import collections import copy import logging import threading import time from concurrent.futures import Future from typing import Optional from aiokafka import errors as Errors from aiokafka.conn import collect_hosts from aiokafka.structs import BrokerMetadata, PartitionMetadata, TopicPartition log = logging.getLogger(__name__) class ClusterMetadata: """ A class to manage kafka cluster metadata. This class does not perform any IO. It simply updates internal state given API responses (MetadataResponse, GroupCoordinatorResponse). Keyword Arguments: retry_backoff_ms (int): Milliseconds to backoff when retrying on errors. Default: 100. metadata_max_age_ms (int): The period of time in milliseconds after which we force a refresh of metadata even if we haven't seen any partition leadership changes to proactively discover any new brokers or partitions. Default: 300000 bootstrap_servers: 'host[:port]' string (or list of 'host[:port]' strings) that the client should contact to bootstrap initial cluster metadata. This does not have to be the full node list. It just needs to have at least one broker that will respond to a Metadata API Request. Default port is 9092. If no servers are specified, will default to localhost:9092. """ DEFAULT_CONFIG = { "retry_backoff_ms": 100, "metadata_max_age_ms": 300000, "bootstrap_servers": [], } def __init__(self, **configs): self._brokers = {} # node_id -> BrokerMetadata self._partitions = {} # topic -> partition -> PartitionMetadata # node_id -> {TopicPartition...} self._broker_partitions = collections.defaultdict(set) self._groups = {} # group_name -> node_id self._last_refresh_ms = 0 self._last_successful_refresh_ms = 0 self._need_update = True self._future = None self._listeners = set() self._lock = threading.Lock() self.need_all_topic_metadata = False self.unauthorized_topics = set() self.internal_topics = set() self.controller = None self.config = copy.copy(self.DEFAULT_CONFIG) for key in self.config: if key in configs: self.config[key] = configs[key] self._bootstrap_brokers = self._generate_bootstrap_brokers() self._coordinator_brokers = {} self._coordinators = {} self._coordinator_by_key = {} def _generate_bootstrap_brokers(self): # collect_hosts does not perform DNS, so we should be fine to re-use bootstrap_hosts = collect_hosts(self.config["bootstrap_servers"]) brokers = {} for i, (host, port, _) in enumerate(bootstrap_hosts): node_id = f"bootstrap-{i}" brokers[node_id] = BrokerMetadata(node_id, host, port, None) return brokers def is_bootstrap(self, node_id): return node_id in self._bootstrap_brokers def brokers(self): """Get all BrokerMetadata Returns: set: {BrokerMetadata, ...} """ return set(self._brokers.values()) or set(self._bootstrap_brokers.values()) def broker_metadata(self, broker_id): """Get BrokerMetadata Arguments: broker_id (int): node_id for a broker to check Returns: BrokerMetadata or None if not found """ return ( self._brokers.get(broker_id) or self._bootstrap_brokers.get(broker_id) or self._coordinator_brokers.get(broker_id) ) def partitions_for_topic(self, topic: str) -> Optional[set[int]]: """Return set of all partitions for topic (whether available or not) Arguments: topic (str): topic to check for partitions Returns: set: {partition (int), ...} """ if topic not in self._partitions: return None return set(self._partitions[topic].keys()) def available_partitions_for_topic(self, topic): """Return set of partitions with known leaders Arguments: topic (str): topic to check for partitions Returns: set: {partition (int), ...} None if topic not found. """ if topic not in self._partitions: return None return { partition for partition, metadata in self._partitions[topic].items() if metadata.leader != -1 } def leader_for_partition(self, partition): """Return node_id of leader, -1 unavailable, None if unknown.""" if partition.topic not in self._partitions: return None partitions = self._partitions[partition.topic] if partition.partition not in partitions: return None return partitions[partition.partition].leader def partitions_for_broker(self, broker_id): """Return TopicPartitions for which the broker is a leader. Arguments: broker_id (int): node id for a broker Returns: set: {TopicPartition, ...} None if the broker either has no partitions or does not exist. """ return self._broker_partitions.get(broker_id) def coordinator_for_group(self, group): """Return node_id of group coordinator. Arguments: group (str): name of consumer group Returns: int: node_id for group coordinator None if the group does not exist. """ return self._groups.get(group) def request_update(self): """Flags metadata for update, return Future() Actual update must be handled separately. This method will only change the reported ttl() Returns: Future (value will be the cluster object after update) """ with self._lock: self._need_update = True if not self._future or self._future.is_done: self._future = Future() return self._future def topics(self, exclude_internal_topics=True): """Get set of known topics. Arguments: exclude_internal_topics (bool): Whether records from internal topics (such as offsets) should be exposed to the consumer. If set to True the only way to receive records from an internal topic is subscribing to it. Default True Returns: set: {topic (str), ...