airflow pubsub 源码
airflow pubsub 代码
文件路径：/airflow/providers/google/cloud/operators/pubsub.py
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"""
This module contains Google PubSub operators.
.. spelling::
MessageStoragePolicy
"""
from __future__ import annotations
from typing import TYPE_CHECKING, Any, Callable, Sequence
from google.api_core.gapic_v1.method import DEFAULT, _MethodDefault
from google.api_core.retry import Retry
from google.cloud.pubsub_v1.types import (
DeadLetterPolicy,
Duration,
ExpirationPolicy,
MessageStoragePolicy,
PushConfig,
ReceivedMessage,
RetryPolicy,
)
from airflow.models import BaseOperator
from airflow.providers.google.cloud.hooks.pubsub import PubSubHook
from airflow.providers.google.cloud.links.pubsub import PubSubSubscriptionLink, PubSubTopicLink
if TYPE_CHECKING:
from airflow.utils.context import Context
class PubSubCreateTopicOperator(BaseOperator):
"""Create a PubSub topic.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PubSubCreateTopicOperator`
By default, if the topic already exists, this operator will
not cause the DAG to fail. ::
with DAG('successful DAG') as dag:
(
PubSubCreateTopicOperator(project_id='my-project', topic='my_new_topic')
>> PubSubCreateTopicOperator(project_id='my-project', topic='my_new_topic')
)
The operator can be configured to fail if the topic already exists. ::
with DAG('failing DAG') as dag:
(
PubSubCreateTopicOperator(project_id='my-project', topic='my_new_topic')
>> PubSubCreateTopicOperator(
project_id='my-project',
topic='my_new_topic',
fail_if_exists=True,
)
)
Both ``project_id`` and ``topic`` are templated so you can use Jinja templating in their values.
:param project_id: Optional, the Google Cloud project ID where the topic will be created.
If set to None or missing, the default project_id from the Google Cloud connection is used.
:param topic: the topic to create. Do not include the
full topic path. In other words, instead of
``projects/{project}/topics/{topic}``, provide only
``{topic}``. (templated)
:param gcp_conn_id: The connection ID to use connecting to
Google Cloud.
:param delegate_to: The account to impersonate using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:param labels: Client-assigned labels; see
https://cloud.google.com/pubsub/docs/labels
:param message_storage_policy: Policy constraining the set
of Google Cloud regions where messages published to
the topic may be stored. If not present, then no constraints
are in effect.
Union[Dict, google.cloud.pubsub_v1.types.MessageStoragePolicy]
:param kms_key_name: The resource name of the Cloud KMS CryptoKey
to be used to protect access to messages published on this topic.
The expected format is
``projects/*/locations/*/keyRings/*/cryptoKeys/*``.
:param retry: (Optional) A retry object used to retry requests.
If None is specified, requests will not be retried.
:param timeout: (Optional) The amount of time, in seconds, to wait for the request
to complete. Note that if retry is specified, the timeout applies to each
individual attempt.
:param metadata: (Optional) Additional metadata that is provided to the method.
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
template_fields: Sequence[str] = (
'project_id',
'topic',
'impersonation_chain',
)
ui_color = '#0273d4'
operator_extra_links = (PubSubTopicLink(),)
def __init__(
self,
*,
topic: str,
project_id: str | None = None,
fail_if_exists: bool = False,
gcp_conn_id: str = 'google_cloud_default',
delegate_to: str | None = None,
labels: dict[str, str] | None = None,
message_storage_policy: dict | MessageStoragePolicy = None,
kms_key_name: str | None = None,
retry: Retry | _MethodDefault = DEFAULT,
timeout: float | None = None,
metadata: Sequence[tuple[str, str]] = (),
impersonation_chain: str | Sequence[str] | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.project_id = project_id
self.topic = topic
self.fail_if_exists = fail_if_exists
self.gcp_conn_id = gcp_conn_id
self.delegate_to = delegate_to
self.labels = labels
self.message_storage_policy = message_storage_policy
self.kms_key_name = kms_key_name
self.retry = retry
self.timeout = timeout
self.metadata = metadata
self.impersonation_chain = impersonation_chain
def execute(self, context: Context) -> None:
hook = PubSubHook(
gcp_conn_id=self.gcp_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
self.log.info("Creating topic %s", self.topic)
hook.create_topic(
project_id=self.project_id,
topic=self.topic,
fail_if_exists=self.fail_if_exists,
labels=self.labels,
message_storage_policy=self.message_storage_policy,
kms_key_name=self.kms_key_name,
retry=self.retry,
timeout=self.timeout,
metadata=self.metadata,
)
self.log.info("Created topic %s", self.topic)
PubSubTopicLink.persist(
context=context,
task_instance=self,
topic_id=self.topic,
project_id=self.project_id or hook.project_id,
)
class PubSubCreateSubscriptionOperator(BaseOperator):
"""Create a PubSub subscription.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PubSubCreateSubscriptionOperator`
By default, the subscription will be created in ``project_id``. If
``subscription_project_id`` is specified and the Google Cloud credentials allow, the
Subscription can be created in a different project from its topic.
