cyborg/cyborg/image/api.py

#    Licensed under the Apache License, Version 2.0 (the "License"); you may
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#         http://www.apache.org/licenses/LICENSE-2.0
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"""
Main abstraction layer for retrieving and storing information about acclerator
images used by the cyborg agent layer.
"""

from cyborg.image import glance
from oslo_log import log

LOG = log.getLogger(__name__)


class API(object):

    """Responsible for exposing a relatively stable internal API for other
    modules in Cyborg to retrieve information about acclerator images.
    """

    def _get_session_and_image_id(self, context, id_or_uri):
        """Returns a tuple of (session, image_id). If the supplied `id_or_uri`
        is an image ID, then the default client session will be returned
        for the context's user, along with the image ID. If the supplied
        `id_or_uri` parameter is a URI, then a client session connecting to
        the URI's image service endpoint will be returned along with a
        parsed image ID from that URI.

        :param context: The `cyborg.context.Context` object for the request
        :param id_or_uri: A UUID identifier or an image URI to look up image
                          information for.
        """
        return glance.get_remote_image_service(context, id_or_uri)

    def _get_session(self, _context):
        """Returns a client session that can be used to query for image
        information.

        :param _context: The `cyborg.context.Context` object for the request
        """
        return glance.get_default_image_service()

    @staticmethod
    def generate_image_url(image_ref, context):
        """Generate an image URL from an image_ref.

        :param image_ref: The image ref to generate URL
        :param context: The `cyborg.context.Context` object for the request
        """
        return "%s/images/%s" % (
            glance.get_api_server(context),
            image_ref,
        )

    def get_all(self, context, **kwargs):
        """Retrieves all information records about all acclerator images
        available to show to the requesting user. If the requesting user is an
        admin, all images in an ACTIVE status are returned. If the requesting
        user is not an admin, the all public images and all private images
        that are owned by the requesting user in the ACTIVE status are
        returned.

        :param context: The `cyborg.context.Context` object for the request
        :param kwargs: A dictionary of filter and pagination values that
                       may be passed to the underlying image info driver.
        """
        session = self._get_session(context)
        return session.detail(context, **kwargs)

    def get(self, context, id_or_uri):
        """Retrieves the information record for a single acclerator image.
        If the supplied identifier parameter is a UUID, the default driver will
        be used to return information about the image. If the supplied
        identifier is a URI, then the driver that matches that URI endpoint
        will be used to query for image information.

        :param context: The `cyborg.context.Context` object for the request
        :param id_or_uri: A UUID identifier or an image URI to look up image
                          information for.
        """
        session, image_id = self._get_session_and_image_id(context, id_or_uri)
        return session.show(context, image_id,
                            include_locations=False,
                            show_deleted=False)

    def update(self, context, id_or_uri, image_info,
               data=None, purge_props=False):
        """Update the information about an image, optionally along with a file
        handle or bytestream iterator for image bits. If the optional file
        handle for updated image bits is supplied, the image may not have
        already uploaded bits for the image.

        :param context: The `cyborg.context.Context` object for the request
        :param id_or_uri: A UUID identifier or an image URI to look up image
                          information for.
        :param image_info: A dict of information about the image that is
                           passed to the image registry.
        :param data: Optional file handle or bytestream iterator that is
                     passed to backend storage.
        :param purge_props: Optional, defaults to False. If set, the backend
                            image registry will clear all image properties
                            and replace them the image properties supplied
                            in the image_info dictionary's 'properties'
                            collection.
        """
        session, image_id = self._get_session_and_image_id(context, id_or_uri)
        return session.update(context, image_id, image_info, data=data,
                              purge_props=purge_props)

    def delete(self, context, id_or_uri):
        """Delete the information about an image and mark the image bits for
        deletion.

        :param context: The `cyborg.context.Context` object for the request
        :param id_or_uri: A UUID identifier or an image URI to look up image
                          information for.
        """
        session, image_id = self._get_session_and_image_id(context, id_or_uri)
        return session.delete(context, image_id)

    def download(self, context, id_or_uri, data=None, dest_path=None):
        """Transfer image bits from Glance or a known source location to the
        supplied destination filepath.

        :param context: The `cyborg.context.RequestContext` object for the
                        request
        :param id_or_uri: A UUID identifier or an image URI to look up image
                          information for.
        :param data: A file object to use in downloading image data.
        :param dest_path: Filepath to transfer image bits to.

        Note that because of the poor design of the
        `glance.ImageService.download` method, the function returns different
        things depending on what arguments are passed to it. If a data argument
        is supplied but no dest_path is specified (only done in the XenAPI virt
        driver's image.utils module) then None is returned from the method. If
        the data argument is not specified but a destination path *is*
        specified, then a writeable file handle to the destination path is
        constructed in the method and the image bits written to that file, and
        again, None is returned from the method. If no data argument is
        supplied and no dest_path argument is supplied (VMWare and XenAPI virt
        drivers), then the method returns an iterator to the image bits that
        the caller uses to write to wherever location it wants.

        I think the above points to just how hacky/wacky all of this code is,
        and the reason it needs to be cleaned up and standardized across the
        virt driver callers.
        """

        session, image_id = self._get_session_and_image_id(context, id_or_uri)
        return session.download(context, image_id, data=data,
                                dst_path=dest_path)

    def get_images_by_properties(self, context, properties):
        session = self._get_session(context)
        return session.get_images_by_properties(context, properties)