Cloud Pub/Sub API Connector Overview

The Workflows connector defines the built-in functions that can be used to access other Google Cloud products within a workflow.

This page provides an overview of the individual connector. There is no need to import or load connector libraries in a workflow—connectors work out of the box when used in a call step.

Cloud Pub/Sub API

Provides reliable, many-to-many, asynchronous messaging between applications. To learn more, see the Cloud Pub/Sub API documentation.

This connector supports Pub/Sub operations, including publishing messages. You can also trigger an execution of a workflow using messages published to a Pub/Sub topic.

Cloud Pub/Sub connector sample

YAML

# This workflow demonstrates how to use the Cloud Pub/Sub connector.
# The workflow creates a Pub/Sub topic, a new subscription to that new topic, publishes a new message to
# the topic, pulls the message from the subscription, and then deletes both
# the subscription and the topic.
# Expected successful output: "SUCCESS"

- init:
    assign:
      - project: ${sys.get_env("GOOGLE_CLOUD_PROJECT_ID")}
      - topic: "[fill in a Pubsub topic name]"
      - subscription: "[fill in a Pubsub subscription name]"
      - message: {"hello": "world"}  # An object used as a secret.
      - base64Msg: ${base64.encode(json.encode(message))}
- create_topic:
    call: googleapis.pubsub.v1.projects.topics.create
    args:
      name: ${"projects/" + project + "/topics/" + topic}
- create_subscription_to_topic:
    call: googleapis.pubsub.v1.projects.subscriptions.create
    args:
      name: ${"projects/" + project + "/subscriptions/" + subscription}
      body:
        name: ${"projects/" + project + "/subscriptions/" + subscription}
        topic: ${"projects/" + project + "/topics/" + topic}
- publish_message_to_topic:
    call: googleapis.pubsub.v1.projects.topics.publish
    args:
      topic: ${"projects/" + project + "/topics/" + topic}
      body:
        messages:
          - data: ${base64Msg}
- pull_message:
    call: googleapis.pubsub.v1.projects.subscriptions.pull
    args:
      subscription: ${"projects/" + project + "/subscriptions/" + subscription}
      body:
        maxMessages: 1
    result: m
- check_message:
    switch:
      - condition: ${m.receivedMessages[0].message.data != base64Msg}
        next: failed
- delete_subscription:
    call: googleapis.pubsub.v1.projects.subscriptions.delete
    args:
      subscription: ${"projects/" + project + "/subscriptions/" + subscription}
- delete_topic:
    call: googleapis.pubsub.v1.projects.topics.delete
    args:
      topic: ${"projects/" + project + "/topics/" + topic}
- the_end:
    return: "SUCCESS"
- failed:
    raise: ${"got data:" + m.receivedMessages[0].message.data + " want data:" + base64Msg}

