Implement custom systemd-boot module that generates user friendly bootloader entries
This commit is contained in:
Michael Smith
433
modules/systemd-boot/systemd-boot-builder.py
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433
modules/systemd-boot/systemd-boot-builder.py
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@@ -0,0 +1,433 @@
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#! @python3@/bin/python3 -B
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import argparse
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import ctypes
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import datetime
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import errno
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import glob
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import os
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import os.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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import warnings
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import json
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from typing import NamedTuple, Any
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from dataclasses import dataclass
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# These values will be replaced with actual values during the package build
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EFI_SYS_MOUNT_POINT = "@efiSysMountPoint@"
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BOOT_MOUNT_POINT = "@bootMountPoint@"
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LOADER_CONF = f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf" # Always stored on the ESP
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NIXOS_DIR = "@nixosDir@"
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TIMEOUT = "@timeout@"
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EDITOR = "@editor@" == "1" # noqa: PLR0133
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CONSOLE_MODE = "@consoleMode@"
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BOOTSPEC_TOOLS = "@bootspecTools@"
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DISTRO_NAME = "@distroName@"
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NIX = "@nix@"
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SYSTEMD = "@systemd@"
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CONFIGURATION_LIMIT = int("@configurationLimit@")
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REBOOT_FOR_BITLOCKER = bool("@rebootForBitlocker@")
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CAN_TOUCH_EFI_VARIABLES = "@canTouchEfiVariables@"
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GRACEFUL = "@graceful@"
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COPY_EXTRA_FILES = "@copyExtraFiles@"
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CHECK_MOUNTPOINTS = "@checkMountpoints@"
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@dataclass
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class BootSpec:
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init: str
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initrd: str
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kernel: str
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kernelParams: list[str] # noqa: N815
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label: str
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system: str
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toplevel: str
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specialisations: dict[str, "BootSpec"]
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sortKey: str # noqa: N815
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devicetree: str | None = None # noqa: N815
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initrdSecrets: str | None = None # noqa: N815
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libc = ctypes.CDLL("libc.so.6")
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FILE = None | int
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def run(cmd: list[str], stdout: FILE = None) -> subprocess.CompletedProcess[str]:
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return subprocess.run(cmd, check=True, text=True, stdout=stdout)
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class SystemIdentifier(NamedTuple):
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profile: str | None
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generation: int
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specialisation: str | None
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def copy_if_not_exists(source: str, dest: str) -> None:
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if not os.path.exists(dest):
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shutil.copyfile(source, dest)
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def generation_dir(profile: str | None, generation: int) -> str:
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if profile:
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return "/nix/var/nix/profiles/system-profiles/%s-%d-link" % (profile, generation)
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else:
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return "/nix/var/nix/profiles/system-%d-link" % (generation)
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def system_dir(profile: str | None, generation: int, specialisation: str | None) -> str:
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d = generation_dir(profile, generation)
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if specialisation:
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return os.path.join(d, "specialisation", specialisation)
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else:
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return d
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BOOT_ENTRY = """title {title} Update {generation}
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sort-key {sort_key}
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version {pretty_build_time}
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linux {kernel}
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initrd {initrd}
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options {kernel_params}
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"""
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def generation_conf_filename(profile: str | None, generation: int, specialisation: str | None) -> str:
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pieces = [
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"nixos",
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profile or None,
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"generation",
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str(generation),
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f"specialisation-{specialisation}" if specialisation else None,
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]
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return "-".join(p for p in pieces if p) + ".conf"
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def write_loader_conf(profile: str | None, generation: int, specialisation: str | None) -> None:
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with open(f"{LOADER_CONF}.tmp", 'w') as f:
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f.write(f"timeout {TIMEOUT}\n")
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f.write("default %s\n" % generation_conf_filename(profile, generation, specialisation))
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if not EDITOR:
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f.write("editor 0\n")
