X-Git-Url: http://git.scottworley.com/pinch/blobdiff_plain/3e6421c4c43619da3b8b2501f262c86987f6d1cf..82e0ab64d4d8c449f8239a66ad42b39734c5d351:/pinch.py?ds=sidebyside diff --git a/pinch.py b/pinch.py index f22a1c3..9e80c01 100644 --- a/pinch.py +++ b/pinch.py @@ -1,11 +1,24 @@ +# pinch: PIN CHannels - a replacement for `nix-channel --update` +# +# This program is free software: you can redistribute it and/or modify it +# under the terms of the GNU General Public License as published by the +# Free Software Foundation, version 3. + + +import argparse +import configparser import filecmp import functools +import getpass import hashlib import operator import os import os.path +import shlex import shutil import subprocess +import sys +import tarfile import tempfile import types import urllib.parse @@ -13,32 +26,34 @@ import urllib.request import xml.dom.minidom from typing import ( + Callable, Dict, Iterable, List, + Mapping, + NamedTuple, NewType, - Sequence, + Optional, + Set, Tuple, + Type, + TypeVar, + Union, ) -Digest16 = NewType('Digest16', str) -Digest32 = NewType('Digest32', str) +import git_cache +# Use xdg module when it's less painful to have as a dependency -class InfoTableEntry(types.SimpleNamespace): - digest: Digest16 - file: str - size: int - url: str +class XDG(NamedTuple): + XDG_CACHE_HOME: str -class Info(types.SimpleNamespace): - channel_html: bytes - forwarded_url: str - git_revision: str - release_name: str - table: Dict[str, InfoTableEntry] - url: str + +xdg = XDG( + XDG_CACHE_HOME=os.getenv( + 'XDG_CACHE_HOME', + os.path.expanduser('~/.cache'))) class VerificationError(Exception): @@ -51,19 +66,19 @@ class Verification: self.line_length = 0 def status(self, s: str) -> None: - print(s, end=' ', flush=True) + print(s, end=' ', file=sys.stderr, flush=True) self.line_length += 1 + len(s) # Unicode?? @staticmethod def _color(s: str, c: int) -> str: - return '\033[%2dm%s\033[00m' % (c, s) + return f'\033[{c:2d}m{s}\033[00m' def result(self, r: bool) -> None: message, color = {True: ('OK ', 92), False: ('FAIL', 91)}[r] length = len(message) - cols = shutil.get_terminal_size().columns + cols = shutil.get_terminal_size().columns or 80 pad = (cols - (self.line_length + length)) % cols - print(' ' * pad + self._color(message, color)) + print(' ' * pad + self._color(message, color), file=sys.stderr) self.line_length = 0 if not r: raise VerificationError() @@ -76,10 +91,137 @@ class Verification: self.result(True) -def compare(a: str, - b: str) -> Tuple[Sequence[str], - Sequence[str], - Sequence[str]]: +Digest16 = NewType('Digest16', str) +Digest32 = NewType('Digest32', str) + + +class ChannelTableEntry(types.SimpleNamespace): + absolute_url: str + digest: Digest16 + file: str + size: int + url: str + + +class AliasPin(NamedTuple): + pass + + +class SymlinkPin(NamedTuple): + @property + def release_name(self) -> str: + return 'link' + + +class GitPin(NamedTuple): + git_revision: str + release_name: str + + +class ChannelPin(NamedTuple): + git_revision: str + release_name: str + tarball_url: str + tarball_sha256: str + + +Pin = Union[AliasPin, SymlinkPin, GitPin, ChannelPin] + + +def copy_to_nix_store(v: Verification, filename: str) -> str: + v.status('Putting tarball in Nix store') + process = subprocess.run( + ['nix-store', '--add', filename], stdout=subprocess.PIPE) + v.result(process.returncode == 0) + return process.stdout.decode().strip() # type: ignore # (for old mypy) + + +def symlink_archive(v: Verification, path: str) -> str: + with tempfile.TemporaryDirectory() as td: + archive_filename = os.path.join(td, 'link.tar.gz') + os.symlink(path, os.path.join(td, 'link')) + with tarfile.open(archive_filename, mode='x:gz') as t: + t.add(os.path.join(td, 'link'), arcname='link') + return copy_to_nix_store(v, archive_filename) + + +class AliasSearchPath(NamedTuple): + alias_of: str + + def pin(self, _: Verification, __: Optional[Pin]) -> AliasPin: + return