ah_bootstrap.py

"""
This bootstrap module contains code for ensuring that the astropy_helpers
package will be importable by the time the setup.py script runs.  It also
includes some workarounds to ensure that a recent-enough version of setuptools
is being used for the installation.

This module should be the first thing imported in the setup.py of distributions
that make use of the utilities in astropy_helpers.  If the distribution ships
with its own copy of astropy_helpers, this module will first attempt to import
from the shipped copy.  However, it will also check PyPI to see if there are
any bug-fix releases on top of the current version that may be useful to get
past platform-specific bugs that have been fixed.  When running setup.py, use
the ``--offline`` command-line option to disable the auto-upgrade checks.

When this module is imported or otherwise executed it automatically calls a
main function that attempts to read the project's setup.cfg file, which it
checks for a configuration section called ``[ah_bootstrap]`` the presences of
that section, and options therein, determine the next step taken:  If it
contains an option called ``auto_use`` with a value of ``True``, it will
automatically call the main function of this module called
`use_astropy_helpers` (see that function's docstring for full details).
Otherwise no further action is taken (however,
``ah_bootstrap.use_astropy_helpers`` may be called manually from within the
setup.py script).

Additional options in the ``[ah_boostrap]`` section of setup.cfg have the same
names as the arguments to `use_astropy_helpers`, and can be used to configure
the bootstrap script when ``auto_use = True``.

See https://github.com/astropy/astropy-helpers for more details, and for the
latest version of this module.
"""

import contextlib
import errno
import imp
import os
import re
import subprocess as sp
import sys

try:
    from ConfigParser import ConfigParser
except ImportError:
    from configparser import ConfigParser


if sys.version_info[0] < 3:
    _str_types = (str, unicode)
else:
    _str_types = (str, bytes)

# Some pre-setuptools checks to ensure that either distribute or setuptools >=
# 0.7 is used (over pre-distribute setuptools) if it is available on the path;
# otherwise the latest setuptools will be downloaded and bootstrapped with
# ``ez_setup.py``.  This used to be included in a separate file called
# setuptools_bootstrap.py; but it was combined into ah_bootstrap.py
try:
    import pkg_resources
    _setuptools_req = pkg_resources.Requirement.parse('setuptools>=0.7')
    # This may raise a DistributionNotFound in which case no version of
    # setuptools or distribute is properly instlaled
    _setuptools = pkg_resources.get_distribution('setuptools')
    if _setuptools not in _setuptools_req:
        # Older version of setuptools; check if we have distribute; again if
        # this results in DistributionNotFound we want to give up
        _distribute = pkg_resources.get_distribution('distribute')
        if _setuptools != _distribute:
            # It's possible on some pathological systems to have an old version
            # of setuptools and distribute on sys.path simultaneously; make
            # sure distribute is the one that's used
            sys.path.insert(1, _distribute.location)
            _distribute.activate()
            imp.reload(pkg_resources)
except:
    # There are several types of exceptions that can occur here; if all else
    # fails bootstrap and use the bootstrapped version
    from ez_setup import use_setuptools
    use_setuptools()

from distutils import log
from distutils.debug import DEBUG

# In case it didn't successfully import before the ez_setup checks
import pkg_resources

from setuptools import Distribution
from setuptools.package_index import PackageIndex
from setuptools.sandbox import run_setup

# TODO: Maybe enable checking for a specific version of astropy_helpers?
DIST_NAME = 'astropy-helpers'
PACKAGE_NAME = 'astropy_helpers'

# Defaults for other options
DOWNLOAD_IF_NEEDED = True
INDEX_URL = 'https://pypi.python.org/simple'
USE_GIT = True
AUTO_UPGRADE = True


def use_astropy_helpers(path=None, download_if_needed=None, index_url=None,
                        use_git=None, auto_upgrade=None):
    """
    Ensure that the `astropy_helpers` module is available and is importable.
    This supports automatic submodule initialization if astropy_helpers is
    included in a project as a git submodule, or will download it from PyPI if
    necessary.

    Parameters
    ----------

    path : str or None, optional
        A filesystem path relative to the root of the project's source code
        that should be added to `sys.path` so that `astropy_helpers` can be
        imported from that path.

        If the path is a git submodule it will automatically be initialzed
        and/or updated.

        The path may also be to a ``.tar.gz`` archive of the astropy_helpers
        source distribution.  In this case the archive is automatically
        unpacked and made temporarily available on `sys.path` as a ``.egg``
        archive.

