buildPython*: add updateScript to passthru

All Python packages now have an updateScript. The script calls
`update-python-libraries` and passes it the position of the derivation
expression obtained using `meta.position`. This works fine in case a Nix
expression represents only a single derivation. If there are more in it,
`update-python-libraries` will fail.

4 files changed, 392 insertions, 3 deletions

diff --git a/pkgs/development/interpreters/python/build-python-package.nix b/pkgs/development/interpreters/python/build-python-package.nix
index b55d6d874bb..391086a662e 100644
--- a/pkgs/development/interpreters/python/build-python-package.nix
+++ b/pkgs/development/interpreters/python/build-python-package.nix
@@ -12,6 +12,8 @@
 , namePrefix
 , bootstrapped-pip
 , flit
+, writeScript
+, update-python-libraries
 }:
 
 let
@@ -20,7 +22,8 @@ let
   wheel-specific = import ./build-python-package-wheel.nix { };
   common = import ./build-python-package-common.nix { inherit python bootstrapped-pip; };
   mkPythonDerivation = import ./mk-python-derivation.nix {
-    inherit lib config python wrapPython setuptools unzip ensureNewerSourcesForZipFilesHook toPythonModule namePrefix;
+    inherit lib config python wrapPython setuptools unzip ensureNewerSourcesForZipFilesHook;
+    inherit toPythonModule namePrefix writeScript update-python-libraries;
   };
 in
 
diff --git a/pkgs/development/interpreters/python/mk-python-derivation.nix b/pkgs/development/interpreters/python/mk-python-derivation.nix
index 63ffdbb8c0a..eb913e1a375 100644
--- a/pkgs/development/interpreters/python/mk-python-derivation.nix
+++ b/pkgs/development/interpreters/python/mk-python-derivation.nix
@@ -10,6 +10,8 @@
 # Whether the derivation provides a Python module or not.
 , toPythonModule
 , namePrefix
+, writeScript
+, update-python-libraries
 }:
 
 { name ? "${attrs.pname}-${attrs.version}"
@@ -64,7 +66,7 @@ if disabled
 then throw "${name} not supported for interpreter ${python.executable}"
 else
 
-toPythonModule (python.stdenv.mkDerivation (builtins.removeAttrs attrs [
+let self = toPythonModule (python.stdenv.mkDerivation (builtins.removeAttrs attrs [
     "disabled" "checkInputs" "doCheck" "doInstallCheck" "dontWrapPythonPrograms" "catchConflicts"
   ] // {
 
