airflow.providers.google.cloud.sensors.pubsub

This module contains a Google PubSub sensor.

Module Contents

class airflow.providers.google.cloud.sensors.pubsub.PubSubPullSensor(*, project_id: str, subscription: str, max_messages: int = 5, return_immediately: bool = True, ack_messages: bool = False, gcp_conn_id: str = 'google_cloud_default', messages_callback: Optional[Callable[[List[ReceivedMessage], Dict[str, Any]], Any]] = None, delegate_to: Optional[str] = None, project: Optional[str] = None, impersonation_chain: Optional[Union[str, Sequence[str]]] = None, **kwargs)[source]

Bases: airflow.sensors.base.BaseSensorOperator

Pulls messages from a PubSub subscription and passes them through XCom. Always waits for at least one message to be returned from the subscription.

See also

For more information on how to use this operator, take a look at the guide: Pulling messages from a PubSub subscription

See also

If you don’t want to wait for at least one message to come, use Operator instead: PubSubPullOperator

This sensor operator will pull up to max_messages messages from the specified PubSub subscription. When the subscription returns messages, the poke method’s criteria will be fulfilled and the messages will be returned 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 and subscription are templated so you can use variables in them.

Parameters

  • project (str) – the Google Cloud project ID for the subscription (templated)

  • subscription (str) – the Pub/Sub subscription name. Do not include the full subscription path.

  • max_messages (int) – The maximum number of messages to retrieve per PubSub pull request

  • return_immediately (bool) –

    (Deprecated) This is an underlying PubSub API implementation detail. It has no real effect on Sensor behaviour other than some internal wait time before retrying on empty queue. The Sensor task will (by definition) always wait for a message, regardless of this argument value.

    If you want a non-blocking task that does not to wait for messages, please use PubSubPullOperator instead.

  • ack_messages (bool) – If True, each message will be acknowledged immediately rather than by any downstream tasks

  • gcp_conn_id (str) – The connection ID to use connecting to Google Cloud.

  • delegate_to (str) – 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.

  • messages_callback (Optional[Callable[[List[ReceivedMessage], Dict[str, Any]], Any]]) – (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.

  • impersonation_chain (Union[str, Sequence[str]]) – 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 = ['project_id', 'subscription', 'impersonation_chain'][source]
ui_color = #ff7f50[source]
execute(self, context: dict)[source]

Overridden to allow messages to be passed

poke(self, context: dict)[source]
_default_message_callback(self, pulled_messages: List[ReceivedMessage], context: Dict[str, Any])[source]

This method can be overridden by subclasses or by messages_callback constructor argument. This default implementation converts ReceivedMessage objects into JSON-serializable dicts.

Parameters

  • pulled_messages (List[ReceivedMessage]) – messages received from the topic.

  • context – same as in execute

Returns

value to be saved to XCom.

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