REST Resource: projects.subscriptions

Resource: Subscription

A subscription resource.

JSON representation
{
  "name": string,
  "topic": string,
  "pushConfig": {
    object (PushConfig)
  },
  "ackDeadlineSeconds": integer,
  "retainAckedMessages": boolean,
  "messageRetentionDuration": string,
  "labels": {
    string: string,
    ...
  },
  "enableMessageOrdering": boolean,
  "expirationPolicy": {
    object (ExpirationPolicy)
  },
  "filter": string,
  "deadLetterPolicy": {
    object (DeadLetterPolicy)
  },
  "retryPolicy": {
    object (RetryPolicy)
  }
}
Fields
name

string

Required. Name of the subscription. Format is projects/{project}/subscriptions/{sub}.

topic

string

Required. The name of the topic from which this subscription is receiving messages. Format is projects/{project}/topics/{topic}. The value of this field will be _deleted-topic_ if the topic has been deleted.

pushConfig

object (PushConfig)

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.

ackDeadlineSeconds

integer

The approximate amount of time (on a best-effort basis) Pub/Sub waits for the subscriber to acknowledge receipt before resending the message. In the interval after the message is delivered and before it is acknowledged, it is considered to be outstanding. During that time period, the message will not be redelivered (on a best-effort basis).

For pull subscriptions, this value is used as the initial value for the ack deadline. To override this value for a given message, call subscriptions.modifyAckDeadline with the corresponding ackId if using non-streaming pull or send the ackId in a StreamingModifyAckDeadlineRequest if using streaming pull. The minimum custom deadline you can specify is 10 seconds. The maximum custom deadline you can specify is 600 seconds (10 minutes). If this parameter is 0, a default value of 10 seconds is used.

For push delivery, this value is also used to set the request timeout for the call to the push endpoint.

If the subscriber never acknowledges the message, the Pub/Sub system will eventually redeliver the message.

retainAckedMessages

boolean

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 messageRetentionDuration window. This must be true if you would like to subscriptions.seek to a timestamp.

messageRetentionDuration

string (Duration format)

How long to retain unacknowledged messages in the subscription's backlog, from the moment a message is published. If retainAckedMessages is true, then this also configures the retention of acknowledged messages, and thus configures how far back in time a subscriptions.seek can be done. Defaults to 7 days. Cannot be more than 7 days or less than 10 minutes.

A duration in seconds with up to nine fractional digits, terminated by 's'. Example: "3.5s".

labels

map (key: string, value: string)

See Creating and managing labels.

An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.

enableMessageOrdering

boolean

If true, messages published with the same orderingKey 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.

expirationPolicy

object (ExpirationPolicy)

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 expirationPolicy is not set, a default policy with ttl of 31 days will be used. The minimum allowed value for expirationPolicy.ttl is 1 day.

filter

string

An expression written in the 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.

deadLetterPolicy

object (DeadLetterPolicy)

A policy that specifies the conditions for dead lettering messages in this subscription. If deadLetterPolicy is not set, dead lettering is disabled.

The Cloud Pub/Sub service account associated with this subscriptions's parent project (i.e., service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have permission to subscriptions.acknowledge() messages on this subscription.

retryPolicy

object (RetryPolicy)

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.

PushConfig

Configuration for a push delivery endpoint.

JSON representation
{
  "pushEndpoint": string,
  "attributes": {
    string: string,
    ...
  },
  "oidcToken": {
    object (OidcToken)
  }
}
Fields
pushEndpoint

string

A URL locating the endpoint to which messages should be pushed. For example, a Webhook endpoint might use https://example.com/push.

attributes

map (key: string, value: string)

Endpoint configuration attributes that can be used to control different aspects of the message delivery.

The only currently supported attribute is x-goog-version, which you can use to change the format of the pushed message. This attribute indicates the version of the data expected by the endpoint. This controls the shape of the pushed message (i.e., its fields and metadata).

If not present during the subscriptions.create call, it will default to the version of the Pub/Sub API used to make such call. If not present in a subscriptions.modifyPushConfig call, its value will not be changed. subscriptions.get calls will always return a valid version, even if the subscription was created without this attribute.

The only supported values for the x-goog-version attribute are:

For example:

attributes { "x-goog-version": "v1" } 

An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.

oidcToken

object (OidcToken)

If specified, Pub/Sub will generate and attach an OIDC JWT token as an Authorization header in the HTTP request for every pushed message.

