feat: assemble an installable Gentoo live image in an exported rootfs
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Codex
+296
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"""Prepare only exported Gentoo payloads and configure the dedicated guest network."""
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import argparse
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import hashlib
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import ipaddress
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import json
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import os
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from pathlib import Path
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import re
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import shutil
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import subprocess
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import sys
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LABEL = 'HYDRA_OS'
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BRIDGE = 'hydrabr0'
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SUBNET = ipaddress.ip_network('10.203.0.0/24')
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CONNECTION_UUID = 'c84844bd-2955-4a61-9463-5e540140f9a2'
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class ImageError(RuntimeError):
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pass
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def root_path(root, relative, follow_leaf=True):
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root = Path(root).resolve()
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if root == Path('/') or not root.is_dir():
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raise ImageError('Expected an isolated exported rootfs directory')
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relative = Path(relative)
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if relative.is_absolute() or '..' in relative.parts:
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raise ImageError('Payload path must be relative and remain inside the export')
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path = root / relative
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checked = path if follow_leaf else path.parent
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if not checked.resolve().is_relative_to(root):
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raise ImageError(f'Payload symlink escapes the export: {relative}')
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return path
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def remove(root, relative):
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path = root_path(root, relative, follow_leaf=False)
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if path.is_symlink() or path.is_file():
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path.unlink()
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elif path.is_dir():
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shutil.rmtree(path)
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def write(root, relative, content, mode=0o644):
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path = root_path(root, relative)
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path.parent.mkdir(parents=True, exist_ok=True)
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path.write_text(content)
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path.chmod(mode)
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return path
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def sanitize_rootfs(root):
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"""Erase builder identity/secrets in the exported copy, retaining Gentoo updates."""
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for relative in ('etc/portage/gnupg', 'etc/portage/gnupg.hydra-untrusted',
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'var/lib/hydra-build', 'root', 'home', 'var/cache', 'var/tmp',
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'tmp', 'run', 'var/log', 'var/lib/systemd/random-seed',
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'var/lib/NetworkManager', 'etc/NetworkManager/system-connections',
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'hydra-source', 'hydra-cache', 'hydra-output'):
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remove(root, relative)
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for name in root_path(root, 'etc/ssh').glob('ssh_host_*'):
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remove(root, str(name.relative_to(root)))
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for relative, mode in [('root', 0o700), ('home', 0o755), ('tmp', 0o1777),
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('var/tmp', 0o1777), ('run', 0o755), ('var/log', 0o755),
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('var/cache', 0o755), ('dev', 0o755), ('proc', 0o755), ('sys', 0o755)]:
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path = root_path(root, relative)
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path.mkdir(parents=True, exist_ok=True)
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path.chmod(mode)
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remove(root, 'etc/machine-id')
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write(root, 'etc/machine-id', '')
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remove(root, 'var/lib/dbus/machine-id')
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path = root_path(root, 'var/lib/dbus/machine-id', follow_leaf=False)
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path.parent.mkdir(parents=True, exist_ok=True)
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path.symlink_to('/etc/machine-id')
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write(root, 'etc/hostname', 'hydra-os\n')
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write(root, 'etc/hosts', '127.0.0.1 localhost\n::1 localhost\n127.0.1.1 hydra-os\n')
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remove(root, 'etc/resolv.conf')
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root_path(root, 'etc/resolv.conf', follow_leaf=False).symlink_to('/run/NetworkManager/resolv.conf')
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def copy_overlay(root, overlay):
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for source in sorted(Path(overlay).rglob('*')):
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destination = root_path(root, source.relative_to(overlay))
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if source.is_symlink():
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raise ImageError('Source overlay must contain ordinary directories/files')
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if source.is_dir():
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destination.mkdir(parents=True, exist_ok=True)
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elif source.is_file():
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destination.parent.mkdir(parents=True, exist_ok=True)
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shutil.copyfile(source, destination)
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destination.chmod(source.stat().st_mode & 0o777)
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def kernel_version(root):
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modules = root_path(root, 'lib/modules')
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versions = sorted(path.name for path in modules.iterdir() if path.is_dir()) if modules.is_dir() else []
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if len(versions) != 1 or not re.fullmatch(r'[A-Za-z0-9_.+-]+', versions[0]):
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raise ImageError('Exactly one installed payload kernel is required')
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if not root_path(root, 'boot/vmlinuz-' + versions[0]).is_file():
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raise ImageError('Installed modules have no matching /boot/vmlinuz-VERSION')
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return versions[0]
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def live_kernel_args():
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return [f'root=live:CDLABEL={LABEL}', 'rd.live.image', 'rd.live.overlay.overlayfs=1',