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if REBOOT_FOR_BITLOCKER:
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f.write("reboot-for-bitlocker yes\n");
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f.write(f"console-mode {CONSOLE_MODE}\n")
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f.flush()
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os.fsync(f.fileno())
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os.rename(f"{LOADER_CONF}.tmp", LOADER_CONF)
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def get_bootspec(profile: str | None, generation: int) -> BootSpec:
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system_directory = system_dir(profile, generation, None)
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boot_json_path = os.path.realpath("%s/%s" % (system_directory, "boot.json"))
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if os.path.isfile(boot_json_path):
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boot_json_f = open(boot_json_path, 'r')
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bootspec_json = json.load(boot_json_f)
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else:
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boot_json_str = run(
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[
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f"{BOOTSPEC_TOOLS}/bin/synthesize",
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"--version",
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"1",
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system_directory,
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"/dev/stdout",
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],
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stdout=subprocess.PIPE,
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).stdout
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bootspec_json = json.loads(boot_json_str)
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return bootspec_from_json(bootspec_json)
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def bootspec_from_json(bootspec_json: dict[str, Any]) -> BootSpec:
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specialisations = bootspec_json['org.nixos.specialisation.v1']
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specialisations = {k: bootspec_from_json(v) for k, v in specialisations.items()}
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systemdBootExtension = bootspec_json.get('org.nixos.systemd-boot', {})
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sortKey = systemdBootExtension.get('sortKey', 'nixos')
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devicetree = systemdBootExtension.get('devicetree')
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return BootSpec(
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**bootspec_json['org.nixos.bootspec.v1'],
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specialisations=specialisations,
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sortKey=sortKey,
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devicetree=devicetree,
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)
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def copy_from_file(file: str, dry_run: bool = False) -> str:
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store_file_path = os.path.realpath(file)
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suffix = os.path.basename(store_file_path)
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store_dir = os.path.basename(os.path.dirname(store_file_path))
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efi_file_path = f"{NIXOS_DIR}/{store_dir}-{suffix}.efi"
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if not dry_run:
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copy_if_not_exists(store_file_path, f"{BOOT_MOUNT_POINT}{efi_file_path}")
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return efi_file_path
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def write_entry(profile: str | None, generation: int, specialisation: str | None,
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machine_id: str, bootspec: BootSpec, current: bool) -> None:
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if specialisation:
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bootspec = bootspec.specialisations[specialisation]
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kernel = copy_from_file(bootspec.kernel)
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initrd = copy_from_file(bootspec.initrd)
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devicetree = copy_from_file(bootspec.devicetree) if bootspec.devicetree is not None else None
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title = "{name}{profile}{specialisation}".format(
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name=DISTRO_NAME,
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profile=" [" + profile + "]" if profile else "",
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specialisation=" (%s)" % specialisation if specialisation else "")
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try:
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if bootspec.initrdSecrets is not None:
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run([bootspec.initrdSecrets, f"{BOOT_MOUNT_POINT}%s" % (initrd)])
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except subprocess.CalledProcessError:
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if current:
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print("failed to create initrd secrets!", file=sys.stderr)
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sys.exit(1)
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else:
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print("warning: failed to create initrd secrets "
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f'for "{title} - Configuration {generation}", an older generation', file=sys.stderr)
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print("note: this is normal after having removed "
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"or renamed a file in `boot.initrd.secrets`", file=sys.stderr)
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entry_file = f"{BOOT_MOUNT_POINT}/loader/entries/%s" % (
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generation_conf_filename(profile, generation, specialisation))
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tmp_path = "%s.tmp" % (entry_file)
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kernel_params = "init=%s " % bootspec.init
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kernel_params = kernel_params + " ".join(bootspec.kernelParams)
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build_time = int(os.path.getctime(system_dir(profile, generation, specialisation)))
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pretty_build_time = datetime.datetime.fromtimestamp(build_time).strftime('%x %X')
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with open(tmp_path, 'w') as f:
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f.write(BOOT_ENTRY.format(title=title,
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sort_key=bootspec.sortKey,
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generation=generation,
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kernel=kernel,
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initrd=initrd,
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kernel_params=kernel_params,
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pretty_build_time=pretty_build_time))
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if machine_id is not None:
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f.write("machine-id %s\n" % machine_id)