By default, if the subscription already exists, this operator will
not cause the DAG to fail. However, the topic must exist in the project. ::
with DAG('successful DAG') as dag:
(
PubSubCreateSubscriptionOperator(
project_id='my-project',
topic='my-topic',
subscription='my-subscription'
)
>> PubSubCreateSubscriptionOperator(
project_id='my-project',
topic='my-topic',
subscription='my-subscription',
)
)
The operator can be configured to fail if the subscription already exists.
::
with DAG('failing DAG') as dag:
(
PubSubCreateSubscriptionOperator(
project_id='my-project',
topic='my-topic',
subscription='my-subscription',
)
>> PubSubCreateSubscriptionOperator(
project_id='my-project',
topic='my-topic',
subscription='my-subscription',
fail_if_exists=True,
)
)
Finally, subscription is not required. If not passed, the operator will
generated a universally unique identifier for the subscription's name. ::
with DAG('DAG') as dag:
PubSubCreateSubscriptionOperator(project_id='my-project', topic='my-topic')
``project_id``, ``topic``, ``subscription``, ``subscription_project_id`` and
``impersonation_chain`` are templated so you can use Jinja templating in their values.
:param project_id: Optional, the Google Cloud project ID where the topic exists.
If set to None or missing, the default project_id from the Google Cloud connection is used.
:param topic: the topic to create. Do not include the
full topic path. In other words, instead of
``projects/{project}/topics/{topic}``, provide only
``{topic}``. (templated)
:param subscription: the Pub/Sub subscription name. If empty, a random
name will be generated using the uuid module
:param subscription_project_id: the Google Cloud project ID where the subscription
will be created. If empty, ``topic_project`` will be used.
:param ack_deadline_secs: Number of seconds that a subscriber has to
acknowledge each message pulled from the subscription
:param gcp_conn_id: The connection ID to use connecting to
Google Cloud.
:param delegate_to: The account to impersonate using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:param push_config: If push delivery is used with this subscription,
this field is used to configure it. An empty ``pushConfig`` signifies
that the subscriber will pull and ack messages using API methods.
:param retain_acked_messages: Indicates whether to retain acknowledged
messages. If true, then messages are not expunged from the subscription's
backlog, even if they are acknowledged, until they fall out of the
``message_retention_duration`` window. This must be true if you would
like to Seek to a timestamp.
:param message_retention_duration: How long to retain unacknowledged messages
in the subscription's backlog, from the moment a message is published. If
``retain_acked_messages`` is true, then this also configures the
retention of acknowledged messages, and thus configures how far back in
time a ``Seek`` can be done. Defaults to 7 days. Cannot be more than 7
days or less than 10 minutes.
:param labels: Client-assigned labels; see
https://cloud.google.com/pubsub/docs/labels
:param enable_message_ordering: If true, messages published with the same
ordering_key in PubsubMessage will be delivered to the subscribers in the order
in which they are received by the Pub/Sub system. Otherwise, they may be
delivered in any order.
