Source code for apache_beam.io.gcp.pubsub

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"""Google Cloud PubSub sources and sinks.

Cloud Pub/Sub sources and sinks are currently supported only in streaming
pipelines, during remote execution.

This API is currently under development and is subject to change.

**Updates to the I/O connector code**

For any significant updates to this I/O connector, please consider involving
corresponding code reviewers mentioned in
https://github.com/apache/beam/blob/master/sdks/python/OWNERS
"""

# pytype: skip-file

import re
from typing import Any
from typing import List
from typing import NamedTuple
from typing import Optional
from typing import Tuple

from apache_beam import coders
from apache_beam.io import iobase
from apache_beam.io.iobase import Read
from apache_beam.io.iobase import Write
from apache_beam.transforms import Flatten
from apache_beam.transforms import Map
from apache_beam.transforms import PTransform
from apache_beam.transforms.display import DisplayDataItem
from apache_beam.utils.annotations import deprecated

try:
  from google.cloud import pubsub
except ImportError:
  pubsub = None

__all__ = [
    'MultipleReadFromPubSub',
    'PubsubMessage',
    'PubSubSourceDescriptor',
    'ReadFromPubSub',
    'ReadStringsFromPubSub',
    'WriteStringsToPubSub',
    'WriteToPubSub'
]