        If `None` skip straight to downloading.

    download_if_needed : bool, optional
        If the provided filesystem path is not found an attempt will be made to
        download astropy_helpers from PyPI.  It will then be made temporarily
        available on `sys.path` as a ``.egg`` archive (using the
        ``setup_requires`` feature of setuptools.  If the ``--offline`` option
        is given at the command line the value of this argument is overridden
        to `False`.

    index_url : str, optional
        If provided, use a different URL for the Python package index than the
        main PyPI server.

    use_git : bool, optional
        If `False` no git commands will be used--this effectively disables
        support for git submodules. If the ``--no-git`` option is given at the
        command line the value of this argument is overridden to `False`.

    auto_upgrade : bool, optional
        By default, when installing a package from a non-development source
        distribution ah_boostrap will try to automatically check for patch
        releases to astropy-helpers on PyPI and use the patched version over
        any bundled versions.  Setting this to `False` will disable that
        functionality. If the ``--offline`` option is given at the command line
        the value of this argument is overridden to `False`.
    """

    # True by default, unless the --offline option was provided on the command
    # line
    if '--offline' in sys.argv:
        download_if_needed = False
        auto_upgrade = False
        sys.argv.remove('--offline')

    if '--no-git' in sys.argv:
        use_git = False
        sys.argv.remove('--no-git')

    if path is None:
        path = PACKAGE_NAME

    if download_if_needed is None:
        download_if_needed = DOWNLOAD_IF_NEEDED

    if index_url is None:
        index_url = INDEX_URL

    if use_git is None:
        use_git = USE_GIT

    if auto_upgrade is None:
        auto_upgrade = AUTO_UPGRADE

    # Declared as False by default--later we check if astropy-helpers can be
    # upgraded from PyPI, but only if not using a source distribution (as in
    # the case of import from a git submodule)
    is_submodule = False

    if not isinstance(path, _str_types):
        if path is not None:
            raise TypeError('path must be a string or None')

        if not download_if_needed:
            log.debug('a path was not given and download from PyPI was not '
                      'allowed so this is effectively a no-op')
            return
    elif not os.path.exists(path) or os.path.isdir(path):
        # Even if the given path does not exist on the filesystem, if it *is* a
        # submodule, `git submodule init` will create it
        is_submodule = use_git and _check_submodule(path)

        if is_submodule or os.path.isdir(path):
            log.info(
                'Attempting to import astropy_helpers from {0} {1!r}'.format(
                    'submodule' if is_submodule else 'directory', path))
            dist = _directory_import(path)
        else:
            dist = None

        if dist is None:
            msg = (
                'The requested path {0!r} for importing {1} does not '
                'exist, or does not contain a copy of the {1} pacakge.  '
                'Attempting download instead.'.format(path, PACKAGE_NAME))
            if download_if_needed:
                log.warn(msg)
            else:
                raise _AHBootstrapSystemExit(msg)
    elif os.path.isfile(path):
        # Handle importing from a source archive; this also uses setup_requires
        # but points easy_install directly to the source archive
        try:
            dist = _do_download(find_links=[path])
        except Exception as e:
            if download_if_needed:
                log.warn('{0}\nWill attempt to download astropy_helpers from '
                         'PyPI instead.'.format(str(e)))
                dist = None
            else:
                raise _AHBootstrapSystemExit(e.args[0])
    else:
        msg = ('{0!r} is not a valid file or directory (it could be a '
               'symlink?)'.format(path))
        if download_if_needed:
            log.warn(msg)
            dist = None
        else:
            raise _AHBootstrapSystemExit(msg)

    if dist is not None and auto_upgrade and not is_submodule:
        # A version of astropy-helpers was found on the available path, but
        # check to see if a bugfix release is available on PyPI
        upgrade = _do_upgrade(dist, index_url)
        if upgrade is not None:
            dist = upgrade
    elif dist is None:
        # Last resort--go ahead and try to download the latest version from
        # PyPI
        try:
            if download_if_needed:
                log.warn(
                    "Downloading astropy_helpers; run setup.py with the "
                    "--offline option to force offline installation.")
                dist = _do_download(index_url=index_url)
            else:
                raise _AHBootstrapSystemExit(
                    "No source for the astropy_helpers package; "
                    "astropy_helpers must be available as a prerequisite to "
                    "installing this package.")
        except Exception as e:
            if DEBUG:
                raise
            else:
                raise _AHBootstrapSystemExit(e.args[0])

    if dist is not None:
        # Otherwise we found a version of astropy-helpers so we're done
        # Just activate the found distribibution on sys.path--if we did a
        # download this usually happens automatically but do it again just to
        # be sure
        return dist.activate()


