# Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or # implied. # See the License for the specific language governing permissions and # limitations under the License. """Cache for nodes currently under introspection.""" import collections import contextlib import copy import datetime import json from automaton import exceptions as automaton_errors from ironicclient import exceptions from oslo_concurrency import lockutils from oslo_config import cfg from oslo_db.sqlalchemy import utils as db_utils from oslo_utils import excutils from oslo_utils import reflection from oslo_utils import timeutils from oslo_utils import uuidutils import six from sqlalchemy.orm import exc as orm_errors from sqlalchemy import text from ironic_inspector.common.i18n import _ from ironic_inspector.common import ironic as ir_utils from ironic_inspector import db from ironic_inspector import introspection_state as istate from ironic_inspector import utils CONF = cfg.CONF LOG = utils.getProcessingLogger(__name__) MACS_ATTRIBUTE = 'mac' _LOCK_TEMPLATE = 'node-%s' _SEMAPHORES = lockutils.Semaphores() def _get_lock(uuid): """Get lock object for a given node UUID.""" return lockutils.internal_lock(_LOCK_TEMPLATE % uuid, semaphores=_SEMAPHORES) def _get_lock_ctx(uuid): """Get context manager yielding a lock object for a given node UUID.""" return lockutils.lock(_LOCK_TEMPLATE % uuid, semaphores=_SEMAPHORES) class NodeInfo(object): """Record about a node in the cache. This class optionally allows to acquire a lock on a node. Note that the class instance itself is NOT thread-safe, you need to create a new instance for every thread. """ def __init__(self, uuid, version_id=None, state=None, started_at=None, finished_at=None, error=None, node=None, ports=None, ironic=None, lock=None): self.uuid = uuid self.started_at = started_at self.finished_at = finished_at self.error = error self.invalidate_cache() self._version_id = version_id self._state = state self._node = node if ports is not None and not isinstance(ports, dict): ports = {p.address: p for p in ports} self._ports = ports self._attributes = None self._ironic = ironic # This is a lock on a node UUID, not on a NodeInfo object self._lock = lock if lock is not None else _get_lock(uuid) # Whether lock was acquired using this NodeInfo object self._locked = lock is not None self._fsm = None def __del__(self): if self._locked: LOG.warning('BUG: node lock was not released by the moment ' 'node info object is deleted') self._lock.release() def __str__(self): """Self represented as an UUID and a state.""" parts = [self.uuid] if self._state: parts += [_('state'), self._state] return ' '.join(parts) def acquire_lock(self, blocking=True): """Acquire a lock on the associated node. Exits with success if a lock is already acquired using this NodeInfo object. :param blocking: if True, wait for lock to be acquired, otherwise return immediately. :returns: boolean value, whether lock was acquired successfully """ if self._locked: return True LOG.debug('Attempting to acquire lock', node_info=self) if self._lock.acquire(blocking): self._locked = True LOG.debug('Successfully acquired lock', node_info=self) return True else: LOG.debug('Unable to acquire lock', node_info=self) return False def release_lock(self): """Release a lock on a node. Does nothing if lock was not acquired using this NodeInfo object. """ if self._locked: LOG.debug('Successfully released lock', node_info=self) self._lock.release() self._locked = False @property def version_id(self): """Get the version id""" if self._version_id is None: row = db.model_query(db.Node).get(self.uuid) if row is None: raise utils.NotFoundInCacheError(_('Node not found in the ' 'cache'), node_info=self) self._version_id = row.version_id return self._version_id def _set_version_id(self, value, session): row = self._row(session) row.version_id = value row.save(session) self._version_id = value def _row(self, session=None): """Get a row from the database with self.uuid and self.version_id""" try: # race condition if version_id changed outside of this node_info return db.model_query(db.Node, session=session).filter_by( uuid=self.uuid, version_id=self.version_id).one() except (orm_errors.NoResultFound, orm_errors.StaleDataError): raise utils.NodeStateRaceCondition(node_info=self) def _commit(self, **fields): """Commit the fields into the DB.""" LOG.debug('Committing fields: %s', fields, node_info=self) with db.ensure_transaction() as session: self._set_version_id(uuidutils.generate_uuid(), session) row = self._row(session) row.update(fields) def commit(self): """Commit current node status into the database.""" # state and version_id are updated separately self._commit(started_at=self.started_at, finished_at=self.finished_at, error=self.error) @property def state(self): """State of the node_info object.""" if self._state is None: row = self._row() self._state = row.state return self._state def _set_state(self, value): self._commit(state=value) self._state = value def _get_fsm(self): """Get an fsm instance initialized with self.state.""" if self._fsm is None: self._fsm = istate.FSM.copy(shallow=True) self._fsm.initialize(start_state=self.state) return self._fsm @contextlib.contextmanager def _fsm_ctx(self): fsm = self._get_fsm() try: yield fsm finally: if fsm.current_state != self.state: LOG.info('Updating node state: %(current)s --> %(new)s', {'current': self.state, 'new': fsm.current_state}, node_info=self) self._set_state(fsm.current_state) def fsm_event(self, event, strict=False): """Update node_info.state based on a fsm.process_event(event) call. An AutomatonException triggers an error event. If strict, node_info.finished(istate.Events.error, error=str(exc)) is called with the AutomatonException instance and a EventError raised. :param event: an event to process by the fsm :strict: whether to fail the introspection upon an invalid event :raises: NodeStateInvalidEvent """ with self._fsm_ctx() as fsm: LOG.debug('Executing fsm(%(state)s).process_event(%(event)s)', {'state': fsm.current_state, 'event': event}, node_info=self) try: fsm.process_event(event) except automaton_errors.NotFound as exc: msg = _('Invalid event: %s') % exc if strict: LOG.error(msg, node_info=self) # assuming an error event is always possible self.finished(istate.Events.error, error=str(exc)) else: LOG.warning(msg, node_info=self) raise utils.NodeStateInvalidEvent(str(exc), node_info=self) @property def options(self): """Node introspection options as a dict.""" if self._options is None: rows = db.model_query(db.Option).filter_by( uuid=self.uuid) self._options = {row.name: json.loads(row.value) for row in rows} return self._options @property def attributes(self): """Node look up attributes as a dict.""" if self._attributes is None: self._attributes = {} rows = db.model_query(db.Attribute).filter_by( node_uuid=self.uuid) for row in rows: self._attributes.setdefault(row.name, []).append(row.value) return self._attributes @property def ironic(self): """Ironic client instance.""" if self._ironic is None: self._ironic = ir_utils.get_client() return self._ironic def set_option(self, name, value): """Set an option for a node.""" encoded = json.dumps(value) self.options[name] = value with db.ensure_transaction() as session: db.model_query(db.Option, session=session).filter_by( uuid=self.uuid, name=name).delete() db.Option(uuid=self.uuid, name=name, value=encoded).save( session) def finished(self, event, error=None): """Record status for this node and process a terminal transition. Also deletes look up attributes from the cache. :param event: the event to process :param error: error message """ self.release_lock() self.finished_at = timeutils.utcnow() self.error = error with db.ensure_transaction() as session: self.fsm_event(event) self._commit(finished_at=self.finished_at, error=self.error) db.model_query(db.Attribute, session=session).filter_by( node_uuid=self.uuid).delete() db.model_query(db.Option, session=session).filter_by( uuid=self.uuid).delete() def add_attribute(self, name, value, session=None): """Store look up attribute for a node in the database. :param name: attribute name :param value: attribute value or list of possible values :param session: optional existing database session """ if not isinstance(value, list): value = [value] with db.ensure_transaction(session) as session: for v in value: db.Attribute(uuid=uuidutils.generate_uuid(), name=name, value=v, node_uuid=self.uuid).save(session) # Invalidate attributes so they're loaded on next usage self._attributes = None @classmethod def from_row(cls, row, ironic=None, lock=None, node=None): """Construct NodeInfo from a database row.""" fields = {key: row[key] for key in ('uuid', 'version_id', 'state', 'started_at', 'finished_at', 'error')} return cls(ironic=ironic, lock=lock, node=node, **fields) def invalidate_cache(self): """Clear all cached info, so that it's reloaded next time.""" self._options = None self._node = None self._ports = None self._attributes = None self._ironic = None self._fsm = None self._state = None self._version_id = None def node(self, ironic=None): """Get Ironic node object associated with the cached node record.""" if self._node is None: ironic = ironic or self.ironic self._node = ir_utils.get_node(self.uuid, ironic=ironic) return self._node def create_ports(self, ports, ironic=None): """Create one or several ports for this node. :param ports: List of ports with all their attributes e.g [{'mac': xx, 'ip': xx, 'client_id': None}, {'mac': xx, 'ip': None, 'client_id': None}] It also support the old style of list of macs. A warning is issued if port already exists on a node. :param ironic: Ironic client to use instead of self.ironic """ existing_macs = [] for port in ports: mac = port extra = {} pxe_enabled = True if isinstance(port, dict): mac = port['mac'] client_id = port.get('client_id') if client_id: extra = {'client-id': client_id} pxe_enabled = port.get('pxe', True) if mac not in self.ports(): self._create_port(mac, ironic=ironic, extra=extra, pxe_enabled=pxe_enabled) else: existing_macs.append(mac) if existing_macs: LOG.warning('Did not create ports %s as they already exist', existing_macs, node_info=self) def ports(self, ironic=None): """Get Ironic port objects associated with the cached node record. This value is cached as well, use invalidate_cache() to clean. :return: dict MAC -> port object """ if self._ports is None: ironic = ironic or self.ironic port_list = ironic.node.list_ports(self.uuid, limit=0, detail=True) self._ports = {p.address: p for p in port_list} return self._ports def _create_port(self, mac, ironic=None, **kwargs): ironic = ironic or self.ironic try: port = ironic.port.create( node_uuid=self.uuid, address=mac, **kwargs) LOG.info('Port %(uuid)s was created successfully, MAC: %(mac)s,' 'attributes: %(attrs)s', {'uuid': port.uuid, 'mac': port.address, 'attrs': kwargs}, node_info=self) except exceptions.Conflict: LOG.warning('Port %s already exists, skipping', mac, node_info=self) # NOTE(dtantsur): we didn't get port object back, so we have to # reload ports on next access self._ports = None else: self._ports[mac] = port def patch(self, patches, ironic=None): """Apply JSON patches to a node. Refreshes cached node instance. :param patches: JSON patches to apply :param ironic: Ironic client to use instead of self.ironic :raises: ironicclient exceptions """ ironic = ironic or self.ironic # NOTE(aarefiev): support path w/o ahead forward slash # as Ironic cli does for patch in patches: if patch.get('path') and not patch['path'].startswith('/'): patch['path'] = '/' + patch['path'] LOG.debug('Updating node with patches %s', patches, node_info=self) self._node = ironic.node.update(self.uuid, patches) def patch_port(self, port, patches, ironic=None): """Apply JSON patches to a port. :param port: port object or its MAC :param patches: JSON patches to apply :param ironic: Ironic client to use instead of self.ironic """ ironic = ironic or self.ironic ports = self.ports() if isinstance(port, six.string_types): port = ports[port] LOG.debug('Updating port %(mac)s with patches %(patches)s', {'mac': port.address, 'patches': patches}, node_info=self) new_port = ironic.port.update(port.uuid, patches) ports[port.address] = new_port def update_properties(self, ironic=None, **props): """Update properties on a node. :param props: properties to update :param ironic: Ironic client to use instead of self.ironic """ ironic = ironic or self.ironic patches = [{'op': 'add', 'path': '/properties/%s' % k, 'value': v} for k, v in props.items()] self.patch(patches, ironic) def update_capabilities(self, ironic=None, **caps): """Update capabilities on a node. :param caps: capabilities to update :param ironic: Ironic client to use instead of self.ironic """ existing = ir_utils.capabilities_to_dict( self.node().properties.get('capabilities')) existing.update(caps) self.update_properties( ironic=ironic, capabilities=ir_utils.dict_to_capabilities(existing)) def delete_port(self, port, ironic=None): """Delete port. :param port: port object or its MAC :param ironic: Ironic client to use instead of self.ironic """ ironic = ironic or self.ironic ports = self.ports() if isinstance(port, six.string_types): port = ports[port] ironic.port.delete(port.uuid) del ports[port.address] def get_by_path(self, path): """Get field value by ironic-style path (e.g. /extra/foo). :param path: path to a field :returns: field value :raises: KeyError if field was not found """ path = path.strip('/') try: if '/' in path: prop, key = path.split('/', 1) return getattr(self.node(), prop)[key] else: return