AliasPin() + + +class SymlinkSearchPath(NamedTuple): + path: str + + def pin(self, _: Verification, __: Optional[Pin]) -> SymlinkPin: + return SymlinkPin() + + def fetch(self, v: Verification, _: Pin) -> str: + return symlink_archive(v, self.path) + + +class GitSearchPath(NamedTuple): + git_ref: str + git_repo: str + + def pin(self, v: Verification, old_pin: Optional[Pin]) -> GitPin: + _, new_revision = git_cache.fetch(self.git_repo, self.git_ref) + if old_pin is not None: + assert isinstance(old_pin, GitPin) + verify_git_ancestry(v, self, old_pin.git_revision, new_revision) + return GitPin(release_name=git_revision_name(v, self, new_revision), + git_revision=new_revision) + + def fetch(self, v: Verification, pin: Pin) -> str: + assert isinstance(pin, GitPin) + git_cache.ensure_rev_available( + self.git_repo, self.git_ref, pin.git_revision) + return git_get_tarball(v, self, pin) + + +class ChannelSearchPath(NamedTuple): + channel_url: str + git_ref: str + git_repo: str + + def pin(self, v: Verification, old_pin: Optional[Pin]) -> ChannelPin: + if old_pin is not None: + assert isinstance(old_pin, ChannelPin) + + channel_html, forwarded_url = fetch_channel(v, self) + table, new_gitpin = parse_channel(v, channel_html) + if old_pin is not None and old_pin.git_revision == new_gitpin.git_revision: + return old_pin + fetch_resources(v, new_gitpin, forwarded_url, table) + git_cache.ensure_rev_available( + self.git_repo, self.git_ref, new_gitpin.git_revision) + if old_pin is not None: + verify_git_ancestry( + v, self, old_pin.git_revision, new_gitpin.git_revision) + check_channel_contents(v, self, table, new_gitpin) + return ChannelPin( + release_name=new_gitpin.release_name, + tarball_url=table['nixexprs.tar.xz'].absolute_url, + tarball_sha256=table['nixexprs.tar.xz'].digest, + git_revision=new_gitpin.git_revision) + + def fetch(self, v: Verification, pin: Pin) -> str: + assert isinstance(pin, ChannelPin) + + return fetch_with_nix_prefetch_url( + v, pin.tarball_url, Digest16(pin.tarball_sha256)) + + +SearchPath = Union[AliasSearchPath, + SymlinkSearchPath, + GitSearchPath, + ChannelSearchPath] +TarrableSearchPath = Union[GitSearchPath, ChannelSearchPath] + + +def compare(a: str, b: str) -> Tuple[List[str], List[str], List[str]]: def throw(error: OSError) -> None: raise error @@ -107,49 +249,66 @@ def compare(a: str, return filecmp.cmpfiles(a, b, files, shallow=False) -def fetch(v: Verification, channel_url: str) -> Info: - info = Info() - info.url = channel_url - v.status('Fetching channel') - request = urllib.request.urlopen( - 'https://channels.nixos.org/nixos-20.03', timeout=10) - info.channel_html = request.read() - info.forwarded_url = request.geturl() - v.result(request.status == 200) - v.check('Got forwarded', info.url != info.forwarded_url) - return info +def fetch_channel( + v: Verification, channel: ChannelSearchPath) -> Tuple[str, str]: + v.status(f'Fetching channel from {channel.channel_url}') + with urllib.request.urlopen(channel.channel_url, timeout=10) as request: + channel_html = request.read().decode() + forwarded_url = request.geturl() + v.result(request.status == 200) + v.check('Got forwarded', channel.channel_url != forwarded_url) + return channel_html, forwarded_url -def parse_table(v: Verification, info: Info) -> None: +def parse_channel(v: Verification, channel_html: str) \ + -> Tuple[Dict[str, ChannelTableEntry], GitPin]: v.status('Parsing channel description as XML') - d = xml.dom.minidom.parseString(info.channel_html) + d = xml.dom.minidom.parseString(channel_html) v.ok() - v.status('Extracting release name:') - title_name = d.getElementsByTagName( - 'title')[0].firstChild.nodeValue.split()[2] - h1_name = d.getElementsByTagName('h1')[0].firstChild.nodeValue.split()[2] - v.status(title_name) - v.result(title_name == h1_name) - info.release_name = title_name - - v.status('Extracting git commit:') + v.status('Finding release name (1)') + title = d.getElementsByTagName('title')[0].firstChild + v.result(isinstance(title, xml.dom.minidom.CharacterData)) + assert isinstance(title, xml.dom.minidom.CharacterData) + release_name = title.nodeValue.split()[2] + v.status('Finding release name (2)') + h1 = d.getElementsByTagName('h1')[0].firstChild + v.result(isinstance(h1, xml.dom.minidom.CharacterData)) + assert isinstance(h1, xml.dom.minidom.CharacterData) + v.status('Verifying release name:') + v.status(release_name) + v.result(release_name == h1.nodeValue.split()[2]) + + v.status('Finding git commit') git_commit_node = d.getElementsByTagName('tt')[0] - info.git_commit = git_commit_node.firstChild.nodeValue - v.status(info.git_commit) + v.result( + isinstance( + git_commit_node.firstChild, + xml.dom.minidom.CharacterData)) + assert isinstance( + git_commit_node.firstChild, + xml.dom.minidom.CharacterData) + v.status('Extracting git commit:') + git_revision = git_commit_node.firstChild.nodeValue + v.status(git_revision) v.ok() v.status('Verifying git commit label') v.result(git_commit_node.previousSibling.nodeValue == 'Git commit ') v.status('Parsing table') - info.table = {} + table: Dict[str, ChannelTableEntry] = {} for row in d.getElementsByTagName('tr')[1:]: name = row.childNodes[0].firstChild.firstChild.nodeValue url = row.childNodes[0].firstChild.getAttribute('href') size = int(row.childNodes[1].firstChild.nodeValue) digest = Digest16(row.childNodes[2].firstChild.firstChild.nodeValue) - info.table[name] = InfoTableEntry(url=url, digest=digest, size=size) + table[name] = ChannelTableEntry(url=url, digest=digest, size=size) v.ok() + return table, GitPin(release_name=release_name, git_revision=git_revision) + + +def digest_string(s: bytes) -> Digest16: + return Digest16(hashlib.sha256(s).hexdigest()) def digest_file(filename: str) -> Digest16: @@ -161,18 +320,39 @@ def digest_file(filename: str) -> Digest16: return Digest16(hasher.hexdigest()) +@functools.lru_cache +def _experimental_flag_needed(v: Verification) -> bool: + v.status('Checking Nix version') + process = subprocess.run(['nix', '--help'], stdout=subprocess.PIPE) + v.result(process.returncode == 0) + return b'--experimental-features' in process.stdout + + +def _nix_command(v: Verification) -> List[str]: + return ['nix', '--experimental-features', + 'nix-command'] if _experimental_flag_needed(v) else ['nix'] + + def to_Digest16(v: Verification, digest32: Digest32) -> Digest16: v.status('Converting digest to base16') - process = subprocess.run( - ['nix', 'to-base16', '--type', 'sha256', digest32], capture_output=True) + process = subprocess.run(_nix_command(v) + [ + 'to-base16', + '--type', + 'sha256', + digest32], + stdout=subprocess.PIPE) v.result(process.returncode == 0) return Digest16(process.stdout.decode().strip()) def to_Digest32(v: Verification, digest16: Digest16) -> Digest32: v.status('Converting digest to base32') - process = subprocess.run( - ['nix', 'to-base32', '--type', 'sha256', digest16], capture_output=True) + process = subprocess.run(_nix_command(v) + [ + 'to-base32', + '--type', + 'sha256', + digest16], + stdout=subprocess.PIPE) v.result(process.returncode == 0) return Digest32(process.stdout.decode().strip()) @@ -181,47 +361,363 @@ def fetch_with_nix_prefetch_url( v: Verification, url: str, digest: Digest16) -> str: - v.status('Fetching %s' % url) + v.status(f'Fetching {url}') process = subprocess.run( - ['nix-prefetch-url', '--print-path', url, digest], capture_output=True) + ['nix-prefetch-url', '--print-path', url, digest], stdout=subprocess.PIPE) v.result(process.returncode == 0) prefetch_digest, path, empty = process.stdout.decode().split('\n') assert empty == '' v.check("Verifying nix-prefetch-url's digest", to_Digest16(v, Digest32(prefetch_digest)) == digest) - v.status("Verifying file digest") + v.status(f"Verifying digest of {path}") file_digest = digest_file(path) v.result(file_digest == digest) - return