JSON

[
  {
    "init": {
      "assign": [
        {
          "project": "${sys.get_env(\"GOOGLE_CLOUD_PROJECT_ID\")}"
        },
        {
          "topic": "[fill in a Pubsub topic name]"
        },
        {
          "subscription": "[fill in a Pubsub subscription name]"
        },
        {
          "message": {
            "hello": "world"
          }
        },
        {
          "base64Msg": "${base64.encode(json.encode(message))}"
        }
      ]
    }
  },
  {
    "create_topic": {
      "call": "googleapis.pubsub.v1.projects.topics.create",
      "args": {
        "name": "${\"projects/\" + project + \"/topics/\" + topic}"
      }
    }
  },
  {
    "create_subscription_to_topic": {
      "call": "googleapis.pubsub.v1.projects.subscriptions.create",
      "args": {
        "name": "${\"projects/\" + project + \"/subscriptions/\" + subscription}",
        "body": {
          "name": "${\"projects/\" + project + \"/subscriptions/\" + subscription}",
          "topic": "${\"projects/\" + project + \"/topics/\" + topic}"
        }
      }
    }
  },
  {
    "publish_message_to_topic": {
      "call": "googleapis.pubsub.v1.projects.topics.publish",
      "args": {
        "topic": "${\"projects/\" + project + \"/topics/\" + topic}",
        "body": {
          "messages": [
            {
              "data": "${base64Msg}"
            }
          ]
        }
      }
    }
  },
  {
    "pull_message": {
      "call": "googleapis.pubsub.v1.projects.subscriptions.pull",
      "args": {
        "subscription": "${\"projects/\" + project + \"/subscriptions/\" + subscription}",
        "body": {
          "maxMessages": 1
        }
      },
      "result": "m"
    }
  },
  {
    "check_message": {
      "switch": [
        {
          "condition": "${m.receivedMessages[0].message.data != base64Msg}",
          "next": "failed"
        }
      ]
    }
  },
  {
    "delete_subscription": {
      "call": "googleapis.pubsub.v1.projects.subscriptions.delete",
      "args": {
        "subscription": "${\"projects/\" + project + \"/subscriptions/\" + subscription}"
      }
    }
  },
  {
    "delete_topic": {
      "call": "googleapis.pubsub.v1.projects.topics.delete",
      "args": {
        "topic": "${\"projects/\" + project + \"/topics/\" + topic}"
      }
    }
  },
  {
    "the_end": {
      "return": "SUCCESS"
    }
  },
  {
    "failed": {
      "raise": "${\"got data:\" + m.receivedMessages[0].message.data + \" want data:\" + base64Msg}"
    }
  }
]

Module: googleapis.pubsub.v1.projects.schemas

Functions
`create`	Creates a schema.
`delete`	Deletes a schema.
`get`	Gets a schema.
`list`	Lists schemas in a project.
`validate`	Validates a schema.
`validateMessage`	Validates a message against a schema.

Module: googleapis.pubsub.v1.projects.snapshots

Functions
`create`	Creates a snapshot from the requested subscription. Snapshots are used in Seek operations, which allow you to manage message acknowledgments in bulk. That is, you can set the acknowledgment state of messages in an existing subscription to the state captured by a snapshot. If the snapshot already exists, returns `ALREADY_EXISTS`. If the requested subscription doesn't exist, returns `NOT_FOUND`. If the backlog in the subscription is too old -- and the resulting snapshot would expire in less than 1 hour -- then `FAILED_PRECONDITION` is returned. See also the `Snapshot.expire_time` field. If the name is not provided in the request, the server will assign a random name for this snapshot on the same project as the subscription, conforming to the resource name format. The generated name is populated in the returned Snapshot object. Note that for REST API requests, you must specify a name in the request.
`delete`	Removes an existing snapshot. Snapshots are used in Seek operations, which allow you to manage message acknowledgments in bulk. That is, you can set the acknowledgment state of messages in an existing subscription to the state captured by a snapshot. When the snapshot is deleted, all messages retained in the snapshot are immediately dropped. After a snapshot is deleted, a new one may be created with the same name, but the new one has no association with the old snapshot or its subscription, unless the same subscription is specified.
`getIamPolicy`	Gets the access control policy for a resource. Returns an empty policy if the resource exists and does not have a policy set.
`list`	Lists the existing snapshots. Snapshots are used in Seek operations, which allow you to manage message acknowledgments in bulk. That is, you can set the acknowledgment state of messages in an existing subscription to the state captured by a snapshot.
`patch`	Updates an existing snapshot. Snapshots are used in Seek operations, which allow you to manage message acknowledgments in bulk. That is, you can set the acknowledgment state of messages in an existing subscription to the state captured by a snapshot.
`setIamPolicy`	Sets the access control policy on the specified resource. Replaces any existing policy. Can return `NOT_FOUND`, `INVALID_ARGUMENT`, and `PERMISSION_DENIED` errors.
`testIamPermissions`	Returns permissions that a caller has on the specified resource. If the resource does not exist, this will return an empty set of permissions, not a `NOT_FOUND` error. Note: This operation is designed to be used for building permission-aware UIs and command-line tools, not for authorization checking. This operation may "fail open" without warning.

