Synnefo » snf-image-creator

# -*- coding: utf-8 -*-

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"""This package provides various classes for preparing different Operating

Systems for image creation.

"""

from image_creator.util import FatalError

import textwrap

import re

from collections import namedtuple

from functools import wraps

def os_cls(distro, osfamily):

    """Given the distro name and the osfamily, return the appropriate class"""

    module = None

    classname = None

    try:

        module = __import__("image_creator.os_type.%s" % distro,

                            fromlist=['image_creator.os_type'])

        classname = distro.capitalize()

    except ImportError:

        module = __import__("image_creator.os_type.%s" % osfamily,

                            fromlist=['image_creator.os_type'])

        classname = osfamily.capitalize()

    return getattr(module, classname)

def add_prefix(target):

    def wrapper(self, *args):

        prefix = args[0]

        return [prefix + path for path in target(self, *args)]

    return wrapper

def sysprep(message, enabled=True, **kwargs):

    """Decorator for system preparation tasks"""

    def wrapper(method):

        method.sysprep = True

        method.enabled = enabled

        method.executed = False

        for key, val in kwargs.items():

            setattr(method, key, val)

        @wraps(method)

        def inner(self, print_message=True):

            if print_message:

                self.out.output(message)

            return method(self)

        return inner

    return wrapper

def add_sysprep_param(name, type, default, descr, validate=lambda x: True):

    """Decorator for __init__ that adds the definition for a system preparation

    parameter in an instance of a os_type class

    """

    def wrapper(init):

        @wraps(init)

        def inner(self, *args, **kwargs):

            init(self, *args, **kwargs)

            self.needed_sysprep_params[name] = \

                self.SysprepParam(type, default, descr, validate)

        return inner

    return wrapper

def del_sysprep_param(name):

    """Decorator for __init__ that deletes a previously added sysprep parameter

    definition from an instance of a os_type class.

    """

    def wrapper(func):

        @wraps(func)

        def inner(self, *args, **kwargs):

            del self.needed_sysprep_params[name]

            func(self, *args, **kwargs)

        return inner

    return wrapper

class OSBase(object):

    """Basic operating system class"""

    SysprepParam = namedtuple('SysprepParam',

                              ['type', 'default', 'description', 'validate'])

    def __init__(self, image, **kargs):

        self.image = image

        self.root = image.root

        self.g = image.g

        self.out = image.out

        self.needed_sysprep_params = {}

        self.sysprep_params = \

            kargs['sysprep_params'] if 'sysprep_params' in kargs else {}

        self.meta = {}

        self.mounted = False

    def collect_metadata(self):

        """Collect metadata about the OS"""

        try:

            if not self.mount(readonly=True):

                raise FatalError("Unable to mount the media read-only")

            self.out.output('Collecting image metadata ...', False)

            self._do_collect_metadata()

            self.out.success('done')

        finally:

            self.umount()

        self.out.output()

    def list_syspreps(self):

        """Returns a list of sysprep objects"""

        objs = [getattr(self, name) for name in dir(self)

                if not name.startswith('_')]

        return [x for x in objs if self._is_sysprep(x) and x.executed is False]

    def sysprep_info(self, obj):

        """Returns information about a sysprep object"""

        assert self._is_sysprep(obj), "Object is not a sysprep"

        SysprepInfo = namedtuple("SysprepInfo", "name description")

        return SysprepInfo(obj.__name__.replace('_', '-'),

                           textwrap.dedent(obj.__doc__))

    def get_sysprep_by_name(self, name):

        """Returns the sysprep object with the given name"""

        error_msg = "Syprep operation %s does not exist for %s" % \

                    (name, self.__class__.__name__)

        method_name = name.replace('-', '_')

        method = None

        try:

            method = getattr(self, method_name)

        except AttributeError:

            raise FatalError(error_msg)

        if not self._is_sysprep(method):

            raise FatalError(error_msg)

        return method

    def enable_sysprep(self, obj):

        """Enable a system preparation operation"""

        setattr(obj.im_func, 'enabled', True)

    def disable_sysprep(self, obj):

        """Disable a system preparation operation"""

        setattr(obj.im_func, 'enabled', False)

    def print_syspreps(self):

        """Print enabled and disabled system preparation operations."""