OidcToken

Contains information needed for generating an OpenID Connect token.

JSON representation
{
  "serviceAccountEmail": string,
  "audience": string
}
Fields
serviceAccountEmail

string

Service account email to be used for generating the OIDC token. The caller (for subscriptions.create, subscriptions.patch, and subscriptions.modifyPushConfig RPCs) must have the iam.serviceAccounts.actAs permission for the service account.

audience

string

Audience to be used when generating OIDC token. The audience claim identifies the recipients that the JWT is intended for. The audience value is a single case-sensitive string. Having multiple values (array) for the audience field is not supported. More info about the OIDC JWT token audience here: https://tools.ietf.org/html/rfc7519#section-4.1.3 Note: if not specified, the Push endpoint URL will be used.

ExpirationPolicy

A policy that specifies the conditions for resource expiration (i.e., automatic resource deletion).

JSON representation
{
  "ttl": string
}
Fields
ttl

string (Duration format)

Specifies the "time-to-live" duration for an associated resource. The resource expires if it is not active for a period of ttl. The definition of "activity" depends on the type of the associated resource. The minimum and maximum allowed values for ttl depend on the type of the associated resource, as well. If ttl is not set, the associated resource never expires.

A duration in seconds with up to nine fractional digits, terminated by 's'. Example: "3.5s".

DeadLetterPolicy

Dead lettering is done on a best effort basis. The same message might be dead lettered multiple times.

If validation on any of the fields fails at subscription creation/updation, the create/update subscription request will fail.

JSON representation
{
  "deadLetterTopic": string,
  "maxDeliveryAttempts": integer
}
Fields
deadLetterTopic

string

The name of the topic to which dead letter messages should be published. Format is projects/{project}/topics/{topic}.The Cloud Pub/Sub service account associated with the enclosing subscription's parent project (i.e., service-{project_number}@gcp-sa-pubsub.iam.gserviceaccount.com) must have permission to topics.publish() to this topic.

The operation will fail if the topic does not exist. Users should ensure that there is a subscription attached to this topic since messages published to a topic with no subscriptions are lost.

maxDeliveryAttempts

integer

The maximum number of delivery attempts for any message. The value must be between 5 and 100.

The number of delivery attempts is defined as 1 + (the sum of number of NACKs and number of times the acknowledgement deadline has been exceeded for the message).

A NACK is any call to subscriptions.modifyAckDeadline with a 0 deadline. Note that client libraries may automatically extend ack_deadlines.

This field will be honored on a best effort basis.

If this parameter is 0, a default value of 5 is used.

RetryPolicy

A policy that specifies how Cloud Pub/Sub retries message delivery.

Retry delay will be exponential based on provided minimum and maximum backoffs. https://en.wikipedia.org/wiki/Exponential_backoff.

RetryPolicy will be triggered on NACKs or acknowledgement deadline exceeded events for a given message.

Retry Policy is implemented on a best effort basis. At times, the delay between consecutive deliveries may not match the configuration. That is, delay can be more or less than configured backoff.

JSON representation
{
  "minimumBackoff": string,
  "maximumBackoff": string
}
Fields
minimumBackoff

string (Duration format)

The minimum delay between consecutive deliveries of a given message. Value should be between 0 and 600 seconds. Defaults to 10 seconds.

A duration in seconds with up to nine fractional digits, terminated by 's'. Example: "3.5s".

maximumBackoff

string (Duration format)

The maximum delay between consecutive deliveries of a given message. Value should be between 0 and 600 seconds. Defaults to 600 seconds.

A duration in seconds with up to nine fractional digits, terminated by 's'. Example: "3.5s".

Methods

acknowledge

Acknowledges the messages associated with the ack_ids in the AcknowledgeRequest.

create

Creates a subscription to a given topic.

delete

Deletes an existing subscription.

detach

Detaches a subscription from this topic.

get

Gets the configuration details of a subscription.

getIamPolicy

Gets the access control policy for a resource.

list

Lists matching subscriptions.

modifyAckDeadline

Modifies the ack deadline for a specific message.

modifyPushConfig

Modifies the PushConfig for a specified subscription.

patch

Updates an existing subscription.

pull

Pulls messages from the server.

seek

Seeks an existing subscription to a point in time or to a given snapshot, whichever is provided in the request.

setIamPolicy

Sets the access control policy on the specified resource.

testIamPermissions

Returns permissions that a caller has on the specified resource.