path + return path # type: ignore # (for old mypy) -def fetch_resources(v: Verification, info: Info) -> None: +def fetch_resources( + v: Verification, + pin: GitPin, + forwarded_url: str, + table: Dict[str, ChannelTableEntry]) -> None: for resource in ['git-revision', 'nixexprs.tar.xz']: - fields = info.table[resource] - url = urllib.parse.urljoin(info.forwarded_url, fields.url) - fields.file = fetch_with_nix_prefetch_url(v, url, fields.digest) + fields = table[resource] + fields.absolute_url = urllib.parse.urljoin(forwarded_url, fields.url) + fields.file = fetch_with_nix_prefetch_url( + v, fields.absolute_url, fields.digest) v.status('Verifying git commit on main page matches git commit in table') - v.result( - open( - info.table['git-revision'].file).read(999) == info.git_commit) + with open(table['git-revision'].file, encoding='utf-8') as rev_file: + v.result(rev_file.read(999) == pin.git_revision) + + +def tarball_cache_file(channel: TarrableSearchPath, pin: GitPin) -> str: + return os.path.join( + xdg.XDG_CACHE_HOME, + 'pinch/git-tarball', + f'{digest_string(channel.git_repo.encode())}-{pin.git_revision}-{pin.release_name}') + + +def verify_git_ancestry( + v: Verification, + channel: TarrableSearchPath, + old_revision: str, + new_revision: str) -> None: + cachedir = git_cache.git_cachedir(channel.git_repo) + v.status(f'Verifying rev is an ancestor of previous rev {old_revision}') + process = subprocess.run(['git', + '-C', + cachedir, + 'merge-base', + '--is-ancestor', + old_revision, + new_revision]) + v.result(process.returncode == 0) + + +def broken_symlinks_are_identical(root1: str, root2: str, path: str) -> bool: + a = os.path.join(root1, path) + b = os.path.join(root2, path) + return (os.path.islink(a) + and os.path.islink(b) + and not os.path.exists(a) + and not os.path.exists(b) + and os.readlink(a) == os.readlink(b)) -def extract_channel(v: Verification, info: Info) -> None: - with tempfile.TemporaryDirectory() as d: - v.status('Extracting %s' % info.table['nixexprs.tar.xz'].file) - shutil.unpack_archive(info.table['nixexprs.tar.xz'].file, d) - v.ok() - v.status('Removing temporary directory') +def compare_tarball_and_git( + v: Verification, + pin: GitPin, + channel_contents: str, + git_contents: str) -> None: + v.status('Comparing channel tarball with git checkout') + tarball_contents = os.path.join(channel_contents, pin.release_name) + match, mismatch, errors = compare(tarball_contents, git_contents) + v.ok() + v.check(f'{len(match)} files match', len(match) > 0) + v.check(f'{len(mismatch)} files differ', len(mismatch) == 0) + expected_errors = [ + '.git-revision', + '.version-suffix', + 'nixpkgs', + 'programs.sqlite', + 'svn-revision'] + benign_expected_errors = [] + for ee in expected_errors: + if ee in errors: + errors.remove(ee) + benign_expected_errors.append(ee) + errors = [ + e for e in errors + if not broken_symlinks_are_identical(tarball_contents, git_contents, e) + ] + v.check( + f'{len(errors)} unexpected incomparable files: {errors}', + len(errors) == 0) + v.check( + f'({len(benign_expected_errors)} of {len(expected_errors)} expected incomparable files)', + len(benign_expected_errors) == len(expected_errors)) + + +def extract_tarball( + v: Verification, + table: Dict[str, ChannelTableEntry], + dest: str) -> None: + v.status(f"Extracting tarball {table['nixexprs.tar.xz'].file}") + shutil.unpack_archive(table['nixexprs.tar.xz'].file, dest) v.ok() -def main() -> None: +def git_checkout( + v: Verification, + channel: TarrableSearchPath, + pin: GitPin, + dest: str) -> None: + v.status('Checking out corresponding git revision') + with subprocess.Popen( + ['git', '-C', git_cache.git_cachedir(channel.git_repo), 'archive', pin.git_revision], + stdout=subprocess.PIPE) as git: + with subprocess.Popen(['tar', 'x', '-C', dest, '-f', '-'], stdin=git.stdout) as tar: + if git.stdout: + git.stdout.close() + tar.wait() + git.wait() + v.result(git.returncode == 0 and tar.returncode == 0) + + +def git_get_tarball( + v: Verification, + channel: TarrableSearchPath, + pin: GitPin) -> str: + cache_file = tarball_cache_file(channel, pin) + if os.path.exists(cache_file): + with open(cache_file, encoding='utf-8') as f: + cached_tarball = f.read(9999) + if os.path.exists(cached_tarball): + return cached_tarball + + with tempfile.TemporaryDirectory() as output_dir: + output_filename = os.path.join( + output_dir, pin.release_name + '.tar.xz') + with open(output_filename, 'w', encoding='utf-8') as output_file: + v.status(f'Generating tarball for git revision {pin.git_revision}') + with subprocess.Popen( + ['git', '-C', git_cache.git_cachedir(channel.git_repo), + 'archive', f'--prefix={pin.release_name}/', pin.git_revision], + stdout=subprocess.PIPE) as git: + with subprocess.Popen(['xz'], stdin=git.stdout, stdout=output_file) as xz: + xz.wait() + git.wait() + v.result(git.returncode == 0 and xz.returncode == 0) + + store_tarball = copy_to_nix_store(v, output_filename) + + os.makedirs(os.path.dirname(cache_file), exist_ok=True) + with open(cache_file, 'w', encoding='utf-8') as f: + f.write(store_tarball) + return store_tarball # type: ignore # (for old mypy) + + +def check_channel_metadata( + v: Verification, + pin: GitPin, + channel_contents: str) -> None: + v.status('Verifying git commit in channel tarball') + with open(os.path.join(channel_contents, pin.release_name, '.git-revision'), + encoding='utf-8') as f: + v.result(f.read(999) == pin.git_revision) + + v.status( + f'Verifying version-suffix is a suffix of release name {pin.release_name}:') + with open(os.path.join(channel_contents, pin.release_name, '.version-suffix'), + encoding='utf-8') as f: + version_suffix = f.read(999) + v.status(version_suffix) + v.result(pin.release_name.endswith(version_suffix)) + + +def check_channel_contents( + v: Verification, + channel: TarrableSearchPath, + table: Dict[str, ChannelTableEntry], + pin: GitPin) -> None: + with tempfile.TemporaryDirectory() as channel_contents, \ + tempfile.TemporaryDirectory() as git_contents: + + extract_tarball(v, table, channel_contents) + check_channel_metadata(v, pin, channel_contents) + + git_checkout(v, channel, pin, git_contents) + + compare_tarball_and_git(v, pin, channel_contents, git_contents) + + v.status('Removing temporary directories') + v.ok() + + +def git_revision_name( + v: Verification, + channel: TarrableSearchPath, + git_revision: str) -> str: + v.status('Getting commit date') + process = subprocess.run(['git', + '-C', + git_cache.git_cachedir(channel.git_repo), + 'log', + '-n1', + '--format=%ct-%h', + '--abbrev=11', + '--no-show-signature', + git_revision], + stdout=subprocess.PIPE) + v.result(process.returncode == 0 and process.stdout != b'') + return f'{os.path.basename(channel.git_repo)}-{process.stdout.decode().strip()}' + + +K = TypeVar('K') +V = TypeVar('V') + + +def partition_dict(pred: Callable[[K, V], bool], + d: Dict[K, V]) -> Tuple[Dict[K, V], Dict[K, V]]: + selected: Dict[K, V] = {} + remaining: Dict[K, V] = {} + for k, v in d.items(): + if pred(k, v): + selected[k] = v + else: + remaining[k] = v + return selected, remaining + + +def filter_dict(d: Dict[K, V], fields: Set[K] + ) -> Tuple[Dict[K, V], Dict[K, V]]: + return partition_dict(lambda k, v: k in fields, d) + + +def read_config_section( + conf: configparser.SectionProxy) -> Tuple[SearchPath, Optional[Pin]]: + mapping: Mapping[str, Tuple[Type[SearchPath], Type[Pin]]] = { + 'alias': (AliasSearchPath, AliasPin), + 'channel': (ChannelSearchPath, ChannelPin), + 'git': (GitSearchPath, GitPin), + 'symlink': (SymlinkSearchPath, SymlinkPin), + } + SP, P = mapping[conf['type']] + _, all_fields = filter_dict(dict(conf.items()), set(['type'])) + pin_fields, remaining_fields = filter_dict(all_fields, set(P._fields)) + # Error suppression works around https://github.com/python/mypy/issues/9007 + pin_present = pin_fields or