@@ -106,4 +108,14 @@ toPythonModule (python.stdenv.mkDerivation (builtins.removeAttrs attrs [
     platforms = python.meta.platforms;
     isBuildPythonPackage = python.meta.platforms;
   } // meta;
-}))
+}));
+
+passthru = {
+  updateScript = let
+    filename = builtins.head (lib.splitString ":" self.meta.position);
+  in writeScript "update-python" ''
+    #!${python.stdenv.shell}
+    ${update-python-libraries} ${filename}
+  '';
+};
+in lib.extendDerivation true passthru self
diff --git a/pkgs/development/interpreters/python/update-python-libraries/default.nix b/pkgs/development/interpreters/python/update-python-libraries/default.nix
new file mode 100644
index 00000000000..762ca2bdd34
--- /dev/null
+++ b/pkgs/development/interpreters/python/update-python-libraries/default.nix
@@ -0,0 +1,12 @@
+{ python3, runCommand, git }:
+
+runCommand "update-python-libraries" {
+  buildInputs = [
+    (python3.withPackages(ps: with ps; [ packaging requests toolz ]))
+    git
+  ];
+} ''
+  cp ${./update-python-libraries.py} $out
+  patchShebangs $out
+  substituteInPlace $out --replace 'GIT = "git"' 'GIT = "${git}/bin/git"'
+''
\ No newline at end of file
diff --git a/pkgs/development/interpreters/python/update-python-libraries/update-python-libraries.py b/pkgs/development/interpreters/python/update-python-libraries/update-python-libraries.py
new file mode 100755
index 00000000000..9292a930703
--- /dev/null
+++ b/pkgs/development/interpreters/python/update-python-libraries/update-python-libraries.py
@@ -0,0 +1,362 @@
+#!/usr/bin/env python3
+
+"""
+Update a Python package expression by passing in the `.nix` file, or the directory containing it.
+You can pass in multiple files or paths.
+
+You'll likely want to use
+``
+  $ ./update-python-libraries ../../pkgs/development/python-modules/*
+``
+to update all libraries in that folder.
+"""
+
+import argparse
+import logging
+import os
+import re
+import requests
+import toolz
+from concurrent.futures import ThreadPoolExecutor as Pool
+from packaging.version import Version as _Version
+from packaging.version import InvalidVersion
+from packaging.specifiers import SpecifierSet
+import collections
+import subprocess
+
+INDEX = "https://pypi.io/pypi"
+"""url of PyPI"""
+
+EXTENSIONS = ['tar.gz', 'tar.bz2', 'tar', 'zip', '.whl']
+"""Permitted file extensions. These are evaluated from left to right and the first occurance is returned."""
+
+PRERELEASES = False
+
+GIT = "git"
+
+import logging
+logging.basicConfig(level=logging.INFO)
+
+
+class Version(_Version, collections.abc.Sequence):
+
+    def __init__(self, version):
+        super().__init__(version)
+        # We cannot use `str(Version(0.04.21))` because that becomes `0.4.21`
+        # https://github.com/avian2/unidecode/issues/13#issuecomment-354538882
+        self.raw_version = version
+
+    def __getitem__(self, i):
+        return self._version.release[i]
+
+    def __len__(self):
+        return len(self._version.release)
+
+    def __iter__(self):
+        yield from self._version.release
+
+
+def _get_values(attribute, text):
+    """Match attribute in text and return all matches.
+
+    :returns: List of matches.
+    """
+    regex = '{}\s+=\s+"(.*)";'.format(attribute)
+    regex = re.compile(regex)
+    values = regex.findall(text)
+    return values
+
+def _get_unique_value(attribute, text):
+    """Match attribute in text and return unique match.
+
+    :returns: Single match.
+    """
+    values = _get_values(attribute, text)
+    n = len(values)
+    if n > 1:
+        raise ValueError("found too many values for {}".format(attribute))
+    elif n == 1:
+        return values[0]
+    else:
+        raise ValueError("no value found for {}".format(attribute))
+
+def _get_line_and_value(attribute, text):
+    """Match attribute in text. Return the line and the value of the attribute."""
+    regex = '({}\s+=\s+"(.*)";)'.format(attribute)
+    regex = re.compile(regex)
+    value = regex.findall(text)
+    n = len(value)
+    if n > 1:
+        raise ValueError("found too many values for {}".format(attribute))
+    elif n == 1:
+        return value[0]
+    else:
+        raise ValueError("no value found for {}".format(attribute))
+
+
+def _replace_value(attribute, value, text):
+    """Search and replace value of attribute in text."""
+    old_line, old_value = _get_line_and_value(attribute, text)
+    new_line = old_line.replace(old_value, value)
+    new_text = text.replace(old_line, new_line)
+    return new_text
+
+def _fetch_page(url):
+    r = requests.get(url)
+    if r.status_code == requests.codes.ok:
+        return r.json()
+    else:
+        raise ValueError("request for {} failed".format(url))
+
+
+SEMVER = {
+    'major' : 0,
+    'minor' : 1,
+    'patch' : 2,
+}
+
+
+def _determine_latest_version(current_version, target, versions):
+    """Determine latest version, given `target`.
+    """
+    current_version = Version(current_version)
+
+    def _parse_versions(versions):
+        for v in versions:
+            try:
+                yield Version(v)
+            except InvalidVersion:
+                pass
+
+    versions = _parse_versions(versions)
+
+    index = SEMVER[target]
+
+    ceiling = list(current_version[0:index])
+    if len(ceiling) == 0:
+        ceiling = None
+    else:
+        ceiling[-1]+=1
+        ceiling = Version(".".join(map(str, ceiling)))
+
+    # We do not want prereleases
+    versions = SpecifierSet(prereleases=PRERELEASES).filter(versions)
+
+    if ceiling is not None:
+        versions = SpecifierSet(f"<{ceiling}").filter(versions)
+
+    return (max(sorted(versions))).raw_version
+
+
+def _get_latest_version_pypi(package, extension, current_version, target):
+    """Get latest version and hash from PyPI."""
+    url = "{}/{}/json".format(INDEX, package)
+    json = _fetch_page(url)
+
+    versions = json['releases'].keys()
+    version = _determine_latest_version(current_version, target, versions)
+
+    try:
+        releases = json['releases'][version]
+    except KeyError as e:
+        raise KeyError('Could not find version {} for {}'.format(version, package)) from e
