skip when running from host - no need to change host keymap
+		# The target installation keymap is set via installer.set_keyboard_language()
+		return True
+
 	if len(locale.strip()):
 		if not verify_keyboard_layout(locale):
 			error(f'Invalid keyboard locale specified: {locale}')