:param expiration_policy: A policy that specifies the conditions for this
subscription's expiration. A subscription is considered active as long as any
connected subscriber is successfully consuming messages from the subscription or
is issuing operations on the subscription. If expiration_policy is not set,
a default policy with ttl of 31 days will be used. The minimum allowed value for
expiration_policy.ttl is 1 day.
:param filter_: An expression written in the Cloud Pub/Sub filter language. If
non-empty, then only PubsubMessages whose attributes field matches the filter are
delivered on this subscription. If empty, then no messages are filtered out.
:param dead_letter_policy: A policy that specifies the conditions for dead lettering
messages in this subscription. If dead_letter_policy is not set, dead lettering is
disabled.
:param retry_policy: A policy that specifies how Pub/Sub retries message delivery
for this subscription. If not set, the default retry policy is applied. This
generally implies that messages will be retried as soon as possible for healthy
subscribers. RetryPolicy will be triggered on NACKs or acknowledgement deadline
exceeded events for a given message.
:param retry: (Optional) A retry object used to retry requests.
If None is specified, requests will not be retried.
:param timeout: (Optional) The amount of time, in seconds, to wait for the request
to complete. Note that if retry is specified, the timeout applies to each
individual attempt.
:param metadata: (Optional) Additional metadata that is provided to the method.
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
template_fields: Sequence[str] = (
'project_id',
'topic',
'subscription',
'subscription_project_id',
'impersonation_chain',
)
ui_color = '#0273d4'
operator_extra_links = (PubSubSubscriptionLink(),)
def __init__(
self,
*,
topic: str,
project_id: str | None = None,
subscription: str | None = None,
subscription_project_id: str | None = None,
ack_deadline_secs: int = 10,
fail_if_exists: bool = False,
gcp_conn_id: str = 'google_cloud_default',
delegate_to: str | None = None,
push_config: dict | PushConfig | None = None,
retain_acked_messages: bool | None = None,
message_retention_duration: dict | Duration | None = None,
labels: dict[str, str] | None = None,
enable_message_ordering: bool = False,
expiration_policy: dict | ExpirationPolicy | None = None,
filter_: str | None = None,
dead_letter_policy: dict | DeadLetterPolicy | None = None,
retry_policy: dict | RetryPolicy | None = None,
retry: Retry | _MethodDefault = DEFAULT,
timeout: float | None = None,
metadata: Sequence[tuple[str, str]] = (),
impersonation_chain: str | Sequence[str] | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.project_id = project_id
self.topic = topic
self.subscription = subscription
self.subscription_project_id = subscription_project_id
self.ack_deadline_secs = ack_deadline_secs
self.fail_if_exists = fail_if_exists
self.gcp_conn_id = gcp_conn_id
self.delegate_to = delegate_to
self.push_config = push_config
self.retain_acked_messages = retain_acked_messages
self.message_retention_duration = message_retention_duration
self.labels = labels
self.enable_message_ordering = enable_message_ordering
self.expiration_policy = expiration_policy
self.filter_ = filter_
self.dead_letter_policy = dead_letter_policy
self.retry_policy = retry_policy
self.retry = retry
self.timeout = timeout
self.metadata = metadata
self.impersonation_chain = impersonation_chain
def execute(self, context: Context) -> str:
hook = PubSubHook(
gcp_conn_id=self.gcp_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
self.log.info("Creating subscription for topic %s", self.topic)
result = hook.create_subscription(
project_id=self.project_id,
topic=self.topic,
subscription=self.subscription,
subscription_project_id=self.subscription_project_id,
ack_deadline_secs=self.ack_deadline_secs,
fail_if_exists=self.fail_if_exists,
push_config=self.push_config,
retain_acked_messages=self.retain_acked_messages,
message_retention_duration=self.message_retention_duration,
labels=self.labels,
enable_message_ordering=self.enable_message_ordering,
expiration_policy=self.expiration_policy,
filter_=self.filter_,
dead_letter_policy=self.dead_letter_policy,
retry_policy=self.retry_policy,
retry=self.retry,
timeout=self.timeout,
metadata=self.metadata,
)
self.log.info("Created subscription for topic %s", self.topic)
PubSubSubscriptionLink.persist(
context=context,
task_instance=self,
subscription_id=self.subscription or result, # result returns subscription name
project_id=self.project_id or hook.project_id,
)
return result
class PubSubDeleteTopicOperator(BaseOperator):
"""Delete a PubSub topic.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PubSubDeleteTopicOperator`
By default, if the topic does not exist, this operator will
not cause the DAG to fail. ::
with DAG('successful DAG') as dag:
PubSubDeleteTopicOperator(project_id='my-project', topic='non_existing_topic')
The operator can be configured to fail if the topic does not exist. ::
with DAG('failing DAG') as dag:
PubSubDeleteTopicOperator(
project_id='my-project', topic='non_existing_topic', fail_if_not_exists=True,
)
Both ``project_id`` and ``topic`` are templated so you can use Jinja templating in their values.