[docs]class PubsubMessage(object): """Represents a Cloud Pub/Sub message. Message payload includes the data and attributes fields. For the payload to be valid, at least one of its fields must be non-empty. Attributes: data: (bytes) Message data. May be None. attributes: (dict) Key-value map of str to str, containing both user-defined and service generated attributes (such as id_label and timestamp_attribute). May be None. message_id: (str) ID of the message, assigned by the pubsub service when the message is published. Guaranteed to be unique within the topic. Will be reset to None if the message is being written to pubsub. publish_time: (datetime) Time at which the message was published. Will be reset to None if the Message is being written to pubsub. ordering_key: (str) If non-empty, identifies related messages for which publish order is respected by the PubSub subscription. """ def __init__( self, data, attributes, message_id=None, publish_time=None, ordering_key=""): if data is None and not attributes: raise ValueError( 'Either data (%r) or attributes (%r) must be set.', data, attributes) self.data = data self.attributes = attributes self.message_id = message_id self.publish_time = publish_time self.ordering_key = ordering_key def __hash__(self): return hash((self.data, frozenset(self.attributes.items()))) def __eq__(self, other): return isinstance(other, PubsubMessage) and ( self.data == other.data and self.attributes == other.attributes) def __repr__(self): return 'PubsubMessage(%s, %s)' % (self.data, self.attributes) @staticmethod def _from_proto_str(proto_msg): # type: (bytes) -> PubsubMessage """Construct from serialized form of ``PubsubMessage``. Args: proto_msg: String containing a serialized protobuf of type https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#google.pubsub.v1.PubsubMessage Returns: A new PubsubMessage object. """ msg = pubsub.types.PubsubMessage.deserialize(proto_msg) # Convert ScalarMapContainer to dict. attributes = dict((key, msg.attributes[key]) for key in msg.attributes) return PubsubMessage( msg.data, attributes, msg.message_id, msg.publish_time, msg.ordering_key) def _to_proto_str(self, for_publish=False): """Get serialized form of ``PubsubMessage``. The serialized message is validated against pubsub message limits specified at https://cloud.google.com/pubsub/quotas#resource_limits Args: proto_msg: str containing a serialized protobuf. for_publish: bool, if True strip out message fields which cannot be published (currently message_id and publish_time) per https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#pubsubmessage Returns: A str containing a serialized protobuf of type https://cloud.google.com/pubsub/docs/reference/rpc/google.pubsub.v1#google.pubsub.v1.PubsubMessage containing the payload of this object. """ msg = pubsub.types.PubsubMessage() if len(self.data) > (10 << 20): raise ValueError('A pubsub message data field must not exceed 10MB') msg.data = self.data if self.attributes: if len(self.attributes) > 100: raise ValueError( 'A pubsub message must not have more than 100 attributes.') for key, value in self.attributes.items(): if len(key) > 256: raise ValueError( 'A pubsub message attribute key must not exceed 256 bytes.') if len(value) > 1024: raise ValueError( 'A pubsub message attribute value must not exceed 1024 bytes') msg.attributes[key] = value if not for_publish: if self.message_id: msg.message_id = self.message_id if self.publish_time: msg.publish_time = self.publish_time if len(self.ordering_key) > 1024: raise ValueError( 'A pubsub message ordering key must not exceed 1024 bytes.') msg.ordering_key = self.ordering_key serialized = pubsub.types.PubsubMessage.serialize(msg) if len(serialized) > (10 << 20): raise ValueError( 'Serialized pubsub message exceeds the publish request limit of 10MB') return serialized @staticmethod def _from_message(msg): # type: (Any) -> PubsubMessage """Construct from ``google.cloud.pubsub_v1.subscriber.message.Message``. https://googleapis.github.io/google-cloud-python/latest/pubsub/subscriber/api/message.html """ # Convert ScalarMapContainer to dict. attributes = dict((key, msg.attributes[key]) for key in msg.attributes) pubsubmessage = PubsubMessage(msg.data, attributes) if msg.message_id: pubsubmessage.message_id = msg.message_id if msg.publish_time: pubsubmessage.publish_time = msg.publish_time if msg.ordering_key: pubsubmessage.ordering_key = msg.ordering_key return pubsubmessage
