Strict image isolation for Nova - Mitaka

aggregate_image_os_type_isolation.py

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#    Licensed under the Apache License, Version 2.0 (the "License"); you may
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#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
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from oslo_config import cfg
from oslo_log import log as logging

from nova.scheduler import filters
from nova.scheduler.filters import utils

isolated_opts = [
    cfg.ListOpt('isolated_image_os_type',
                default=[],
                help='Image os_type to run on isolated host'),
]
CONF = cfg.CONF
CONF.register_opts(isolated_opts)

LOG = logging.getLogger(__name__)


class AggregateImageOsTypeIsolationFilter(filters.BaseHostFilter):
    """Filter compute nodes that satisfy instance image os_type property.

    The AggregateImageOsTypeIsolationFilter filters compute nodes that satisfy
    the os_type property specified on the instance's image properties.
    Image properties are contained in the image dictionary in the request_spec.
    """

    # Aggregate data and Image Properties do not change within a request
    run_filter_once_per_request = True

    def host_passes(self, host_state, spec_obj):
        """Check if host passes specified os_type image property.

        Returns True for compute nodes that satisfy image properties
        contained in the request_spec.
        """

        image_props = spec_obj.image.properties if spec_obj.image else {}
        image_os_type = image_props.get('os_type')

        metadata = utils.aggregate_metadata_get_by_host(host_state)
        host_os_type = metadata.get('os_type')

        # If host has os_type part of its aggregate metadatas, it is reserved
        # for images with the matching os_type property.
        if host_os_type:
            return image_os_type in host_os_type
        else:
            # Host without os_type can only run images not in the list of
            # isolated os_type.
            return image_os_type not in CONF.isolated_image_os_type