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if devicetree is not None:
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f.write("devicetree %s\n" % devicetree)
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f.flush()
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os.fsync(f.fileno())
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os.rename(tmp_path, entry_file)
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def get_generations(profile: str | None = None) -> list[SystemIdentifier]:
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gen_list = run(
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[
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f"{NIX}/bin/nix-env",
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"--list-generations",
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"-p",
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"/nix/var/nix/profiles/%s"
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% ("system-profiles/" + profile if profile else "system"),
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],
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stdout=subprocess.PIPE,
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).stdout
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gen_lines = gen_list.split("\n")
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gen_lines.pop()
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configurationLimit = CONFIGURATION_LIMIT
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configurations = [
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SystemIdentifier(
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profile=profile,
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generation=int(line.split()[0]),
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specialisation=None
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)
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for line in gen_lines
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]
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return configurations[-configurationLimit:]
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def remove_old_entries(gens: list[SystemIdentifier]) -> None:
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rex_profile = re.compile(r"^" + re.escape(BOOT_MOUNT_POINT) + r"/loader/entries/nixos-(.*)-generation-.*\.conf$")
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rex_generation = re.compile(r"^" + re.escape(BOOT_MOUNT_POINT) + r"/loader/entries/nixos.*-generation-([0-9]+)(-specialisation-.*)?\.conf$")
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known_paths = []
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for gen in gens:
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bootspec = get_bootspec(gen.profile, gen.generation)
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known_paths.append(copy_from_file(bootspec.kernel, True))
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known_paths.append(copy_from_file(bootspec.initrd, True))
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for path in glob.iglob(f"{BOOT_MOUNT_POINT}/loader/entries/nixos*-generation-[1-9]*.conf"):
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if rex_profile.match(path):
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prof = rex_profile.sub(r"\1", path)
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else:
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prof = None
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try:
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gen_number = int(rex_generation.sub(r"\1", path))
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except ValueError:
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continue
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if (prof, gen_number, None) not in gens:
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os.unlink(path)
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for path in glob.iglob(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/*"):
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if path not in known_paths and not os.path.isdir(path):
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os.unlink(path)
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def cleanup_esp() -> None:
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for path in glob.iglob(f"{EFI_SYS_MOUNT_POINT}/loader/entries/nixos*"):
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os.unlink(path)
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if os.path.isdir(f"{EFI_SYS_MOUNT_POINT}/{NIXOS_DIR}"):
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shutil.rmtree(f"{EFI_SYS_MOUNT_POINT}/{NIXOS_DIR}")
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def get_profiles() -> list[str]:
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if os.path.isdir("/nix/var/nix/profiles/system-profiles/"):
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return [x
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for x in os.listdir("/nix/var/nix/profiles/system-profiles/")
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if not x.endswith("-link")]
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else:
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return []
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def install_bootloader(args: argparse.Namespace) -> None:
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try:
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with open("/etc/machine-id") as machine_file:
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machine_id = machine_file.readlines()[0]
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except IOError as e:
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if e.errno != errno.ENOENT:
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raise
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# Since systemd version 232 a machine ID is required and it might not
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# be there on newly installed systems, so let's generate one so that
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# bootctl can find it and we can also pass it to write_entry() later.
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cmd = [f"{SYSTEMD}/bin/systemd-machine-id-setup", "--print"]
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machine_id = run(cmd, stdout=subprocess.PIPE).stdout.rstrip()
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if os.getenv("NIXOS_INSTALL_GRUB") == "1":
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warnings.warn("NIXOS_INSTALL_GRUB env var deprecated, use NIXOS_INSTALL_BOOTLOADER", DeprecationWarning)
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os.environ["NIXOS_INSTALL_BOOTLOADER"] = "1"
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# flags to pass to bootctl install/update
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bootctl_flags = []
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if BOOT_MOUNT_POINT != EFI_SYS_MOUNT_POINT:
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bootctl_flags.append(f"--boot-path={BOOT_MOUNT_POINT}")
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if CAN_TOUCH_EFI_VARIABLES != "1":
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bootctl_flags.append("--no-variables")
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if GRACEFUL == "1":
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bootctl_flags.append("--graceful")
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if os.getenv("NIXOS_INSTALL_BOOTLOADER") == "1":
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# bootctl uses fopen() with modes "wxe" and fails if the file exists.