[docs]class ReadFromPubSub(PTransform): """A ``PTransform`` for reading from Cloud Pub/Sub.""" # Implementation note: This ``PTransform`` is overridden by Directrunner. def __init__( self, topic=None, # type: Optional[str] subscription=None, # type: Optional[str] id_label=None, # type: Optional[str] with_attributes=False, # type: bool timestamp_attribute=None # type: Optional[str] ): # type: (...) -> None """Initializes ``ReadFromPubSub``. Args: topic: Cloud Pub/Sub topic in the form "projects/<project>/topics/<topic>". If provided, subscription must be None. subscription: Existing Cloud Pub/Sub subscription to use in the form "projects/<project>/subscriptions/<subscription>". If not specified, a temporary subscription will be created from the specified topic. If provided, topic must be None. id_label: The attribute on incoming Pub/Sub messages to use as a unique record identifier. When specified, the value of this attribute (which can be any string that uniquely identifies the record) will be used for deduplication of messages. If not provided, we cannot guarantee that no duplicate data will be delivered on the Pub/Sub stream. In this case, deduplication of the stream will be strictly best effort. with_attributes: True - output elements will be :class:`~PubsubMessage` objects. False - output elements will be of type ``bytes`` (message data only). timestamp_attribute: Message value to use as element timestamp. If None, uses message publishing time as the timestamp. Timestamp values should be in one of two formats: - A numerical value representing the number of milliseconds since the Unix epoch. - A string in RFC 3339 format, UTC timezone. Example: ``2015-10-29T23:41:41.123Z``. The sub-second component of the timestamp is optional, and digits beyond the first three (i.e., time units smaller than milliseconds) may be ignored. """ super().__init__() self.with_attributes = with_attributes self._source = _PubSubSource( topic=topic, subscription=subscription, id_label=id_label, with_attributes=self.with_attributes, timestamp_attribute=timestamp_attribute)
[docs] def expand(self, pvalue): # TODO(BEAM-27443): Apply a proper transform rather than Read. pcoll = pvalue.pipeline | Read(self._source) pcoll.element_type = bytes if self.with_attributes: pcoll = pcoll | Map(PubsubMessage._from_proto_str) pcoll.element_type = PubsubMessage return pcoll
[docs] def to_runner_api_parameter(self, context): # Required as this is identified by type in PTransformOverrides. # TODO(https://github.com/apache/beam/issues/18713): Use an actual URN here. return self.to_runner_api_pickled(context)
[docs]@deprecated(since='2.7.0', extra_message='Use ReadFromPubSub instead.') def ReadStringsFromPubSub(topic=None, subscription=None, id_label=None): return _ReadStringsFromPubSub(topic, subscription, id_label)
class _ReadStringsFromPubSub(PTransform): """This class is deprecated. Use ``ReadFromPubSub`` instead.""" def __init__(self, topic=None, subscription=None, id_label=None): super().__init__() self.topic = topic self.subscription = subscription self.id_label = id_label def expand(self, pvalue): p = ( pvalue.pipeline | ReadFromPubSub( self.topic, self.subscription, self.id_label, with_attributes=False) | 'DecodeString' >> Map(lambda b: b.decode('utf-8'))) p.element_type = str return p
[docs]@deprecated(since='2.7.0', extra_message='Use WriteToPubSub instead.') def WriteStringsToPubSub(topic): return _WriteStringsToPubSub(topic)
class _WriteStringsToPubSub(PTransform): """This class is deprecated. Use ``WriteToPubSub`` instead.""" def __init__(self, topic): """Initializes ``_WriteStringsToPubSub``. Attributes: topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>". """ super().__init__() self.topic = topic def expand(self, pcoll): pcoll = pcoll | 'EncodeString' >> Map(lambda s: s.encode('utf-8')) pcoll.element_type = bytes return pcoll | WriteToPubSub(self.topic)
[docs]class WriteToPubSub(PTransform): """A ``PTransform`` for writing messages to Cloud Pub/Sub.""" # Implementation note: This ``PTransform`` is overridden by Directrunner. def __init__( self, topic, # type: str with_attributes=False, # type: bool id_label=None, # type: Optional[str] timestamp_attribute=None # type: Optional[str] ): # type: (...) -> None """Initializes ``WriteToPubSub``. Args: topic: Cloud Pub/Sub topic in the form "/topics/<project>/<topic>". with_attributes: True - input elements will be :class:`~PubsubMessage` objects. False - input elements will be of type ``bytes`` (message data only). id_label: If set, will set an attribute for each Cloud Pub/Sub message with the given name and a unique value. This attribute can then be used in a ReadFromPubSub PTransform to deduplicate messages. timestamp_attribute: If set, will set an attribute for each Cloud Pub/Sub message with the given name and the message's publish time as the value. """ super().__init__() self.with_attributes = with_attributes self.id_label = id_label self.timestamp_attribute = timestamp_attribute self.project, self.topic_name = parse_topic(topic) self.full_topic = topic self._sink = _PubSubSink(topic, id_label, timestamp_attribute)
