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feat: enhance Ubuntu rootfs build process with improved logging and error handling

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kstyagi
2026-09-22 09:30:55 +05:30
parent 1d3644ab7c
commit bd92573158
5 changed files with 273 additions and 62 deletions
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uvm/install.py
+107 -32
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@@ -3,6 +3,7 @@
from __future__ import annotations
import os
import shlex
import shutil
import tarfile
import tempfile
@@ -20,7 +21,7 @@ from .system import CommandRunner, check_kvm, ensure_data_directories, require_r
_UBUNTU_RELEASE = "jammy"
_ROOTFS_RECIPE = "uvm-ubuntu-jammy-v1\n"
_ROOTFS_RECIPE = "uvm-ubuntu-jammy-v2\n"
_GUEST_PACKAGES = (
"ca-certificates", "openssh-server", "sudo", "systemd-sysv", "udev",
"dbus", "libpam-systemd", "iproute2", "iputils-ping", "curl",
@@ -30,6 +31,24 @@ _EXT4_FEATURES = (
"none,has_journal,ext_attr,resize_inode,dir_index,filetype,extent,64bit,"
"flex_bg,sparse_super,large_file,huge_file,dir_nlink,extra_isize,metadata_csum"
)
_ROOTFS_NAMESPACE = (
"unshare", "--mount", "--propagation", "private", "--pid", "--fork",
"--kill-child", "--mount-proc",
)
_GUEST_APT_SCRIPT = """\
root=$1
shift
mount --rbind /dev "$root/dev"
mount --make-rslave "$root/dev"
mount -t proc proc "$root/proc"
mount -t sysfs -o ro sysfs "$root/sys"
chroot "$root" /usr/bin/env DEBIAN_FRONTEND=noninteractive LC_ALL=C \\
apt-get -o APT::Update::Error-Mode=any update
chroot "$root" /usr/bin/env DEBIAN_FRONTEND=noninteractive LC_ALL=C \\
apt-get -y -o Dpkg::Options::=--force-confold dist-upgrade
chroot "$root" /usr/bin/env DEBIAN_FRONTEND=noninteractive LC_ALL=C \\
apt-get -y --no-install-recommends install "$@"
"""
class Installer:
@@ -258,33 +277,36 @@ class Installer:
with tempfile.TemporaryDirectory(prefix=".ubuntu-build-", dir=destination.parent) as name:
temporary = Path(name)
root = temporary / "root"
policy = root / "usr/sbin/policy-rc.d"
policy.parent.mkdir(parents=True)
policy.write_text("#!/bin/sh\nexit 101\n", encoding="utf-8")
policy.chmod(0o755)
# Package scripts run natively, with private mounts/PIDs and service startup disabled.
self._runner.run((
"unshare", "--mount", "--propagation", "private", "--pid", "--fork",
"--kill-child", "--mount-proc", "env", "DEBIAN_FRONTEND=noninteractive",
"debootstrap", f"--arch={architecture}", "--variant=minbase", "--merged-usr",
"--components=main,universe", f"--include={','.join(_GUEST_PACKAGES)}",
f"--extra-suites={_UBUNTU_RELEASE}-updates,{_UBUNTU_RELEASE}-security",
"--force-check-gpg", "--keyring=/usr/share/keyrings/ubuntu-archive-keyring.gpg",
_UBUNTU_RELEASE, root, mirror,
))
policy.unlink()
self._configure_ubuntu_rootfs(root, mirror)
self._validate_ubuntu_rootfs(root)
build_log = temporary / "build.log"
try:
# Bootstrap one consistent release; apt resolves updated package versions later.
self._run_rootfs_stage("Ubuntu bootstrap", (
*_ROOTFS_NAMESPACE, "env", "DEBIAN_FRONTEND=noninteractive",
"debootstrap", f"--arch={architecture}", "--variant=minbase", "--merged-usr",
"--components=main", "--include=ca-certificates,ubuntu-keyring",
"--force-check-gpg", "--keyring=/usr/share/keyrings/ubuntu-archive-keyring.gpg",
_UBUNTU_RELEASE, root, mirror,
), build_log)
self._install_ubuntu_packages(root, mirror, build_log)
self._configure_ubuntu_rootfs(root)
self._validate_ubuntu_rootfs(root)
disk = temporary / "rootfs.ext4"
with disk.open("wb") as image:
image.truncate(2 * 1024 * 1024 * 1024)
disk.chmod(0o600)
self._runner.run((
"mkfs.ext4", "-q", "-F", "-b", "4096", "-O", _EXT4_FEATURES,
"-E", "lazy_itable_init=0,lazy_journal_init=0", "-d", root, disk,
), capture=True)
self._runner.run(("e2fsck", "-f", "-n", disk), capture=True)
disk = temporary / "rootfs.ext4"
with disk.open("wb") as image:
image.truncate(2 * 1024 * 1024 * 1024)
disk.chmod(0o600)
self._run_rootfs_stage("Ubuntu ext4 formatting", (
"mkfs.ext4", "-q", "-F", "-b", "4096", "-O", _EXT4_FEATURES,
"-E", "lazy_itable_init=0,lazy_journal_init=0", "-d", root, disk,
), build_log)
self._run_rootfs_stage("Ubuntu filesystem check", ("e2fsck", "-f", "-n", disk), build_log)
except (UvmError, OSError, UnicodeError) as error:
try:
log = self._save_rootfs_build_log(destination, root, build_log, error=error)
except OSError as log_error:
raise UvmError(f"Ubuntu rootfs build failed: {error}; could not save diagnostics: {log_error}") from error
raise UvmError(f"Ubuntu rootfs build failed: {error}; details saved to {log}") from error
self._save_rootfs_build_log(destination, root, build_log)
with disk.open("rb") as image:
os.fsync(image.fileno())
os.replace(disk, destination)
@@ -296,12 +318,65 @@ class Installer:
except (OSError, UnicodeError) as error:
raise UvmError(f"could not build Ubuntu guest rootfs: {error}") from error
def _configure_ubuntu_rootfs(self, root: Path, mirror: str) -> None:
def _install_ubuntu_packages(self, root: Path, mirror: str, build_log: Path) -> None:
sources = root / "etc/apt/sources.list"
sources.write_text("".join(
f"deb {mirror} {suite} main universe\n"
for suite in (_UBUNTU_RELEASE, f"{_UBUNTU_RELEASE}-updates", f"{_UBUNTU_RELEASE}-security")
), encoding="utf-8")
sources.chmod(0o644)
# Ubuntu's debootstrap script removes its own policy-rc.d on success.
policy = root / "usr/sbin/policy-rc.d"
policy.write_text("#!/bin/sh\nexit 101\n", encoding="utf-8")
policy.chmod(0o755)
try:
self._run_rootfs_stage("Ubuntu guest package installation", (
*_ROOTFS_NAMESPACE, "/bin/sh", "-eu", "-c", _GUEST_APT_SCRIPT,
"uvm-guest-packages", root, *_GUEST_PACKAGES,
), build_log)
finally:
policy.unlink(missing_ok=True)
def _run_rootfs_stage(self, stage: str, command: tuple[str | Path, ...], log: Path) -> None:
if self._emit is not None:
self._emit(stage)
with log.open("a", encoding="utf-8") as output:
output.write(f"\n=== {stage} ===\n+ {shlex.join(map(str, command))}\n")
result = self._runner.run(command, check=False, capture=True)
output.write(result.stdout)
output.write(result.stderr)
if result.returncode != 0:
raise UvmError(f"{stage} failed (exit {result.returncode})")
@staticmethod
def _save_rootfs_build_log(destination: Path, root: Path, build_log: Path, *, error: Exception | None = None) -> Path:
log = destination.with_name("ubuntu-build.log")
descriptor, name = tempfile.mkstemp(prefix=".ubuntu-log-", dir=destination.parent)
temporary = Path(name)
try:
with os.fdopen(descriptor, "wb") as output:
# Completed bootstrap details precede apt output; failed bootstrap details follow it.
for source in (root / "var/log/bootstrap.log", build_log, root / "debootstrap/debootstrap.log"):
if source.is_file():
output.write(f"\n=== {source.name} ===\n".encode("utf-8"))
with source.open("rb") as content:
shutil.copyfileobj(content, output)
if error is not None:
output.write(f"\nUbuntu rootfs build failed: {error}\n".encode("utf-8", errors="replace"))
output.flush()
os.fsync(output.fileno())
os.replace(temporary, log)
directory = os.open(log.parent, os.O_RDONLY)
try:
os.fsync(directory)
finally:
os.close(directory)
finally:
temporary.unlink(missing_ok=True)
return log
def _configure_ubuntu_rootfs(self, root: Path) -> None:
files = {
"etc/apt/sources.list": "".join(
f"deb {mirror} {suite} main universe\n"
for suite in (_UBUNTU_RELEASE, f"{_UBUNTU_RELEASE}-updates", f"{_UBUNTU_RELEASE}-security")
),
"etc/fstab": "/dev/vda / ext4 defaults 0 1\n",
"etc/hostname": "uvm\n",
"etc/hosts": "127.0.0.1 localhost\n127.0.1.1 uvm\n",