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'ro', 'console=tty0', 'console=ttyS0,115200n8']
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def source_files(source):
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source = Path(source)
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result = {}
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for directory in ('image', 'hydra', 'bin', 'session', 'patches'):
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for path in sorted((source / directory).rglob('*')):
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if path.is_file() and '__pycache__' not in path.parts and path.suffix != '.pyc':
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result[str(path.relative_to(source))] = digest(path)
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return result
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def source_identity(source):
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return hashlib.sha256(json.dumps(source_files(source), sort_keys=True).encode()).hexdigest()
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def payload_manifest(root, source):
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packages = []
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database = root_path(root, 'var/db/pkg')
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for use in sorted(database.glob('*/*/USE')):
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package = use.parent
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built = package / 'BUILD_TIME'
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packages.append({'package': str(package.relative_to(database)), 'use': use.read_text().split(),
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'build_time': built.read_text().strip() if built.is_file() else None})
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commit = os.environ.get('HYDRA_SOURCE_COMMIT')
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if not commit:
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git = subprocess.run(['git', '-C', str(source), 'rev-parse', 'HEAD'], text=True, capture_output=True)
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commit = git.stdout.strip() if git.returncode == 0 else None
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return {'format': 1, 'label': LABEL, 'kernel': kernel_version(root),
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'live_kernel_args': live_kernel_args(), 'source_commit': commit,
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'source_files': source_files(source), 'sources': json.loads((Path(source) / 'image/sources.json').read_text()),
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'packages': packages}
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def artifacts_valid(directory, state):
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artifacts = state.get('artifacts')
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if not isinstance(artifacts, dict) or not artifacts:
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return False
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for name, expected in artifacts.items():
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if not isinstance(name, str) or Path(name).name != name or not isinstance(expected, str):
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return False
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path = Path(directory) / name
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try:
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if path.is_symlink() or not path.is_file() or digest(path) != expected:
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return False
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except OSError:
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return False
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return True
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def configure_rootfs(root, source):
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root, source = Path(root), Path(source)
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# Refuse incomplete integrations before changing the exported copy.
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for name in ('bin/hydra', 'bin/hydra-install', 'hydra/session.py', 'hydra/installer.py'):
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if not (source / name).is_file():
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raise ImageError(f'Required committed runtime/installer asset is missing: {name}')
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version = kernel_version(root)
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sanitize_rootfs(root)
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copy_overlay(root, source / 'image/rootfs')
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write(root, 'etc/hydra/live-mode/dracut.conf', (source / 'image/dracut.conf').read_text())
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root_path(root, 'etc/hydra/live-mode/dracut.conf.d').mkdir()
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package = root_path(root, 'usr/lib/hydra/hydra')
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package.mkdir(parents=True, exist_ok=True)
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for module in sorted((source / 'hydra').glob('*.py')):
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shutil.copyfile(module, root_path(root, 'usr/lib/hydra/hydra/' + module.name))
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for name, module in (('hydra', 'cli'), ('hydra-install', 'installer')):
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write(root, 'usr/bin/' + name,
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'#!/usr/bin/python3\nimport sys\nsys.path.insert(0, "/usr/lib/hydra")\n'
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f'from hydra.{module} import main\nraise SystemExit(main())\n', 0o755)
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write(root, 'usr/bin/hydra-session', '#!/bin/sh\nexec /usr/bin/hydra session "$@"\n', 0o755)
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write(root, 'usr/bin/hydra-network', '#!/usr/bin/python3\nimport sys\nsys.path.insert(0, "/usr/lib/hydra")\n'
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'from hydra.image import network_main\nraise SystemExit(network_main())\n', 0o755)
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write(root, 'usr/share/hydra/build-manifest.json', json.dumps(payload_manifest(root, source), indent=2) + '\n')
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make = root_path(root, 'etc/portage/make.conf')
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if make.is_file():
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settings = make.read_text()
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settings = re.sub(r'(?<=[\s"\'])-(?:usersandbox|sandbox|network-sandbox|ipc-sandbox|pid-sandbox)(?=[\s"\']|$)', '', settings)
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make.write_text(settings)
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for path in root_path(root, 'etc/sudoers.d').iterdir():
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path.chmod(0o440)
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return version
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def check_network_conflicts(routes, addresses):
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try:
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if not isinstance(routes, list) or not isinstance(addresses, list):
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raise ValueError('Expected JSON arrays')
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for route in routes:
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dst = route.get('dst')
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if dst in ('default', None):
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continue
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network = ipaddress.ip_network(dst, strict=False)
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if network.version != 4:
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raise ValueError('Unexpected non-IPv4 route')
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if network.overlaps(SUBNET) and not (route.get('dev') == BRIDGE and network.subnet_of(SUBNET)):