[docs] @staticmethod def message_to_proto_str(element): # type: (PubsubMessage) -> bytes if not isinstance(element, PubsubMessage): raise TypeError( 'Unexpected element. Type: %s (expected: PubsubMessage), ' 'value: %r' % (type(element), element)) return element._to_proto_str(for_publish=True)
[docs] @staticmethod def bytes_to_proto_str(element): # type: (bytes) -> bytes msg = PubsubMessage(element, {}) return msg._to_proto_str(for_publish=True)
[docs] def expand(self, pcoll): if self.with_attributes: pcoll = pcoll | 'ToProtobuf' >> Map(self.message_to_proto_str) else: pcoll = pcoll | 'ToProtobuf' >> Map(self.bytes_to_proto_str) pcoll.element_type = bytes return pcoll | Write(self._sink)
[docs] def to_runner_api_parameter(self, context): # Required as this is identified by type in PTransformOverrides. # TODO(https://github.com/apache/beam/issues/18713): Use an actual URN here. return self.to_runner_api_pickled(context)
[docs] def display_data(self): return { 'topic': DisplayDataItem(self.full_topic, label='Pubsub Topic'), 'id_label': DisplayDataItem(self.id_label, label='ID Label Attribute'), 'with_attributes': DisplayDataItem( True, label='With Attributes').drop_if_none(), 'timestamp_attribute': DisplayDataItem( self.timestamp_attribute, label='Timestamp Attribute'), }
PROJECT_ID_REGEXP = '[a-z][-a-z0-9:.]{4,61}[a-z0-9]' SUBSCRIPTION_REGEXP = 'projects/([^/]+)/subscriptions/(.+)' TOPIC_REGEXP = 'projects/([^/]+)/topics/(.+)' def parse_topic(full_topic: str) -> Tuple[str, str]: match = re.match(TOPIC_REGEXP, full_topic) if not match: raise ValueError( 'PubSub topic must be in the form "projects/<project>/topics' '/<topic>" (got %r).' % full_topic) project, topic_name = match.group(1), match.group(2) if not re.match(PROJECT_ID_REGEXP, project): raise ValueError('Invalid PubSub project name: %r.' % project) return project, topic_name def parse_subscription(full_subscription): match = re.match(SUBSCRIPTION_REGEXP, full_subscription) if not match: raise ValueError( 'PubSub subscription must be in the form "projects/<project>' '/subscriptions/<subscription>" (got %r).' % full_subscription) project, subscription_name = match.group(1), match.group(2) if not re.match(PROJECT_ID_REGEXP, project): raise ValueError('Invalid PubSub project name: %r.' % project) return project, subscription_name # TODO(BEAM-27443): Remove (or repurpose as a proper PTransform). class _PubSubSource(iobase.SourceBase): """Source for a Cloud Pub/Sub topic or subscription. This ``NativeSource`` is overridden by a native Pubsub implementation. Attributes: with_attributes: If False, will fetch just message data. Otherwise, fetches ``PubsubMessage`` protobufs. """ def __init__( self, topic=None, # type: Optional[str] subscription=None, # type: Optional[str] id_label=None, # type: Optional[str] with_attributes=False, # type: bool timestamp_attribute=None # type: Optional[str] ): self.coder = coders.BytesCoder() self.full_topic = topic self.full_subscription = subscription self.topic_name = None self.subscription_name = None self.id_label = id_label self.with_attributes = with_attributes self.timestamp_attribute = timestamp_attribute # Perform some validation on the topic and subscription. if not (topic or subscription): raise ValueError('Either a topic or subscription must be provided.') if topic and subscription: raise ValueError('Only one of topic or subscription should be provided.') if topic: self.project, self.topic_name = parse_topic(topic) if subscription: self.project, self.subscription_name = parse_subscription(subscription) def display_data(self): return { 'id_label': DisplayDataItem(self.id_label, label='ID Label Attribute').drop_if_none(), 'topic': DisplayDataItem(self.full_topic, label='Pubsub Topic').drop_if_none(), 'subscription': DisplayDataItem( self.full_subscription, label='Pubsub Subscription').drop_if_none(), 'with_attributes': DisplayDataItem( self.with_attributes, label='With Attributes').drop_if_none(), 'timestamp_attribute': DisplayDataItem( self.timestamp_attribute, label='Timestamp Attribute').drop_if_none(), } def default_output_coder(self): return self.coder def is_bounded(self): return False # TODO(BEAM-27443): Remove in favor of a proper WriteToPubSub transform. class _PubSubSink(object): """Sink for a Cloud Pub/Sub topic. This ``NativeSource`` is overridden by a native Pubsub implementation. """ def __init__( self, topic: str, id_label: Optional[str], timestamp_attribute: Optional[str], ): self.coder = coders.BytesCoder() self.full_topic = topic self.id_label = id_label self.timestamp_attribute = timestamp_attribute self.project, self.topic_name = parse_topic(topic)