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if os.path.exists(LOADER_CONF):
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os.unlink(LOADER_CONF)
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run(
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[f"{SYSTEMD}/bin/bootctl", f"--esp-path={EFI_SYS_MOUNT_POINT}"]
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+ bootctl_flags
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+ ["install"]
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)
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else:
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# Update bootloader to latest if needed
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available_out = run(
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[f"{SYSTEMD}/bin/bootctl", "--version"], stdout=subprocess.PIPE
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).stdout.split()[2]
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installed_out = run(
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[f"{SYSTEMD}/bin/bootctl", f"--esp-path={EFI_SYS_MOUNT_POINT}", "status"],
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stdout=subprocess.PIPE,
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).stdout
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# See status_binaries() in systemd bootctl.c for code which generates this
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# Matches
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# Available Boot Loaders on ESP:
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# ESP: /boot (/dev/disk/by-partuuid/9b39b4c4-c48b-4ebf-bfea-a56b2395b7e0)
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# File: └─/EFI/systemd/systemd-bootx64.efi (systemd-boot 255.2)
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# But also:
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# Available Boot Loaders on ESP:
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# ESP: /boot (/dev/disk/by-partuuid/9b39b4c4-c48b-4ebf-bfea-a56b2395b7e0)
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# File: ├─/EFI/systemd/HashTool.efi
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# └─/EFI/systemd/systemd-bootx64.efi (systemd-boot 255.2)
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installed_match = re.search(r"^\W+.*/EFI/(?:BOOT|systemd)/.*\.efi \(systemd-boot ([\d.]+[^)]*)\)$",
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installed_out, re.IGNORECASE | re.MULTILINE)
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available_match = re.search(r"^\((.*)\)$", available_out)
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if installed_match is None:
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raise Exception("could not find any previously installed systemd-boot")
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if available_match is None:
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raise Exception("could not determine systemd-boot version")
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installed_version = installed_match.group(1)
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available_version = available_match.group(1)
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if installed_version < available_version:
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print("updating systemd-boot from %s to %s" % (installed_version, available_version))
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run(
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[f"{SYSTEMD}/bin/bootctl", f"--esp-path={EFI_SYS_MOUNT_POINT}"]
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+ bootctl_flags
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+ ["update"]
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)
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os.makedirs(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}", exist_ok=True)
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os.makedirs(f"{BOOT_MOUNT_POINT}/loader/entries", exist_ok=True)
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gens = get_generations()
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for profile in get_profiles():
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gens += get_generations(profile)
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remove_old_entries(gens)
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for gen in gens:
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try:
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bootspec = get_bootspec(gen.profile, gen.generation)
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is_default = os.path.dirname(bootspec.init) == args.default_config
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write_entry(*gen, machine_id, bootspec, current=is_default)
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for specialisation in bootspec.specialisations.keys():
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write_entry(gen.profile, gen.generation, specialisation, machine_id, bootspec, current=is_default)
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if is_default:
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write_loader_conf(*gen)
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except OSError as e:
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# See https://github.com/NixOS/nixpkgs/issues/114552
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if e.errno == errno.EINVAL:
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profile = f"profile '{gen.profile}'" if gen.profile else "default profile"
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print("ignoring {} in the list of boot entries because of the following error:\n{}".format(profile, e), file=sys.stderr)
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else:
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raise e
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if BOOT_MOUNT_POINT != EFI_SYS_MOUNT_POINT:
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# Cleanup any entries in ESP if xbootldrMountPoint is set.
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# If the user later unsets xbootldrMountPoint, entries in XBOOTLDR will not be cleaned up
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# automatically, as we don't have information about the mount point anymore.
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cleanup_esp()
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for root, _, files in os.walk(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/.extra-files", topdown=False):
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relative_root = root.removeprefix(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/.extra-files").removeprefix("/")
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actual_root = os.path.join(f"{BOOT_MOUNT_POINT}", relative_root)
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for file in files:
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actual_file = os.path.join(actual_root, file)
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if os.path.exists(actual_file):
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os.unlink(actual_file)
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os.unlink(os.path.join(root, file))
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if not len(os.listdir(actual_root)):
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os.rmdir(actual_root)
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os.rmdir(root)
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os.makedirs(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/.extra-files", exist_ok=True)
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run([COPY_EXTRA_FILES])
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def main() -> None:
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parser = argparse.ArgumentParser(description=f"Update {DISTRO_NAME}-related systemd-boot files")
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parser.add_argument('default_config', metavar='DEFAULT-CONFIG', help=f"The default {DISTRO_NAME} config to boot")
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args = parser.parse_args()
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run([CHECK_MOUNTPOINTS])
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try:
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install_bootloader(args)
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finally:
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# Since fat32 provides little recovery facilities after a crash,
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# it can leave the system in an unbootable state, when a crash/outage
|
||||
# happens shortly after an update. To decrease the likelihood of this
|
||||
# event sync the efi filesystem after each update.
|
||||
rc = libc.syncfs(os.open(f"{BOOT_MOUNT_POINT}", os.O_RDONLY))
|
||||
if rc != 0:
|
||||
print(f"could not sync {BOOT_MOUNT_POINT}: {os.strerror(rc)}", file=sys.stderr)
|
||||
|
||||
if BOOT_MOUNT_POINT != EFI_SYS_MOUNT_POINT:
|
||||
rc = libc.syncfs(os.open(EFI_SYS_MOUNT_POINT, os.O_RDONLY))
|
||||
if rc != 0:
|
||||
print(f"could not sync {EFI_SYS_MOUNT_POINT}: {os.strerror(rc)}", file=sys.stderr)
|
||||
|
||||
|
||||
if __name__ == '__main__':
|
||||
main()
|
||||
Reference in New Issue
Block a user