:param project_id: Optional, the Google Cloud project ID in which to work (templated).
If set to None or missing, the default project_id from the Google Cloud connection is used.
:param topic: the topic to delete. Do not include the
full topic path. In other words, instead of
``projects/{project}/topics/{topic}``, provide only
``{topic}``. (templated)
:param fail_if_not_exists: If True and the topic does not exist, fail
the task
:param gcp_conn_id: The connection ID to use connecting to
Google Cloud.
:param delegate_to: The account to impersonate using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:param retry: (Optional) A retry object used to retry requests.
If None is specified, requests will not be retried.
:param timeout: (Optional) The amount of time, in seconds, to wait for the request
to complete. Note that if retry is specified, the timeout applies to each
individual attempt.
:param metadata: (Optional) Additional metadata that is provided to the method.
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
template_fields: Sequence[str] = (
'project_id',
'topic',
'impersonation_chain',
)
ui_color = '#cb4335'
def __init__(
self,
*,
topic: str,
project_id: str | None = None,
fail_if_not_exists: bool = False,
gcp_conn_id: str = 'google_cloud_default',
delegate_to: str | None = None,
retry: Retry | _MethodDefault = DEFAULT,
timeout: float | None = None,
metadata: Sequence[tuple[str, str]] = (),
impersonation_chain: str | Sequence[str] | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.project_id = project_id
self.topic = topic
self.fail_if_not_exists = fail_if_not_exists
self.gcp_conn_id = gcp_conn_id
self.delegate_to = delegate_to
self.retry = retry
self.timeout = timeout
self.metadata = metadata
self.impersonation_chain = impersonation_chain
def execute(self, context: Context) -> None:
hook = PubSubHook(
gcp_conn_id=self.gcp_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
self.log.info("Deleting topic %s", self.topic)
hook.delete_topic(
project_id=self.project_id,
topic=self.topic,
fail_if_not_exists=self.fail_if_not_exists,
retry=self.retry,
timeout=self.timeout,
metadata=self.metadata,
)
self.log.info("Deleted topic %s", self.topic)
class PubSubDeleteSubscriptionOperator(BaseOperator):
"""Delete a PubSub subscription.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PubSubDeleteSubscriptionOperator`
By default, if the subscription does not exist, this operator will
not cause the DAG to fail. ::
with DAG('successful DAG') as dag:
PubSubDeleteSubscriptionOperator(project_id='my-project', subscription='non-existing')
The operator can be configured to fail if the subscription already exists.
::
with DAG('failing DAG') as dag:
PubSubDeleteSubscriptionOperator(
project_id='my-project', subscription='non-existing', fail_if_not_exists=True,
)
``project_id``, and ``subscription`` are templated so you can use Jinja templating in their values.
:param project_id: Optional, the Google Cloud project ID in which to work (templated).
If set to None or missing, the default project_id from the Google Cloud connection is used.
:param subscription: the subscription to delete. Do not include the
full subscription path. In other words, instead of
``projects/{project}/subscription/{subscription}``, provide only
``{subscription}``. (templated)
:param fail_if_not_exists: If True and the subscription does not exist,
fail the task
:param gcp_conn_id: The connection ID to use connecting to
Google Cloud.