def _do_download(version='', find_links=None, index_url=None):
    try:
        if find_links:
            allow_hosts = ''
            index_url = None
        else:
            allow_hosts = None
        # Annoyingly, setuptools will not handle other arguments to
        # Distribution (such as options) before handling setup_requires, so it
        # is not straightfoward to programmatically augment the arguments which
        # are passed to easy_install
        class _Distribution(Distribution):
            def get_option_dict(self, command_name):
                opts = Distribution.get_option_dict(self, command_name)
                if command_name == 'easy_install':
                    if find_links is not None:
                        opts['find_links'] = ('setup script', find_links)
                    if index_url is not None:
                        opts['index_url'] = ('setup script', index_url)
                    if allow_hosts is not None:
                        opts['allow_hosts'] = ('setup script', allow_hosts)
                return opts

        if version:
            req = '{0}=={1}'.format(DIST_NAME, version)
        else:
            req = DIST_NAME

        attrs = {'setup_requires': [req]}
        if DEBUG:
            dist = _Distribution(attrs=attrs)
        else:
            with _silence():
                dist = _Distribution(attrs=attrs)

        return pkg_resources.working_set.by_key.get(DIST_NAME)
    except Exception as e:
        if DEBUG:
            raise

        msg = 'Error retrieving astropy helpers from {0}:\n{1}'
        if find_links:
            source = find_links[0]
        elif index_url:
            source = index_url
        else:
            source = 'PyPI'

        raise Exception(msg.format(source, repr(e)))


def _do_upgrade(dist, index_url):
    # Build up a requirement for a higher bugfix release but a lower minor
    # release (so API compatibility is guaranteed)
    # sketchy version parsing--maybe come up with something a bit more
    # robust for this
    major, minor = (int(part) for part in dist.parsed_version[:2])
    next_minor = '.'.join([str(major), str(minor + 1), '0'])
    req = pkg_resources.Requirement.parse(
        '{0}>{1},<{2}'.format(DIST_NAME, dist.version, next_minor))

    package_index = PackageIndex(index_url=index_url)

    upgrade = package_index.obtain(req)

    if upgrade is not None:
        return _do_download(version=upgrade.version, index_url=index_url)


def _directory_import(path):
    """
    Import astropy_helpers from the given path, which will be added to
    sys.path.

    Must return True if the import succeeded, and False otherwise.
    """

    # Return True on success, False on failure but download is allowed, and
    # otherwise raise SystemExit
    path = os.path.abspath(path)
    pkg_resources.working_set.add_entry(path)
    dist = pkg_resources.working_set.by_key.get(DIST_NAME)

    if dist is None:
        # We didn't find an egg-info/dist-info in the given path, but if a
        # setup.py exists we can generate it
        setup_py = os.path.join(path, 'setup.py')
        if os.path.isfile(setup_py):
            with _silence():
                run_setup(os.path.join(path, 'setup.py'), ['egg_info'])

            for dist in pkg_resources.find_distributions(path, True):
                # There should be only one...
                pkg_resources.working_set.add(dist, path, False)
                break

    return dist


def _check_submodule(path):
    try:
        p = sp.Popen(['git', 'submodule', 'status', '--', path],
                     stdout=sp.PIPE, stderr=sp.PIPE)
        stdout, stderr = p.communicate()
    except OSError as e:
        if DEBUG:
            raise

        if e.errno == errno.ENOENT:
            # The git command simply wasn't found; this is most likely the
            # case on user systems that don't have git and are simply
            # trying to install the package from PyPI or a source
            # distribution.  Silently ignore this case and simply don't try
            # to use submodules
            return False
        else:
            raise _AHBoostrapSystemExit(
                'An unexpected error occurred when running the '
                '`git submodule status` command:\n{0}'.format(str(e)))


    if p.returncode != 0 or stderr:
        # Unfortunately the return code alone cannot be relied on, as
        # earler versions of git returned 0 even if the requested submodule
        # does not exist
        log.debug('git submodule command failed '
                  'unexpectedly:\n{0}'.format(stderr))
        return False
    else:
        # The stdout should only contain one line--the status of the
        # requested submodule
        m = _git_submodule_status_re.match(stdout)
        if m:
            # Yes, the path *is* a git submodule
            _update_submodule(m.group('submodule'), m.group('status'))
            return True
        else:
            log.warn(
                'Unexected output from `git submodule status`:\n{0}\n'
                'Will attempt import from {1!r} regardless.'.format(
                    stdout, path))
            return False