[docs]class PubSubSourceDescriptor(NamedTuple): """A PubSub source descriptor for ``MultipleReadFromPubSub``` Attributes: source: Existing Cloud Pub/Sub topic or subscription to use in the form "projects/<project>/topics/<topic>" or "projects/<project>/subscriptions/<subscription>" id_label: The attribute on incoming Pub/Sub messages to use as a unique record identifier. When specified, the value of this attribute (which can be any string that uniquely identifies the record) will be used for deduplication of messages. If not provided, we cannot guarantee that no duplicate data will be delivered on the Pub/Sub stream. In this case, deduplication of the stream will be strictly best effort. timestamp_attribute: Message value to use as element timestamp. If None, uses message publishing time as the timestamp. Timestamp values should be in one of two formats: - A numerical value representing the number of milliseconds since the Unix epoch. - A string in RFC 3339 format, UTC timezone. Example: ``2015-10-29T23:41:41.123Z``. The sub-second component of the timestamp is optional, and digits beyond the first three (i.e., time units smaller than milliseconds) may be ignored. """ source: str id_label: str = None timestamp_attribute: str = None
PUBSUB_DESCRIPTOR_REGEXP = 'projects/([^/]+)/(topics|subscriptions)/(.+)'
[docs]class MultipleReadFromPubSub(PTransform): """A ``PTransform`` that expands ``ReadFromPubSub`` to read from multiple ``PubSubSourceDescriptor``. The `MultipleReadFromPubSub` transform allows you to read multiple topics and/or subscriptions using just one transform. It is the recommended transform to read multiple Pub/Sub sources when the output `PCollection` are going to be flattened. The transform takes a list of `PubSubSourceDescriptor` and organize them by type (topic / subscription) and project::: topic_1 = PubSubSourceDescriptor('projects/myproject/topics/a_topic') topic_2 = PubSubSourceDescriptor( 'projects/myproject2/topics/b_topic', 'my_label', 'my_timestamp_attribute') subscription_1 = PubSubSourceDescriptor( 'projects/myproject/subscriptions/a_subscription') results = pipeline | MultipleReadFromPubSub( [topic_1, topic_2, subscription_1]) """ def __init__( self, pubsub_source_descriptors, # type: List[PubSubSourceDescriptor] with_attributes=False, # type: bool ): """Initializes ``PubSubMultipleReader``. Args: pubsub_source_descriptors: List of Cloud Pub/Sub topics or subscriptions of type `~PubSubSourceDescriptor`. with_attributes: True - input elements will be :class:`~PubsubMessage` objects. False - input elements will be of type ``bytes`` (message data only). """ self.pubsub_source_descriptors = pubsub_source_descriptors self.with_attributes = with_attributes for descriptor in self.pubsub_source_descriptors: match_descriptor = re.match(PUBSUB_DESCRIPTOR_REGEXP, descriptor.source) if not match_descriptor: raise ValueError( 'PubSub source descriptor must be in the form "projects/<project>' '/topics/<topic>" or "projects/<project>/subscription' '/<subscription>" (got %r).' % descriptor.source)
[docs] def expand(self, pcol): sources_pcol = [] for descriptor in self.pubsub_source_descriptors: source_match = re.match(PUBSUB_DESCRIPTOR_REGEXP, descriptor.source) source_project = source_match.group(1) source_type = source_match.group(2) source_name = source_match.group(3) read_step_name = 'PubSub %s/project:%s/Read %s' % ( source_type, source_project, source_name) if source_type == 'topics': current_source = pcol | read_step_name >> ReadFromPubSub( topic=descriptor.source, id_label=descriptor.id_label, with_attributes=self.with_attributes, timestamp_attribute=descriptor.timestamp_attribute) else: current_source = pcol | read_step_name >> ReadFromPubSub( subscription=descriptor.source, id_label=descriptor.id_label, with_attributes=self.with_attributes, timestamp_attribute=descriptor.timestamp_attribute) sources_pcol.append(current_source) return tuple(sources_pcol) | Flatten()