:param delegate_to: The account to impersonate using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:param retry: (Optional) A retry object used to retry requests.
If None is specified, requests will not be retried.
:param timeout: (Optional) The amount of time, in seconds, to wait for the request
to complete. Note that if retry is specified, the timeout applies to each
individual attempt.
:param metadata: (Optional) Additional metadata that is provided to the method.
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
template_fields: Sequence[str] = (
'project_id',
'subscription',
'impersonation_chain',
)
ui_color = '#cb4335'
def __init__(
self,
*,
subscription: str,
project_id: str | None = None,
fail_if_not_exists: bool = False,
gcp_conn_id: str = 'google_cloud_default',
delegate_to: str | None = None,
retry: Retry | _MethodDefault = DEFAULT,
timeout: float | None = None,
metadata: Sequence[tuple[str, str]] = (),
impersonation_chain: str | Sequence[str] | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.project_id = project_id
self.subscription = subscription
self.fail_if_not_exists = fail_if_not_exists
self.gcp_conn_id = gcp_conn_id
self.delegate_to = delegate_to
self.retry = retry
self.timeout = timeout
self.metadata = metadata
self.impersonation_chain = impersonation_chain
def execute(self, context: Context) -> None:
hook = PubSubHook(
gcp_conn_id=self.gcp_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
self.log.info("Deleting subscription %s", self.subscription)
hook.delete_subscription(
project_id=self.project_id,
subscription=self.subscription,
fail_if_not_exists=self.fail_if_not_exists,
retry=self.retry,
timeout=self.timeout,
metadata=self.metadata,
)
self.log.info("Deleted subscription %s", self.subscription)
class PubSubPublishMessageOperator(BaseOperator):
"""Publish messages to a PubSub topic.
.. seealso::
For more information on how to use this operator, take a look at the guide:
:ref:`howto/operator:PubSubPublishMessageOperator`
Each Task publishes all provided messages to the same topic
in a single Google Cloud project. If the topic does not exist, this
task will fail. ::
m1 = {'data': b'Hello, World!',
'attributes': {'type': 'greeting'}
}
m2 = {'data': b'Knock, knock'}
m3 = {'attributes': {'foo': ''}}
t1 = PubSubPublishMessageOperator(
project_id='my-project',
topic='my_topic',
messages=[m1, m2, m3],
create_topic=True,
dag=dag,
)
``project_id``, ``topic``, and ``messages`` are templated so you can use Jinja templating
in their values.
:param project_id: Optional, the Google Cloud project ID in which to work (templated).
If set to None or missing, the default project_id from the Google Cloud connection is used.
:param topic: the topic to which to publish. Do not include the
full topic path. In other words, instead of
``projects/{project}/topics/{topic}``, provide only
``{topic}``. (templated)
:param messages: a list of messages to be published to the
topic. Each message is a dict with one or more of the
following keys-value mappings:
* 'data': a bytestring (utf-8 encoded)
* 'attributes': {'key1': 'value1', ...}
Each message must contain at least a non-empty 'data' value
or an attribute dict with at least one key (templated). See
https://cloud.google.com/pubsub/docs/reference/rest/v1/PubsubMessage
:param gcp_conn_id: The connection ID to use connecting to
Google Cloud.
:param delegate_to: The account to impersonate using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
template_fields: Sequence[str] = (
'project_id',
'topic',
'messages',
'impersonation_chain',
)
ui_color = '#0273d4'
def __init__(
self,
*,
topic: str,
messages: list,
project_id: str | None = None,
gcp_conn_id: str = 'google_cloud_default',
delegate_to: str | None = None,
impersonation_chain: str | Sequence[str] | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.project_id = project_id
self.topic = topic
self.messages = messages
self.gcp_conn_id = gcp_conn_id
self.delegate_to = delegate_to
self.impersonation_chain = impersonation_chain
def execute(self, context: Context) -> None:
hook = PubSubHook(
gcp_conn_id=self.gcp_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
self.log.info("Publishing to topic %s", self.topic)
hook.publish(project_id=self.project_id, topic=self.topic, messages=self.messages)
self.log.info("Published to topic %s", self.topic)
class PubSubPullOperator(BaseOperator):
"""Pulls messages from a PubSub subscription and passes them through XCom.
