Source code for metadataserver.models.nodeuserdata

# Copyright 2012 Canonical Ltd.  This software is licensed under the
# GNU Affero General Public License version 3 (see the file LICENSE).

"""Node user-data for cloud-init's use."""

from __future__ import (
    absolute_import,
    print_function,
    unicode_literals,
    )

str = None

__metaclass__ = type
__all__ = [
    'NodeUserData',
    ]


from django.db.models import (
    ForeignKey,
    Manager,
    Model,
    )
from maasserver.models.cleansave import CleanSave
from metadataserver import DefaultMeta
from metadataserver.fields import (
    Bin,
    BinaryField,
    )


class NodeUserDataManager(Manager):
    """Utility for the collection of NodeUserData items."""

    def set_user_data(self, node, data):
        """Set user data for the given node.

        If `data` is None, remove user data for the node.
        """
        if data is None:
            self._remove(node)
        else:
            self._set(node, data)

    def get_user_data(self, node):
        """Retrieve user data for the given node."""
        return self.get(node=node).data

    def has_user_data(self, node):
        """Do we have user data registered for node?"""
        return self.filter(node=node).exists()

    def _set(self, node, data):
        """Set actual user data for a node.  Not usable if data is None."""
        wrapped_data = Bin(data)
        (existing_entry, created) = self.get_or_create(
            node=node, defaults={'data': wrapped_data})
        if not created:
            existing_entry.data = wrapped_data
            existing_entry.save()

    def _remove(self, node):
        """Remove metadata from node, if it has any any."""
        self.filter(node=node).delete()


class NodeUserData(CleanSave, Model):
    """User-data portion of a node's metadata.

    When cloud-init sets up a node, it retrieves specific data for that node
    from the metadata service.  One portion of that is the "user-data" binary
    blob.

    :ivar node: Node that this is for.
    :ivar data: base64-encoded data.
    """

    class Meta(DefaultMeta):
        """Needed for South to recognize this model."""

    objects = NodeUserDataManager()

    node = ForeignKey(
        'maasserver.Node', null=False, editable=False, unique=True)
    data = BinaryField(null=False)