P._fields == () + pin = P(**pin_fields) if pin_present else None # type: ignore + return SP(**remaining_fields), pin + + +def read_pinned_config_section( + section: str, conf: configparser.SectionProxy) -> Tuple[SearchPath, Pin]: + sp, pin = read_config_section(conf) + if pin is None: + raise RuntimeError( + f'Cannot update unpinned channel "{section}" (Run "pin" before "update")') + return sp, pin + + +def read_config(filename: str) -> configparser.ConfigParser: + config = configparser.ConfigParser() + with open(filename, encoding='utf-8') as f: + config.read_file(f, filename) + return config + + +def read_config_files( + filenames: Iterable[str]) -> Dict[str, configparser.SectionProxy]: + merged_config: Dict[str, configparser.SectionProxy] = {} + for file in filenames: + config = read_config(file) + for section in config.sections(): + if section in merged_config: + raise RuntimeError('Duplicate channel "{section}"') + merged_config[section] = config[section] + return merged_config + + +def pinCommand(args: argparse.Namespace) -> None: v = Verification() - info = fetch(v, 'https://channels.nixos.org/nixos-20.03') - parse_table(v, info) - fetch_resources(v, info) - extract_channel(v, info) - print(info) + config = read_config(args.channels_file) + for section in config.sections(): + if args.channels and section not in args.channels: + continue + + sp, old_pin = read_config_section(config[section]) + config[section].update(sp.pin(v, old_pin)._asdict()) -main() + with open(args.channels_file, 'w', encoding='utf-8') as configfile: + config.write(configfile) + + +def updateCommand(args: argparse.Namespace) -> None: + v = Verification() + exprs: Dict[str, str] = {} + profile_manifest = os.path.join(args.profile, "manifest.nix") + search_paths: List[str] = [ + "-I", "pinch_profile=" + args.profile, + "-I", "pinch_profile_manifest=" + os.readlink(profile_manifest) + ] if os.path.exists(profile_manifest) else [] + config = { + section: read_pinned_config_section(section, conf) for section, + conf in read_config_files( + args.channels_file).items()} + alias, nonalias = partition_dict( + lambda k, v: isinstance(v[0], AliasSearchPath), config) + + for section, (sp, pin) in sorted(nonalias.items()): + assert not isinstance(sp, AliasSearchPath) # mypy can't see through + assert not isinstance(pin, AliasPin) # partition_dict() + tarball = sp.fetch(v, pin) + search_paths.extend( + ["-I", f"pinch_tarball_for_{pin.release_name}={tarball}"]) + exprs[section] = ( + f'f: f {{ name = "{pin.release_name}"; channelName = "%s"; ' + f'src = builtins.storePath "{tarball}"; }}') + + for section, (sp, pin) in alias.items(): + assert isinstance(sp, AliasSearchPath) # For mypy + exprs[section] = exprs[sp.alias_of] + + command = [ + 'nix-env', + '--profile', + args.profile, + '--show-trace', + '--file', + '', + '--install', + '--remove-all', + ] + search_paths + ['--from-expression'] + [ + exprs[name] % name for name in sorted(exprs.keys())] + if args.dry_run: + print(' '.join(map(shlex.quote, command))) + else: + v.status('Installing channels with nix-env') + process = subprocess.run(command) + v.result(process.returncode == 0) + + +def main() -> None: + parser = argparse.ArgumentParser(prog='pinch') + subparsers = parser.add_subparsers(dest='mode', required=True) + parser_pin = subparsers.add_parser('pin') + parser_pin.add_argument('channels_file', type=str) + parser_pin.add_argument('channels', type=str, nargs='*') + parser_pin.set_defaults(func=pinCommand) + parser_update = subparsers.add_parser('update') + parser_update.add_argument('--dry-run', action='store_true') + parser_update.add_argument('--profile', default=( + f'/nix/var/nix/profiles/per-user/{getpass.getuser()}/channels')) + parser_update.add_argument('channels_file', type=str, nargs='+') + parser_update.set_defaults(func=updateCommand) + args = parser.parse_args() + args.func(args) + + +if __name__ == '__main__': + main()