If the queue is empty, returns empty list - never waits for messages.
If you do need to wait, please use :class:`airflow.providers.google.cloud.sensors.PubSubPullSensor`
instead.
.. seealso::
For more information on how to use this operator and the PubSubPullSensor, take a look at the guide:
:ref:`howto/operator:PubSubPullSensor`
This operator will pull up to ``max_messages`` messages from the
specified PubSub subscription. When the subscription returns messages,
the messages will be returned immediately from the operator and passed through XCom for downstream tasks.
If ``ack_messages`` is set to True, messages will be immediately
acknowledged before being returned, otherwise, downstream tasks will be
responsible for acknowledging them.
``project_id `` and ``subscription`` are templated so you can use Jinja templating in their values.
:param project_id: the Google Cloud project ID for the subscription (templated)
:param subscription: the Pub/Sub subscription name. Do not include the
full subscription path.
:param max_messages: The maximum number of messages to retrieve per
PubSub pull request
:param ack_messages: If True, each message will be acknowledged
immediately rather than by any downstream tasks
:param gcp_conn_id: The connection ID to use connecting to
Google Cloud.
:param delegate_to: The account to impersonate using domain-wide delegation of authority,
if any. For this to work, the service account making the request must have
domain-wide delegation enabled.
:param messages_callback: (Optional) Callback to process received messages.
It's return value will be saved to XCom.
If you are pulling large messages, you probably want to provide a custom callback.
If not provided, the default implementation will convert `ReceivedMessage` objects
into JSON-serializable dicts using `google.protobuf.json_format.MessageToDict` function.
:param impersonation_chain: Optional service account to impersonate using short-term
credentials, or chained list of accounts required to get the access_token
of the last account in the list, which will be impersonated in the request.
If set as a string, the account must grant the originating account
the Service Account Token Creator IAM role.
If set as a sequence, the identities from the list must grant
Service Account Token Creator IAM role to the directly preceding identity, with first
account from the list granting this role to the originating account (templated).
"""
template_fields: Sequence[str] = (
'project_id',
'subscription',
'impersonation_chain',
)
def __init__(
self,
*,
project_id: str,
subscription: str,
max_messages: int = 5,
ack_messages: bool = False,
messages_callback: Callable[[list[ReceivedMessage], Context], Any] | None = None,
gcp_conn_id: str = 'google_cloud_default',
delegate_to: str | None = None,
impersonation_chain: str | Sequence[str] | None = None,
**kwargs,
) -> None:
super().__init__(**kwargs)
self.gcp_conn_id = gcp_conn_id
self.delegate_to = delegate_to
self.project_id = project_id
self.subscription = subscription
self.max_messages = max_messages
self.ack_messages = ack_messages
self.messages_callback = messages_callback
self.impersonation_chain = impersonation_chain
def execute(self, context: Context) -> list:
hook = PubSubHook(
gcp_conn_id=self.gcp_conn_id,
delegate_to=self.delegate_to,
impersonation_chain=self.impersonation_chain,
)
pulled_messages = hook.pull(
project_id=self.project_id,
subscription=self.subscription,
max_messages=self.max_messages,
return_immediately=True,
)
handle_messages = self.messages_callback or self._default_message_callback
ret = handle_messages(pulled_messages, context)
if pulled_messages and self.ack_messages:
hook.acknowledge(
project_id=self.project_id,
subscription=self.subscription,
messages=pulled_messages,
)
return ret
def _default_message_callback(
self,
pulled_messages: list[ReceivedMessage],
context: Context,
) -> list:
"""
This method can be overridden by subclasses or by `messages_callback` constructor argument.
This default implementation converts `ReceivedMessage` objects into JSON-serializable dicts.
:param pulled_messages: messages received from the topic.
:param context: same as in `execute`
:return: value to be saved to XCom.
"""
messages_json = [ReceivedMessage.to_dict(m) for m in pulled_messages]
return messages_json
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