} """ topics = set(self._partitions.keys()) if exclude_internal_topics: return topics - self.internal_topics else: return topics def failed_update(self, exception): """Update cluster state given a failed MetadataRequest.""" f = None with self._lock: if self._future: f = self._future self._future = None if f: f.set_exception(exception) self._last_refresh_ms = time.time() * 1000 def update_metadata(self, metadata): """Update cluster state given a MetadataResponse. Arguments: metadata (MetadataResponse): broker response to a metadata request Returns: None """ if not metadata.brokers: log.warning("No broker metadata found in MetadataResponse -- ignoring.") self.failed_update(Errors.MetadataEmptyBrokerList(metadata)) return _new_brokers = {} for broker in metadata.brokers: if metadata.API_VERSION == 0: node_id, host, port = broker rack = None else: node_id, host, port, rack = broker _new_brokers.update({node_id: BrokerMetadata(node_id, host, port, rack)}) if metadata.API_VERSION == 0: _new_controller = None else: _new_controller = _new_brokers.get(metadata.controller_id) _new_partitions = {} _new_broker_partitions = collections.defaultdict(set) _new_unauthorized_topics = set() _new_internal_topics = set() for topic_data in metadata.topics: if metadata.API_VERSION == 0: error_code, topic, partitions = topic_data is_internal = False else: error_code, topic, is_internal, partitions = topic_data if is_internal: _new_internal_topics.add(topic) error_type = Errors.for_code(error_code) if error_type is Errors.NoError: _new_partitions[topic] = {} # Starting with v5, MetadataResponse contains more than 5 fields for p_error, partition, leader, replicas, isr, *_ in partitions: _new_partitions[topic][partition] = PartitionMetadata( topic=topic, partition=partition, leader=leader, replicas=replicas, isr=isr, error=p_error, ) if leader != -1: _new_broker_partitions[leader].add( TopicPartition(topic, partition) ) # Specific topic errors can be ignored if this is a full metadata fetch elif self.need_all_topic_metadata: continue elif error_type is Errors.LeaderNotAvailableError: log.warning( "Topic %s is not available during auto-create initialization", topic, ) elif error_type is Errors.UnknownTopicOrPartitionError: log.error("Topic %s not found in cluster metadata", topic) elif error_type is Errors.TopicAuthorizationFailedError: log.error("Topic %s is not authorized for this client", topic) _new_unauthorized_topics.add(topic) elif error_type is Errors.InvalidTopicError: log.error("'%s' is not a valid topic name", topic) else: log.error("Error fetching metadata for topic %s: %s", topic, error_type) with self._lock: self._brokers = _new_brokers self.controller = _new_controller self._partitions = _new_partitions self._broker_partitions = _new_broker_partitions self.unauthorized_topics = _new_unauthorized_topics self.internal_topics = _new_internal_topics f = None if self._future: f = self._future self._future = None self._need_update = False now = time.time() * 1000 self._last_refresh_ms = now self._last_successful_refresh_ms = now if f: f.set_result(self) log.debug("Updated cluster metadata to %s", self) for listener in self._listeners: listener(self) if self.need_all_topic_metadata: # the listener may change the interested topics, # which could cause another metadata refresh. # If we have already fetched all topics, however, # another fetch should be unnecessary. self._need_update = False def add_listener(self, listener): """Add a callback function to be called on each metadata update""" self._listeners.add(listener) def remove_listener(self, listener): """Remove a previously added listener callback""" self._listeners.remove(listener) def add_group_coordinator(self, group, response): """Update with metadata for a group coordinator Arguments: group (str): name of group from GroupCoordinatorRequest response (GroupCoordinatorResponse): broker response Returns: string: coordinator node_id if metadata is updated, None on error """ log.debug("Updating coordinator for %s: %s", group, response) error_type = Errors.for_code(response.error_code) if error_type is not Errors.NoError: log.error("GroupCoordinatorResponse error: %s", error_type) self._groups[group] = -1 return None # Use a coordinator-specific node id so that group requests # get a dedicated connection node_id = f"coordinator-{response.coordinator_id}" coordinator = BrokerMetadata(node_id, response.host, response.port, None) log.info("Group coordinator for %s is %s", group, coordinator) self._coordinator_brokers[node_id] = coordinator self._groups[group] = node_id return node_id def with_partitions(self, partitions_to_add): """Returns a copy of cluster metadata with partitions added""" new_metadata = ClusterMetadata(**self.config) new_metadata._brokers = copy.deepcopy(self._brokers) new_metadata._partitions = copy.deepcopy(self._partitions) new_metadata._broker_partitions = copy.deepcopy(self._broker_partitions) new_metadata._groups = copy.deepcopy(self._groups) new_metadata.internal_topics = copy.deepcopy(self.internal_topics) new_metadata.unauthorized_topics = copy.deepcopy(self.unauthorized_topics) for partition in partitions_to_add: new_metadata._partitions[partition.topic][partition.partition] = partition if partition.leader is not None and partition.leader != -1: new_metadata._broker_partitions[partition.leader].add( TopicPartition(partition.topic, partition.partition) ) return new_metadata def coordinator_metadata(self, node_id): return self._coordinators.get(node_id) def add_coordinator(self, node_id, host, port, rack=None, *, purpose): """Keep track of all coordinator nodes separately and remove them if a new one was elected for the same purpose (For example group coordinator for group X). """ if purpose in self._coordinator_by_key: old_id = self._coordinator_by_key.pop(purpose) del self._coordinators[old_id] self._coordinators[node_id] = BrokerMetadata(node_id, host, port, rack) self._coordinator_by_key[purpose] = node_id def __str__(self): return "ClusterMetadata(brokers: %d, topics: %d, groups: %d)" % ( len(self._brokers), len(self._partitions), len(self._groups), )