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raise ImageError(f'Guest subnet {SUBNET} conflicts with route {dst} on {route.get("dev")}')
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for interface in addresses:
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for addr in interface['addr_info']:
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if addr.get('family') != 'inet':
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continue
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network = ipaddress.ip_network(f'{addr["local"]}/{addr["prefixlen"]}', strict=False)
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owned = interface['ifname'] == BRIDGE and addr['local'] == '10.203.0.1' and addr['prefixlen'] == 24
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if network.overlaps(SUBNET) and not owned:
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raise ImageError(f'Guest subnet {SUBNET} conflicts with address on {interface["ifname"]}')
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except (ValueError, KeyError, TypeError, AttributeError) as error:
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raise ImageError('Cannot safely interpret IPv4 routes/addresses') from error
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def configure_network(run=subprocess.run):
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def command(argv, **kwargs):
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result = run(argv, text=True, capture_output=True, **kwargs)
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if result.returncode:
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raise ImageError(f'Network command failed: {argv[0]}: {result.stderr.strip()}')
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return result.stdout
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routes = json.loads(command(['ip', '-json', '-4', 'route', 'show', 'table', 'all']))
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addresses = json.loads(command(['ip', '-json', '-4', 'address', 'show']))
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check_network_conflicts(routes, addresses)
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probe = run(['nmcli', '--get-values', 'connection.uuid,connection.type,connection.interface-name,ipv4.method,ipv4.addresses',
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'connection', 'show', 'uuid', CONNECTION_UUID], text=True, capture_output=True)
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exists = probe.returncode == 0
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if exists and probe.stdout.strip().splitlines() != [CONNECTION_UUID, 'bridge', BRIDGE, 'manual', '10.203.0.1/24']:
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raise ImageError('Hydra bridge connection exists with unexpected configuration')
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if not exists and probe.returncode != 10:
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raise ImageError('Cannot query NetworkManager connections')
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links = json.loads(command(['ip', '-json', '-details', 'link', 'show']))
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for link in links:
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if link.get('ifname') == BRIDGE and (not exists or link.get('linkinfo', {}).get('info_kind') != 'bridge'):
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raise ImageError('Refusing to replace an existing interface named hydrabr0')
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if not exists:
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command(['nmcli', 'connection', 'add', 'type', 'bridge', 'con-name', 'hydra-guest',
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'ifname', BRIDGE, 'connection.uuid', CONNECTION_UUID,
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'connection.autoconnect', 'no', 'bridge.stp', 'no',
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'ipv4.method', 'manual', 'ipv4.addresses', '10.203.0.1/24',
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'ipv4.never-default', 'yes', 'ipv6.method', 'disabled'])
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# Activation is always gated by the fresh route/address check, including restarts.
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command(['nmcli', 'connection', 'up', 'uuid', CONNECTION_UUID])
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command(['sysctl', '-w', 'net.ipv4.ip_forward=1'])
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table = run(['nft', 'list', 'table', 'ip', 'hydra_nat'], text=True, capture_output=True)
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rules = ('delete table ip hydra_nat\n' if table.returncode == 0 else '') + '''table ip hydra_nat {
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chain postrouting {
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type nat hook postrouting priority srcnat; policy accept;
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ip saddr 10.203.0.0/24 oifname != "hydrabr0" masquerade
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}
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}
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'''
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command(['nft', '-f', '-'], input=rules)
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def network_main():
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try:
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configure_network()
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except (ImageError, OSError, ValueError) as error:
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print(f'hydra-network: {error}', file=sys.stderr)
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return 1
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return 0
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def digest(path):
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value = hashlib.sha256()
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with Path(path).open('rb') as stream:
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for block in iter(lambda: stream.read(1024 * 1024), b''):
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value.update(block)
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return value.hexdigest()
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def main(argv=None):
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parser = argparse.ArgumentParser(description=__doc__)
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parser.add_argument('step', choices=('configure', 'kernel', 'network'))
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parser.add_argument('root', nargs='?', type=Path)
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parser.add_argument('--source', type=Path)
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options = parser.parse_args(argv)
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try:
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if options.step == 'network':
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return network_main()
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if options.root is None:
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raise ImageError('An isolated rootfs directory is required')
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if options.step == 'kernel':
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print(kernel_version(options.root))
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else:
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if options.source is None:
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raise ImageError('Source checkout is required')
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configure_rootfs(options.root, options.source)
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except (ImageError, OSError, ValueError) as error:
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print(f'hydra-image: {error}', file=sys.stderr)
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return 1
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return 0
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if __name__ == '__main__':
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raise SystemExit(main())
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