import contextlib
import importlib
import importlib.util
import os
import platform
import shutil
import subprocess
import tempfile
__all__ = [
"BuildRoot",
]
class BuildRoot(contextlib.AbstractContextManager):
def __init__(self, root, runner, path="/run/osbuild", libdir=None, var="/var/tmp"):
self.root = tempfile.mkdtemp(prefix="osbuild-buildroot-", dir=path)
self.api = tempfile.mkdtemp(prefix="osbuild-api-", dir=path)
self.var = tempfile.mkdtemp(prefix="osbuild-var-", dir=var)
self.mounts = []
self.libdir = libdir
self.runner = runner
self.mount_root(root)
self.mount_var()
def mount_root(self, root):
for p in ["boot", "usr", "bin", "sbin", "lib", "lib64"]:
source = os.path.join(root, p)
target = os.path.join(self.root, p)
if not os.path.isdir(source) or os.path.islink(source):
continue # only bind-mount real dirs
os.mkdir(target)
try:
subprocess.run(["mount", "-o", "bind,ro", source, target], check=True)
except subprocess.CalledProcessError:
self.unmount()
raise
self.mounts.append(target)
if platform.machine() == "s390x" or platform.machine() == "ppc64le":
# work around a combination of systemd not creating the link from
# /lib64 -> /usr/lib64 (see systemd issue #14311) and the dynamic
# linker is being set to (/lib/ld64.so.1 -> /lib64/ld64.so.1)
# on s390x or /lib64/ld64.so.2 on ppc64le
# Therefore we manually create the link before calling nspawn
os.symlink("/usr/lib64", f"{self.root}/lib64")
def mount_var(self):
target = os.path.join(self.root, "var")
os.mkdir(target)
try:
subprocess.run(["mount", "-o", "bind", self.var, target], check=True)
except subprocess.CalledProcessError:
self.unmount()
raise
self.mounts.append(target)
def unmount(self):
for path in self.mounts:
subprocess.run(["umount", "--lazy", path], check=True)
os.rmdir(path)
self.mounts = []
if self.root:
shutil.rmtree(self.root)
self.root = None
if self.api:
shutil.rmtree(self.api)
self.api = None
if self.var:
shutil.rmtree(self.var)
self.var = None
def run(self, argv, binds=None, readonly_binds=None):
"""Runs a command in the buildroot.
Its arguments mean the same as those for subprocess.run().
"""
nspawn_ro_binds = []
# make osbuild API-calls accessible to the container
nspawn_ro_binds.append(f"{self.api}:/run/osbuild/api")
# We want to execute our stages and other scripts in the container. So
# far, we do not install osbuild as a package in the container, but
# provide it from the outside. Therefore, we need to provide `libdir`
# via bind-mount. Furthermore, a system-installed `libdir` has the
# python packages separate in `site-packages`, so we need to bind-mount
# them as well.
# In the future, we want to work towards mandating an osbuild package to
# be installed in the container, so the build is self-contained and does
# not take scripts from the host. However, this requires osbuild
# packaged for those containers. Furthermore, we want to keep supporting
# the current import-model for testing and development.
if self.libdir is not None:
# caller-specified `libdir` must be self-contained
nspawn_ro_binds.append(f"{self.libdir}:/run/osbuild/lib")
else:
# system `libdir` requires importing the python module
nspawn_ro_binds.append("/usr/lib/osbuild:/run/osbuild/lib")
modorigin = importlib.util.find_spec("osbuild").origin
modpath = os.path.dirname(modorigin)
nspawn_ro_binds.append(f"{modpath}:/run/osbuild/lib/osbuild")
return subprocess.run([
"systemd-nspawn",
"--quiet",
"--register=no",
"--keep-unit",
"--as-pid2",
"--link-journal=no",
"--capability=CAP_MAC_ADMIN", # for SELinux labeling
f"--directory={self.root}",
"--setenv=PYTHONPATH=/run/osbuild/lib",
*[f"--bind-ro={b}" for b in nspawn_ro_binds],
*[f"--bind={b}" for b in (binds or [])],
*[f"--bind-ro={b}" for b in (readonly_binds or [])],
f"/run/osbuild/lib/runners/{self.runner}"
] + argv, check=False, stdin=subprocess.DEVNULL)
def __del__(self):
self.unmount()
def __exit__(self, exc_type, exc_value, exc_tb):
self.unmount()