        syspreps = self.list_syspreps()

        enabled = [sysprep for sysprep in syspreps if sysprep.enabled]

        disabled = [sysprep for sysprep in syspreps if not sysprep.enabled]

        wrapper = textwrap.TextWrapper()

        wrapper.subsequent_indent = '\t'

        wrapper.initial_indent = '\t'

        wrapper.width = 72

        self.out.output("Enabled system preparation operations:")

        if len(enabled) == 0:

            self.out.output("(none)")

        else:

            for sysprep in enabled:

                name = sysprep.__name__.replace('_', '-')

                descr = wrapper.fill(textwrap.dedent(sysprep.__doc__))

                self.out.output('    %s:\n%s\n' % (name, descr))

        self.out.output("Disabled system preparation operations:")

        if len(disabled) == 0:

            self.out.output("(none)")

        else:

            for sysprep in disabled:

                name = sysprep.__name__.replace('_', '-')

                descr = wrapper.fill(textwrap.dedent(sysprep.__doc__))

                self.out.output('    %s:\n%s\n' % (name, descr))

    def print_sysprep_params(self):

        """Print the system preparation parameter the user may use"""

        self.out.output("Needed system preparation parameters:")

        if len(self.needed_sysprep_params) == 0:

            self.out.output("(none)")

            return

        for name, param in self.needed_sysprep_params.items():

            self.out.output("\t%s (%s): %s" %

                            (param.description, name,

                             self.sysprep_params[name] if name in

                             self.sysprep_params else "(none)"))

    def do_sysprep(self):

        """Prepare system for image creation."""

        try:

            if not self.mount(readonly=False):

                raise FatalError("Unable to mount the media read-write")

            self.out.output('Preparing system for image creation:')

            enabled = [task for task in self.list_syspreps() if task.enabled]

            size = len(enabled)

            cnt = 0

            for task in enabled:

                cnt += 1

                self.out.output(('(%d/%d)' % (cnt, size)).ljust(7), False)

                task()

                setattr(task.im_func, 'executed', True)

        finally:

            self.umount()

        self.out.output()

    def mount(self, readonly=False):

        """Mount image."""

        if getattr(self, "mounted", False):

            return True

        mount_type = 'read-only' if readonly else 'read-write'

        self.out.output("Mounting the media %s ..." % mount_type, False)

        if not self._do_mount(readonly):

            return False

        self.mounted = True

        self.out.success('done')

        return True

    def umount(self):

        """Umount all mounted filesystems."""

        self.out.output("Umounting the media ...", False)

        self.g.umount_all()

        self.mounted = False

        self.out.success('done')

    def _is_sysprep(self, obj):

        """Checks if an object is a sysprep"""

        return getattr(obj, 'sysprep', False) and callable(obj)

    @add_prefix

    def _ls(self, directory):

        """List the name of all files under a directory"""

        return self.g.ls(directory)

    @add_prefix

    def _find(self, directory):

        """List the name of all files recursively under a directory"""

        return self.g.find(directory)

    def _foreach_file(self, directory, action, **kargs):

        """Perform an action recursively on all files under a directory.

        The following options are allowed:

        * maxdepth: If defined the action will not be performed on

          files that are below this level of directories under the

          directory parameter.

        * ftype: The action will only be performed on files of this

          type. For a list of all allowed filetypes, see here:

          http://libguestfs.org/guestfs.3.html#guestfs_readdir

        * exclude: Exclude all files that follow this pattern.

        """

        maxdepth = None if 'maxdepth' not in kargs else kargs['maxdepth']

        if maxdepth == 0:

            return

        # maxdepth -= 1

        maxdepth = None if maxdepth is None else maxdepth - 1

        kargs['maxdepth'] = maxdepth

        exclude = None if 'exclude' not in kargs else kargs['exclude']

        ftype = None if 'ftype' not in kargs else kargs['ftype']

        has_ftype = lambda x, y: y is None and True or x['ftyp'] == y

        for f in self.g.readdir(directory):

            if f['name'] in ('.', '..'):

                continue

            full_path = "%s/%s" % (directory, f['name'])

            if exclude and re.match(exclude, full_path):

                continue

            if has_ftype(f, 'd'):

                self._foreach_file(full_path, action, **kargs)

            if has_ftype(f, ftype):

                action(full_path)

    def _do_collect_metadata(self):

        """helper method for collect_metadata"""

        self.meta['ROOT_PARTITION'] = "%d" % self.g.part_to_partnum(self.root)

        self.meta['OSFAMILY'] = self.g.inspect_get_type(self.root)

        self.meta['OS'] = self.g.inspect_get_distro(self.root)

        if self.meta['OS'] == "unknown":

            self.meta['OS'] = self.meta['OSFAMILY']

        self.meta['DESCRIPTION'] = self.g.inspect_get_product_name(self.root)

    def _do_mount(self, readonly):

        """helper method for mount"""

        try:

            self.g.mount_options('ro' if readonly else 'rw', self.root, '/')

        except RuntimeError as msg:

            self.out.warn("unable to mount the root partition: %s" % msg)

            return False

        return True

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