getattr(self.node(), path) except AttributeError: raise KeyError(path) def replace_field(self, path, func, **kwargs): """Replace a field on ironic node. :param path: path to a field as used by the ironic client :param func: function accepting an old value and returning a new one :param kwargs: if 'default' value is passed here, it will be used when no existing value is found. :raises: KeyError if value is not found and default is not set :raises: everything that patch() may raise """ ironic = kwargs.pop("ironic", None) or self.ironic try: value = self.get_by_path(path) op = 'replace' except KeyError: if 'default' in kwargs: value = kwargs['default'] op = 'add' else: raise ref_value = copy.deepcopy(value) value = func(value) if value != ref_value: self.patch([{'op': op, 'path': path, 'value': value}], ironic) def triggers_fsm_error_transition(errors=(Exception,), no_errors=(utils.NodeStateInvalidEvent, utils.NodeStateRaceCondition)): """Trigger an fsm error transition upon certain errors. It is assumed the first function arg of the decorated function is always a NodeInfo instance. :param errors: a tuple of exceptions upon which an error event is triggered. Re-raised. :param no_errors: a tuple of exceptions that won't trigger the error event. """ def outer(func): @six.wraps(func) def inner(node_info, *args, **kwargs): ret = None try: ret = func(node_info, *args, **kwargs) except no_errors as exc: LOG.debug('Not processing error event for the ' 'exception: %(exc)s raised by %(func)s', {'exc': exc, 'func': reflection.get_callable_name(func)}, node_info=node_info) except errors as exc: with excutils.save_and_reraise_exception(): LOG.error('Processing the error event because of an ' 'exception %(exc_type)s: %(exc)s raised by ' '%(func)s', {'exc_type': type(exc), 'exc': exc, 'func': reflection.get_callable_name(func)}, node_info=node_info) # an error event should be possible from all states node_info.finished(istate.Events.error, error=str(exc)) return ret return inner return outer def fsm_event_before(event, strict=False): """Trigger an fsm event before the function execution. It is assumed the first function arg of the decorated function is always a NodeInfo instance. :param event: the event to process before the function call :param strict: make an invalid fsm event trigger an error event """ def outer(func): @six.wraps(func) def inner(node_info, *args, **kwargs): LOG.debug('Processing event %(event)s before calling ' '%(func)s', {'event': event, 'func': func}, node_info=node_info) node_info.fsm_event(event, strict=strict) return func(node_info, *args, **kwargs) return inner return outer def fsm_event_after(event, strict=False): """Trigger an fsm event after the function execution. It is assumed the first function arg of the decorated function is always a NodeInfo instance. :param event: the event to process after the function call :param strict: make an invalid fsm event trigger an error event """ def outer(func): @six.wraps(func) def inner(node_info, *args, **kwargs): ret = func(node_info, *args, **kwargs) LOG.debug('Processing event %(event)s after calling ' '%(func)s', {'event': event, 'func': func}, node_info=node_info) node_info.fsm_event(event, strict=strict) return ret return inner return outer def fsm_transition(event, reentrant=True, **exc_kwargs): """Decorate a function to perform a (non-)reentrant transition. If True, reentrant transition will be performed at the end of a function call. If False, the transition will be performed before the function call. The function is decorated with the triggers_fsm_error_transition decorator as well. :param event: the event to bind the transition to. :param reentrant: whether the transition is reentrant. :param exc_kwargs: passed on to the triggers_fsm_error_transition decorator """ def outer(func): inner = triggers_fsm_error_transition(**exc_kwargs)(func) if not reentrant: return fsm_event_before(event, strict=True)(inner) return fsm_event_after(event)(inner) return outer def release_lock(func): """Decorate a node_info-function to release the node_info lock. Assumes the first parameter of the function func is always a NodeInfo instance. """ @six.wraps(func) def inner(node_info, *args, **kwargs): try: return func(node_info, *args, **kwargs) finally: # FIXME(milan) hacking the test cases to work # with release_lock.assert_called_once... if node_info._locked: node_info.release_lock() return inner def start_introspection(uuid, **kwargs): """Start the introspection of a node. If a node_info record exists in the DB, a