def _update_submodule(submodule, status):
    if status == b' ':
        # The submodule is up to date; no action necessary
        return
    elif status == b'-':
        cmd = ['update', '--init']
        log.warn('Initializing submodule {0!r}'.format(submodule))
    elif status == b'+':
        cmd = ['update']
        log.warn('Updating submodule {0!r}'.format(submodule))
    elif status == b'U':
        raise _AHBoostrapSystemExit(
            'Error: Submodule {0} contains unresolved merge conflicts.  '
            'Please complete or abandon any changes in the submodule so that '
            'it is in a usable state, then try again.'.format(submodule))
    else:
        log.warn('Unknown status {0!r} for git submodule {1!r}.  Will '
                 'attempt to use the submodule as-is, but try to ensure '
                 'that the submodule is in a clean state and contains no '
                 'conflicts or errors.\n{2}'.format(status, submodule,
                                                    _err_help_msg))
        return

    err_msg = None

    try:
        p = sp.Popen(['git', 'submodule'] + cmd + ['--', submodule],
                     stdout=sp.PIPE, stderr=sp.PIPE)
        stdout, stderr = p.communicate()
    except OSError as e:
        err_msg = str(e)
    else:
        if p.returncode != 0:
            err_msg = stderr

    if err_msg:
        log.warn('An unexpected error occurred updating the git submodule '
                 '{0!r}:\n{1}\n{2}'.format(submodule, err_msg, _err_help_msg))


class _DummyFile(object):
    """A noop writeable object."""

    errors = ''  # Required for Python 3.x

    def write(self, s):
        pass

    def flush(self):
        pass


@contextlib.contextmanager
def _silence():
    """A context manager that silences sys.stdout and sys.stderr."""

    old_stdout = sys.stdout
    old_stderr = sys.stderr
    sys.stdout = _DummyFile()
    sys.stderr = _DummyFile()
    exception_occurred = False
    try:
        yield
    except:
        exception_occurred = True
        # Go ahead and clean up so that exception handling can work normally
        sys.stdout = old_stdout
        sys.stderr = old_stderr
        raise

    if not exception_occurred:
        sys.stdout = old_stdout
        sys.stderr = old_stderr


_err_help_msg = """
If the problem persists consider installing astropy_helpers manually using pip
(`pip install astropy_helpers`) or by manually downloading the source archive,
extracting it, and installing by running `python setup.py install` from the
root of the extracted source code.
"""


class _AHBootstrapSystemExit(SystemExit):
    def __init__(self, *args):
        if not args:
            msg = 'An unknown problem occurred bootstrapping astropy_helpers.'
        else:
            msg = args[0]

        msg += '\n' + _err_help_msg

        super(_AHBootstrapSystemExit, self).__init__(msg, *args[1:])


# Output of `git submodule status` is as follows:
#
# 1: Status indicator: '-' for submodule is uninitialized, '+' if submodule is
# initialized but is not at the commit currently indicated in .gitmodules (and
# thus needs to be updated), or 'U' if the submodule is in an unstable state
# (i.e. has merge conflicts)
#
# 2. SHA-1 hash of the current commit of the submodule (we don't really need
# this information but it's useful for checking that the output is correct)
#
# 3. The output of `git describe` for the submodule's current commit hash (this
# includes for example what branches the commit is on) but only if the
# submodule is initialized.  We ignore this information for now
_git_submodule_status_re = re.compile(
    b'^(?P<status>[+-U ])(?P<commit>[0-9a-f]{40}) (?P<submodule>\S+)( .*)?$')


# Implement the auto-use feature; this allows use_astropy_helpers() to be used
# at import-time automatically so long as the correct options are specified in
# setup.cfg
_CFG_OPTIONS = [('auto_use', bool), ('path', str),
                ('download_if_needed', bool), ('index_ur', str),
                ('use_git', bool), ('auto_upgrade', bool)]

def _main():
    if not os.path.exists('setup.cfg'):
        return

    cfg = ConfigParser()

    try:
        cfg.read('setup.cfg')
    except Exception as e:
        if DEBUG:
            raise

        log.error(
            "Error reading setup.cfg: {0!r}\nastropy_helpers will not be "
            "automatically bootstrapped and package installation may fail."
            "\n{1}".format(e, _err_help_msg))
        return

    if not cfg.has_section('ah_bootstrap'):
        return

    kwargs = {}

    for option, type_ in _CFG_OPTIONS:
        if not cfg.has_option('ah_bootstrap', option):
            continue

        if type_ is bool:
            value = cfg.getboolean('ah_bootstrap', option)
        else:
            value = cfg.get('ah_bootstrap', option)

        kwargs[option] = value

    if kwargs.pop('auto_use', False):
        use_astropy_helpers(**kwargs)


_main()