Subscriptions#

Define API Subscriptions.

class google.cloud.pubsub.subscription.Subscription(name, topic=None, ack_deadline=None, push_endpoint=None, client=None)[source]#

Bases: object

Subscriptions receive messages published to their topics.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions

Parameters:

name (string) – the name of the subscription.
topic (google.cloud.pubsub.topic.Topic or NoneType) – the topic to which the subscription belongs; if None, the subscription’s topic has been deleted.
ack_deadline (int) – the deadline (in seconds) by which messages pulled from the back-end must be acknowledged.
push_endpoint (string) – URL to which messages will be pushed by the back-end. If not set, the application must pull messages.
client (Client or NoneType) – the client to use. If not passed, falls back to the client stored on the topic.

classmethod from_api_repr(resource, client, topics=None)[source]#

Factory: construct a topic given its API representation

Parameters:	resource (dict) – topic resource representation returned from the API. client (`google.cloud.pubsub.client.Client`) – Client which holds credentials and project configuration for a topic. topics (dict or None) – A mapping of topic names -> topics. If not passed, the subscription will have a newly-created topic.
Return type:	`google.cloud.pubsub.subscription.Subscription`
Returns:	Subscription parsed from `resource`.

project#: Project bound to the subscription.

full_name#: Fully-qualified name used in subscription APIs

path#: URL path for the subscription’s APIs

auto_ack(return_immediately=False, max_messages=1, client=None)[source]#

AutoAck factory

Parameters:	return_immediately (boolean) – passed through to `Subscription.pull()` max_messages (int) – passed through to `Subscription.pull()` client (`Client` or `NoneType`) – passed through to `Subscription.pull()` and `Subscription.acknowledge()`.
Return type:	`AutoAck`
Returns:	the instance created for the given `ack_id` and `message`

create(client=None)[source]#

API call: create the subscription via a PUT request

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/create

Example:

    subscription = topic.subscription(SUB_NAME)
    subscription.create()                               # API request

Parameters:	client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.

exists(client=None)[source]#

API call: test existence of the subscription via a GET request

See https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/get

Example:

    assert subscription.exists()                        # API request

Parameters:	client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.
Return type:	bool
Returns:	Boolean indicating existence of the subscription.

reload(client=None)[source]#

API call: sync local subscription configuration via a GET request

See https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/get

Example:

    subscription.reload()                               # API request

Parameters:	client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.

delete(client=None)[source]#

API call: delete the subscription via a DELETE request.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/delete

Example:

    subscription.delete()                               # API request

Parameters:	client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.

modify_push_configuration(push_endpoint, client=None)[source]#

API call: update the push endpoint for the subscription.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/modifyPushConfig

Example:

    subscription.modify_push_configuration(push_endpoint=None)  # API request

    subscription.modify_push_configuration(
        push_endpoint=PUSH_URL)                                 # API request

Parameters:	push_endpoint (string) – URL to which messages will be pushed by the back-end. If None, the application must pull messages. client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.

pull(return_immediately=False, max_messages=1, client=None)[source]#

API call: retrieve messages for the subscription.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/pull

Example:

    pulled = subscription.pull(max_messages=2)

Parameters:	return_immediately (boolean) – if True, the back-end returns even if no messages are available; if False, the API call blocks until one or more messages are available. max_messages (int) – the maximum number of messages to return. client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.
Return type:	list of (ack_id, message) tuples
Returns:	sequence of tuples: `ack_id` is the ID to be used in a subsequent call to `acknowledge()`, and `message` is an instance of `Message`.

acknowledge(ack_ids, client=None)[source]#

API call: acknowledge retrieved messages for the subscription.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/acknowledge

Example:

    for ack_id, message in pulled:
        try:
            do_something_with(message)
        except ApplicationException as e:
            log_exception(e)
        else:
            subscription.acknowledge([ack_id])

Parameters:	ack_ids (list of string) – ack IDs of messages being acknowledged client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.

modify_ack_deadline(ack_ids, ack_deadline, client=None)[source]#

API call: update acknowledgement deadline for a retrieved message.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/modifyAckDeadline

Parameters:	ack_ids (list of string) – ack IDs of messages being updated ack_deadline (int) – new deadline for the message, in seconds client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.

get_iam_policy(client=None)[source]#

Fetch the IAM policy for the subscription.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/getIamPolicy

Example:

    policy = subscription.get_iam_policy()             # API request

Parameters:	client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.
Return type:	`google.cloud.pubsub.iam.Policy`
Returns:	policy created from the resource returned by the `getIamPolicy` API request.

set_iam_policy(policy, client=None)[source]#

Update the IAM policy for the subscription.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/setIamPolicy

Example:

    ALL_USERS = policy.all_users()
    policy.viewers.add(ALL_USERS)
    LOGS_GROUP = policy.group('cloud-logs@google.com')
    policy.editors.add(LOGS_GROUP)
    new_policy = subscription.set_iam_policy(policy)   # API request

Parameters:	policy (`google.cloud.pubsub.iam.Policy`) – the new policy, typically fetched via `get_iam_policy()` and updated in place. client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.
Return type:	`google.cloud.pubsub.iam.Policy`
Returns:	updated policy created from the resource returned by the `setIamPolicy` API request.

check_iam_permissions(permissions, client=None)[source]#

Verify permissions allowed for the current user.

See: https://cloud.google.com/pubsub/docs/reference/rest/v1/projects.subscriptions/testIamPermissions

Example:

    from google.cloud.pubsub.iam import OWNER_ROLE, EDITOR_ROLE, VIEWER_ROLE
    TO_CHECK = [OWNER_ROLE, EDITOR_ROLE, VIEWER_ROLE]
    ALLOWED = subscription.check_iam_permissions(TO_CHECK)
    assert set(ALLOWED) == set(TO_CHECK)

Parameters:	permissions (list of string) – list of permissions to be tested client (`Client` or `NoneType`) – the client to use. If not passed, falls back to the `client` stored on the current subscription’s topic.
Return type:	sequence of string
Returns:	subset of `permissions` allowed by current IAM policy.

class google.cloud.pubsub.subscription.AutoAck(subscription, return_immediately=False, max_messages=1, client=None)[source]#

Bases: dict

Wrapper for Subscription.pull() results.

Mapping, tracks messages still-to-be-acknowledged.

When used as a context manager, acknowledges all messages still in the mapping on __exit__. When processing the pulled messages, application code MUST delete messages from the AutoAck mapping which are not successfully processed, e.g.:

Parameters:	subscription (`Subscription`) – subscription to be pulled. return_immediately (boolean) – passed through to `Subscription.pull()` max_messages (int) – passed through to `Subscription.pull()` client (`Client` or `NoneType`) – passed through to `Subscription.pull()` and `Subscription.acknowledge()`.