206 lines
7.0 KiB
Python
206 lines
7.0 KiB
Python
# -*- coding: utf-8 -*-
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import os
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import shutil
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import subprocess
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import sys
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from enum import Enum
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from lxcmgr import lxcmgr
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from lxcmgr.paths import LXC_STORAGE_DIR
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from lxcmgr.pkgmgr import PkgMgr
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class ImageExistsError(Exception):
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pass
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class ImageNotFoundError(Exception):
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pass
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class BuildType(Enum):
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NORMAL = 1
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FORCE = 2
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SCRATCH = 3
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METADATA = 4
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class ImageBuilder:
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def __init__(self, image):
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self.image = image
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self.script = []
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self.script_eof = None
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def build(self):
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# Read and process lines from lxcfile
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with open(self.image.lxcfile, 'r') as f:
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for line in f:
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line = line.strip()
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if self.script_eof:
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if line == self.script_eof:
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self.script_eof = None
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self.run_script(self.script)
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else:
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self.script.append(line)
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elif line:
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self.process_line(*line.split(None, 1))
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def process_line(self, directive, args):
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# Process directives from lxcfile
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if 'RUN' == directive:
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self.script = []
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self.script_eof = args
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elif 'IMAGE' == directive:
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self.set_name(args)
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elif 'FROM' == directive:
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self.set_layers(args)
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elif 'COPY' == directive:
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srcdst = args.split()
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self.copy_files(srcdst[0], srcdst[1] if len(srcdst) == 2 else '')
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elif 'ENV' == directive:
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self.add_env(*args.split(None, 1))
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elif 'USER' == directive:
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self.set_user(*args.split())
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elif 'CMD' == directive:
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self.set_cmd(args)
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elif 'WORKDIR' == directive:
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self.set_cwd(args)
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elif 'HALT' == directive:
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self.set_halt(args)
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elif 'READY' == directive:
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self.set_ready(args)
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def get_layer_path(self, layer):
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return os.path.join(LXC_STORAGE_DIR, layer)
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def run_script(self, script):
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# Creates a temporary container, runs a script in its namespace, and stores the modifications as part of the image
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if self.image.build_type == BuildType.METADATA:
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# Don't run anything if we're building just metadata
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return
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lxcmgr.create_container(self.image.name, self.image.conf)
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sh = os.path.join(LXC_STORAGE_DIR, self.image.name, 'run.sh')
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with open(sh, 'w') as f:
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f.write('#!/bin/sh\nset -ev\n\n{}\n'.format('\n'.join(script)))
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os.chmod(sh, 0o700)
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os.chown(sh, 100000, 100000)
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subprocess.run(['lxc-execute', self.image.name, '--', '/bin/sh', '-lc', '/run.sh'], check=True)
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os.unlink(sh)
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if not self.image.build_type == BuildType.SCRATCH:
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# Don't delete the temporary container if we're doing scratch build
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lxcmgr.destroy_container(self.image.name)
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def set_name(self, name):
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# Set name and first (topmost) layer of the image
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self.image.name = name
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self.image.conf['layers'] = [name]
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if self.image.build_type == BuildType.METADATA:
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# Don't check or create any directories if we're building just metadata
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return
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image_path = self.get_layer_path(name)
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if os.path.exists(image_path):
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if self.image.build_type in (BuildType.FORCE, BuildType.SCRATCH):
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self.clean()
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else:
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raise ImageExistsError(image_path)
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os.makedirs(image_path, 0o755, True)
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os.chown(image_path, 100000, 100000)
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def set_layers(self, image):
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# Extend list of layers with the list of layers from parent image
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# Raies an exception when IMAGE has no name
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pkgmgr = PkgMgr()
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self.image.conf['layers'].extend(pkgmgr.installed_packages['images'][image]['layers'])
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def copy_files(self, src, dst):
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# Copy files from the host or download them from a http(s) URL
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if self.image.build_type == BuildType.METADATA:
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# Don't copy anything if we're building just metadata
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return
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dst = os.path.join(LXC_STORAGE_DIR, self.image.name, dst)
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if src.startswith('http://') or src.startswith('https://'):
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unpack_http_archive(src, dst)
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else:
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copy_tree(os.path.join(self.image.build_dir, src), dst)
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# Shift UID/GID of the files to the unprivileged range
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shift_uid(dst)
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def add_env(self, key, value):
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# Sets lxc.environment records for the image
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if 'env' not in self.image.conf:
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self.image.conf['env'] = []
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self.image.conf['env'].append([key, value])
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def set_user(self, uid, gid):
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# Sets lxc.init.uid/gid for the image
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self.image.conf['uid'] = uid
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self.image.conf['gid'] = gid
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def set_cmd(self, cmd):
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# Sets lxc.init.cmd for the image
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self.image.conf['cmd'] = cmd
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def set_cwd(self, cwd):
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# Sets lxc.init.cwd for the image
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self.image.conf['cwd'] = cwd
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def set_halt(self, halt):
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# Sets lxc.signal.halt for the image
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self.image.conf['halt'] = halt
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def set_ready(self, cmd):
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# Sets a command performed in OpenRC start_post to check readiness of the container
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self.image.conf['ready'] = cmd
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def clean(self):
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lxcmgr.destroy_container(self.image.name)
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try:
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shutil.rmtree(self.get_layer_path(self.image.name))
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except FileNotFoundError:
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pass
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def unpack_http_archive(src, dst):
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# Decompress an archive downloaded via http(s)
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xf = 'xzf'
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if src.endswith('.bz2'):
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xf = 'xjf'
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elif src.endswith('.xz'):
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xf = 'xJf'
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with subprocess.Popen(['wget', src, '-O', '-'], stdout=subprocess.PIPE) as wget:
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with subprocess.Popen(['tar', xf, '-', '-C', dst], stdin=wget.stdout) as tar:
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wget.stdout.close()
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tar.wait()
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def copy_tree(src, dst):
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# Copies files from the host
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if not os.path.isdir(src):
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shutil.copy2(src, dst)
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else:
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os.makedirs(dst, exist_ok=True)
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for name in os.listdir(src):
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copy_tree(os.path.join(src, name), os.path.join(dst, name))
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shutil.copystat(src, dst)
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def shift_uid(dir):
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# Shifts UID/GID of a file or a directory and its contents to the unprivileged range
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shift_uid_entry(dir, os.stat(dir, follow_symlinks=True))
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shift_uid_recursively(dir)
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def shift_uid_recursively(dir):
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# Shifts UID/GID of a directory and its contents to the unprivileged range
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for entry in os.scandir(dir):
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shift_uid_entry(entry.path, entry.stat(follow_symlinks=False))
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if entry.is_dir():
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shift_uid_recursively(entry.path)
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def shift_uid_entry(path, stat):
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# Shifts UID/GID of a file or a directory to the unprivileged range
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uid = stat.st_uid
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gid = stat.st_gid
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do_chown = False
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if uid < 100000:
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uid = uid + 100000
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do_chown = True
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if gid < 100000:
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gid = gid + 100000
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do_chown = True
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if do_chown:
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os.lchown(path, uid, gid)
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