#
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to You 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.
#
"""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.
"""
# 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.iobase import Read
from apache_beam.io.iobase import Write
from apache_beam.runners.dataflow.native_io import iobase as dataflow_io
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.
"""
def __init__(self, data, attributes):
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
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.pubsub_pb2.PubsubMessage()
msg.ParseFromString(proto_msg)
# Convert ScalarMapContainer to dict.
attributes = dict((key, msg.attributes[key]) for key in msg.attributes)
return PubsubMessage(msg.data, attributes)
def _to_proto_str(self):
"""Get serialized form of ``PubsubMessage``.
Args:
proto_msg: str containing a serialized protobuf.
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.pubsub_pb2.PubsubMessage()
msg.data = self.data
for key, value in self.attributes.items():
msg.attributes[key] = value
return msg.SerializeToString()
@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)
return PubsubMessage(msg.data, attributes)
[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(ReadFromPubSub, self).__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):
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(BEAM-3812): 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(_ReadStringsFromPubSub, self).__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(_WriteStringsToPubSub, self).__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(WriteToPubSub, self).__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()
[docs] @staticmethod
def bytes_to_proto_str(element):
# type: (bytes) -> bytes
msg = pubsub.types.pubsub_pb2.PubsubMessage()
msg.data = element
return msg.SerializeToString()
[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(BEAM-3812): 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
class _PubSubSource(dataflow_io.NativeSource):
"""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)
@property
def format(self):
"""Source format name required for remote execution."""
return 'pubsub'
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 reader(self):
raise NotImplementedError
def is_bounded(self):
return False
class _PubSubSink(dataflow_io.NativeSink):
"""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)
@property
def format(self):
"""Sink format name required for remote execution."""
return 'pubsub'
def writer(self):
raise NotImplementedError
[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()