+    for release in releases:
+        if release['filename'].endswith(extension):
+            # TODO: In case of wheel we need to do further checks!
+            sha256 = release['digests']['sha256']
+            break
+    else:
+        sha256 = None
+    return version, sha256
+
+
+def _get_latest_version_github(package, extension, current_version, target):
+    raise ValueError("updating from GitHub is not yet supported.")
+
+
+FETCHERS = {
+    'fetchFromGitHub'   :   _get_latest_version_github,
+    'fetchPypi'         :   _get_latest_version_pypi,
+    'fetchurl'          :   _get_latest_version_pypi,
+}
+
+
+DEFAULT_SETUPTOOLS_EXTENSION = 'tar.gz'
+
+
+FORMATS = {
+    'setuptools'        :   DEFAULT_SETUPTOOLS_EXTENSION,
+    'wheel'             :   'whl'
+}
+
+def _determine_fetcher(text):
+    # Count occurences of fetchers.
+    nfetchers = sum(text.count('src = {}'.format(fetcher)) for fetcher in FETCHERS.keys())
+    if nfetchers == 0:
+        raise ValueError("no fetcher.")
+    elif nfetchers > 1:
+        raise ValueError("multiple fetchers.")
+    else:
+        # Then we check which fetcher to use.
+        for fetcher in FETCHERS.keys():
+            if 'src = {}'.format(fetcher) in text:
+                return fetcher
+
+
+def _determine_extension(text, fetcher):
+    """Determine what extension is used in the expression.
+
+    If we use:
+    - fetchPypi, we check if format is specified.
+    - fetchurl, we determine the extension from the url.
+    - fetchFromGitHub we simply use `.tar.gz`.
+    """
+    if fetcher == 'fetchPypi':
+        try:
+            src_format = _get_unique_value('format', text)
+        except ValueError as e:
+            src_format = None   # format was not given
+
+        try:
+            extension = _get_unique_value('extension', text)
+        except ValueError as e:
+            extension = None    # extension was not given
+
+        if extension is None:
+            if src_format is None:
+                src_format = 'setuptools'
+            elif src_format == 'flit':
+                raise ValueError("Don't know how to update a Flit package.")
+            extension = FORMATS[src_format]
+
+    elif fetcher == 'fetchurl':
+        url = _get_unique_value('url', text)
+        extension = os.path.splitext(url)[1]
+        if 'pypi' not in url:
+            raise ValueError('url does not point to PyPI.')
+
+    elif fetcher == 'fetchFromGitHub':
+        raise ValueError('updating from GitHub is not yet implemented.')
+
+    return extension
+
+
+def _update_package(path, target):
+
+    # Read the expression
+    with open(path, 'r') as f:
+        text = f.read()
+
+    # Determine pname.
+    pname = _get_unique_value('pname', text)
+
+    # Determine version.
+    version = _get_unique_value('version', text)
+
+    # First we check how many fetchers are mentioned.
+    fetcher = _determine_fetcher(text)
+
+    extension = _determine_extension(text, fetcher)
+
+    new_version, new_sha256 = FETCHERS[fetcher](pname, extension, version, target)
+
+    if new_version == version:
+        logging.info("Path {}: no update available for {}.".format(path, pname))
+        return False
+    elif Version(new_version) <= Version(version):
+        raise ValueError("downgrade for {}.".format(pname))
+    if not new_sha256:
+        raise ValueError("no file available for {}.".format(pname))
+
+    text = _replace_value('version', new_version, text)
+    text = _replace_value('sha256', new_sha256, text)
+
+    with open(path, 'w') as f:
+        f.write(text)
+
+        logging.info("Path {}: updated {} from {} to {}".format(path, pname, version, new_version))
+
+    result = {
+        'path'  : path,
+        'target': target,
+        'pname': pname,
+        'old_version'   : version,
+        'new_version'   : new_version,
+        #'fetcher'       : fetcher,
+        }
+
+    return result
+
+
+def _update(path, target):
+
+    # We need to read and modify a Nix expression.
+    if os.path.isdir(path):
+        path = os.path.join(path, 'default.nix')
+
+    # If a default.nix does not exist, we quit.
+    if not os.path.isfile(path):
+        logging.info("Path {}: does not exist.".format(path))
+        return False
+
+    # If file is not a Nix expression, we quit.
+    if not path.endswith(".nix"):
+        logging.info("Path {}: does not end with `.nix`.".format(path))
+        return False
+
+    try:
+        return _update_package(path, target)
+    except ValueError as e:
+        logging.warning("Path {}: {}".format(path, e))
+        return False
+
+
+def _commit(path, pname, old_version, new_version, **kwargs):
+    """Commit result.
+    """
+
+    msg = f'python: {pname}: {old_version} -> {new_version}'
+
+    try:
+        subprocess.check_call([GIT, 'add', path])
+        subprocess.check_call([GIT, 'commit', '-m', msg])
+    except subprocess.CalledProcessError as e:
+        subprocess.check_call([GIT, 'checkout', path])
+        raise subprocess.CalledProcessError(f'Could not commit {path}') from e
+
+    return True
+
+
+def main():
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('package', type=str, nargs='+')
+    parser.add_argument('--target', type=str, choices=SEMVER.keys(), default='major')
+    parser.add_argument('--commit', action='store_true', help='Create a commit for each package update')
+
+    args = parser.parse_args()
+    target = args.target
+
+    packages = list(map(os.path.abspath, args.package))
+
+    logging.info("Updating packages...")
+
+    # Use threads to update packages concurrently
+    with Pool() as p:
+        results = list(p.map(lambda pkg: _update(pkg, target), packages))
+
+    logging.info("Finished updating packages.")
+
+    # Commits are created sequentially.
+    if args.commit:
+        logging.info("Committing updates...")
+        list(map(lambda x: _commit(**x), filter(bool, results)))
+        logging.info("Finished committing updates")
+
+    count = sum(map(bool, results))
+    logging.info("{} package(s) updated".format(count))
+
+
+
+if __name__ == '__main__':
+    main()
\ No newline at end of file