start transition is used rather than dropping the record in order to check for the start transition validity in particular node state. :param uuid: Ironic node UUID :param kwargs: passed on to add_node() :raises: NodeStateInvalidEvent in case the start transition is invalid in the current node state :raises: NodeStateRaceCondition if a mismatch was detected between the node_info cache and the DB :returns: NodeInfo """ with db.ensure_transaction(): node_info = NodeInfo(uuid) # check that the start transition is possible try: node_info.fsm_event(istate.Events.start) except utils.NotFoundInCacheError: # node not found while in the fsm_event handler LOG.debug('Node missing in the cache; adding it now', node_info=node_info) state = istate.States.starting else: state = node_info.state return add_node(uuid, state, **kwargs) def add_node(uuid, state, **attributes): """Store information about a node under introspection. All existing information about this node is dropped. Empty values are skipped. :param uuid: Ironic node UUID :param state: The initial state of the node :param attributes: attributes known about this node (like macs, BMC etc); also ironic client instance may be passed under 'ironic' :returns: NodeInfo """ started_at = timeutils.utcnow() with db.ensure_transaction() as session: _delete_node(uuid) version_id = uuidutils.generate_uuid() db.Node(uuid=uuid, state=state, version_id=version_id, started_at=started_at).save(session) node_info = NodeInfo(uuid=uuid, state=state, started_at=started_at, version_id=version_id, ironic=attributes.pop('ironic', None)) for (name, value) in attributes.items(): if not value: continue node_info.add_attribute(name, value, session=session) return node_info def delete_nodes_not_in_list(uuids): """Delete nodes which don't exist in Ironic node UUIDs. :param uuids: Ironic node UUIDs """ inspector_uuids = _list_node_uuids() for uuid in inspector_uuids - uuids: LOG.warning('Node %s was deleted from Ironic, dropping from Ironic ' 'Inspector database', uuid) with _get_lock_ctx(uuid): _delete_node(uuid) def _delete_node(uuid, session=None): """Delete information about a node. :param uuid: Ironic node UUID :param session: optional existing database session """ with db.ensure_transaction(session) as session: db.model_query(db.Attribute, session=session).filter_by( node_uuid=uuid).delete() for model in (db.Option, db.Node): db.model_query(model, session=session).filter_by(uuid=uuid).delete() def introspection_active(): """Check if introspection is active for at least one node.""" # FIXME(dtantsur): is there a better way to express it? return (db.model_query(db.Node.uuid).filter_by(finished_at=None).first() is not None) def active_macs(): """List all MAC's that are on introspection right now.""" return ({x.value for x in db.model_query(db.Attribute.value). filter_by(name=MACS_ATTRIBUTE)}) def _list_node_uuids(): """Get all nodes' uuid from cache. :returns: Set of nodes' uuid. """ return {x.uuid for x in db.model_query(db.Node.uuid)} def get_node(node_id, ironic=None, locked=False): """Get node from cache. :param node_id: node UUID or name. :param ironic: optional ironic client instance :param locked: if True, get a lock on node before fetching its data :returns: structure NodeInfo. """ if uuidutils.is_uuid_like(node_id): node = None uuid = node_id else: node = ir_utils.get_node(node_id, ironic=ironic) uuid = node.uuid if locked: lock = _get_lock(uuid) lock.acquire() else: lock = None try: row = db.model_query(db.Node).filter_by(uuid=uuid).first() if row is None: raise utils.Error(_('Could not find node %s in cache') % uuid, code=404) return NodeInfo.from_row(row, ironic=ironic, lock=lock, node=node) except Exception: with excutils.save_and_reraise_exception(): if lock is not None: lock.release() def find_node(**attributes): """Find node in cache. Looks up a node based on attributes in a best-match fashion. This function acquires a lock on a node. :param attributes: attributes known about this node (like macs, BMC etc) also ironic client instance may be passed under 'ironic' :returns: structure NodeInfo with attributes ``uuid`` and ``created_at`` :raises: Error if node is not found or multiple nodes match the attributes """ ironic = attributes.pop('ironic', None) # NOTE(dtantsur): sorting is not required, but gives us predictability found = collections.Counter() for (name, value) in sorted(attributes.items()): if not value: LOG.debug('Empty value for attribute %s', name) continue if not isinstance(value, list): value = [value] LOG.debug('Trying to use %s of value %s for node look up', name, value) value_list = [] for v in value: value_list.append("name='%s' AND value='%s'" % (name, v)) stmt = ('select distinct node_uuid from attributes where ' + ' OR '.join(value_list)) rows = (db.model_query(db.Attribute.node_uuid).from_statement( text(stmt)).all()) found.update(row.node_uuid for row in rows) if not found: raise utils.NotFoundInCacheError(_( 'Could not find a node for attributes %s') % attributes) most_common = found.most_common() LOG.debug('The following nodes match the attributes: %(attributes)s, ' 'scoring: %(most_common)s', {'most_common': ', '.join('%s: %d' % tpl for tpl in most_common), 'attributes': ', '.join('%s=%s' % tpl for tpl in attributes.items())}) # NOTE(milan) most_common is sorted, higher scores first highest_score = most_common[0][1] found = [item[0] for item in most_common if highest_score == item[1]] if len(found) > 1: raise utils.Error(_( 'Multiple nodes match the same number of attributes ' '%(attr)s: %(found)s') % {'attr': attributes, 'found': found}, code=404) uuid = found.pop() node_info = NodeInfo(uuid=uuid, ironic=ironic) node_info.acquire_lock() try: row = (db.model_query(db.Node.started_at, db.Node.finished_at). filter_by(uuid=uuid).first()) if not row: raise utils.Error(_( 'Could not find node %s in introspection cache, ' 'probably it\'s not on introspection now') % uuid, code=404) if row.finished_at: raise utils.Error(_( 'Introspection for node %(node)s already finished on ' '%(finish)s') % {'node': uuid, 'finish': row.finished_at}) node_info.started_at = row.started_at return node_info except Exception: with excutils.save_and_reraise_exception(): node_info.release_lock() def clean_up(): """Clean up the cache. * Finish introspection for timed out nodes. * Drop outdated node status information. :return: list of timed out node UUID's """ if CONF.node_status_keep_time > 0: status_keep_threshold = (timeutils.utcnow() - datetime.timedelta( seconds=CONF.node_status_keep_time)) with db.ensure_transaction() as session: db.model_query(db.Node, session=session).filter( db.Node.finished_at.isnot(None), db.Node.finished_at < status_keep_threshold).delete() timeout = CONF.timeout if timeout <= 0: return [] threshold = timeutils.utcnow() - datetime.timedelta(seconds=timeout) uuids = [row.uuid for row in db.model_query(db.Node.uuid).filter( db.Node.started_at < threshold, db.Node.finished_at.is_(None)).all()] if not uuids: return [] LOG.error('Introspection for nodes %s has timed out', uuids) for u in uuids: node_info = get_node(u, locked=True) try: if node_info.finished_at or node_info.started_at > threshold: continue if node_info.state != istate.States.waiting: LOG.error('Something went wrong, timeout occurred ' 'while introspection in "%s" state', node_info.state, node_info=node_info) node_info.finished( istate.Events.timeout, error='Introspection timeout') finally: node_info.release_lock() return uuids def create_node(driver, ironic=None, **attributes): """Create ironic node and cache it. * Create new node in ironic. * Cache it in inspector. * Sets node_info state to enrolling. :param driver: driver for Ironic node. :param ironic: ronic client instance. :param attributes: dict, additional keyword arguments to pass to the ironic client on node creation. :return: NodeInfo, or None in case error happened. """ if ironic is None: ironic = ir_utils.get_client() try: node = ironic.node.create(driver=driver, **attributes) except exceptions.InvalidAttribute as e: LOG.error('Failed to create new node: %s', e) else: LOG.info('Node %s was created successfully', node.uuid) return add_node(node.uuid, istate.States.enrolling, ironic=ironic) def get_node_list(ironic=None, marker=None, limit=None): """Get node list from the cache. The list of the nodes is ordered based on the (started_at, uuid) attribute pair, newer items first. :param ironic: optional ironic client instance :param marker: pagination marker (an UUID or None) :param limit: pagination limit; None for default CONF.api_max_limit :returns: a list of NodeInfo instances. """ if marker is not None: # uuid marker -> row marker for pagination marker = db.model_query(db.Node).get(marker) if marker is None: raise utils.Error(_('Node not found for marker: %s') % marker, code=404) rows = db.model_query(db.Node) # ordered based on (started_at, uuid); newer first rows = db_utils.paginate_query(rows, db.Node, limit, ('started_at', 'uuid'), marker=marker, sort_dir='desc') return [NodeInfo.from_row(row, ironic=ironic) for row in rows]