Module: googleapis.pubsub.v1.projects.subscriptions

Functions
`acknowledge`	Acknowledges the messages associated with the `ack_ids` in the `AcknowledgeRequest`. The Pub/Sub system can remove the relevant messages from the subscription. Acknowledging a message whose ack deadline has expired may succeed, but such a message may be redelivered later. Acknowledging a message more than once will not result in an error.
`create`	Creates a subscription to a given topic. See the resource name rules. If the subscription already exists, returns `ALREADY_EXISTS`. If the corresponding topic doesn't exist, returns `NOT_FOUND`. If the name is not provided in the request, the server will assign a random name for this subscription on the same project as the topic, conforming to the resource name format. The generated name is populated in the returned Subscription object. Note that for REST API requests, you must specify a name in the request.
`delete`	Deletes an existing subscription. All messages retained in the subscription are immediately dropped. Calls to `Pull` after deletion will return `NOT_FOUND`. After a subscription is deleted, a new one may be created with the same name, but the new one has no association with the old subscription or its topic unless the same topic is specified.
`detach`	Detaches a subscription from this topic. All messages retained in the subscription are dropped. Subsequent `Pull` and `StreamingPull` requests will return FAILED_PRECONDITION. If the subscription is a push subscription, pushes to the endpoint will stop.
`get`	Gets the configuration details of a subscription.
`getIamPolicy`	Gets the access control policy for a resource. Returns an empty policy if the resource exists and does not have a policy set.
`list`	Lists matching subscriptions.
`modifyAckDeadline`	Modifies the ack deadline for a specific message. This method is useful to indicate that more time is needed to process a message by the subscriber, or to make the message available for redelivery if the processing was interrupted. Note that this does not modify the subscription-level `ackDeadlineSeconds` used for subsequent messages.
`modifyPushConfig`	Modifies the `PushConfig` for a specified subscription. This may be used to change a push subscription to a pull one (signified by an empty `PushConfig`) or vice versa, or change the endpoint URL and other attributes of a push subscription. Messages will accumulate for delivery continuously through the call regardless of changes to the `PushConfig`.
`patch`	Updates an existing subscription. Note that certain properties of a subscription, such as its topic, are not modifiable.
`pull`	Pulls messages from the server. The server may return `UNAVAILABLE` if there are too many concurrent pull requests pending for the given subscription.
`seek`	Seeks an existing subscription to a point in time or to a given snapshot, whichever is provided in the request. Snapshots are used in Seek operations, which allow you to manage message acknowledgments in bulk. That is, you can set the acknowledgment state of messages in an existing subscription to the state captured by a snapshot. Note that both the subscription and the snapshot must be on the same topic.
`setIamPolicy`	Sets the access control policy on the specified resource. Replaces any existing policy. Can return `NOT_FOUND`, `INVALID_ARGUMENT`, and `PERMISSION_DENIED` errors.
`testIamPermissions`	Returns permissions that a caller has on the specified resource. If the resource does not exist, this will return an empty set of permissions, not a `NOT_FOUND` error. Note: This operation is designed to be used for building permission-aware UIs and command-line tools, not for authorization checking. This operation may "fail open" without warning.

Module: googleapis.pubsub.v1.projects.topics

Functions
`create`	Creates the given topic with the given name. See the resource name rules.
`delete`	Deletes the topic with the given name. Returns `NOT_FOUND` if the topic does not exist. After a topic is deleted, a new topic may be created with the same name; this is an entirely new topic with none of the old configuration or subscriptions. Existing subscriptions to this topic are not deleted, but their `topic` field is set to `_deleted-topic_`.
`get`	Gets the configuration of a topic.
`getIamPolicy`	Gets the access control policy for a resource. Returns an empty policy if the resource exists and does not have a policy set.
`list`	Lists matching topics.
`patch`	Updates an existing topic. Note that certain properties of a topic are not modifiable.
`publish`	Adds one or more messages to the topic. Returns `NOT_FOUND` if the topic does not exist.
`setIamPolicy`	Sets the access control policy on the specified resource. Replaces any existing policy. Can return `NOT_FOUND`, `INVALID_ARGUMENT`, and `PERMISSION_DENIED` errors.
`testIamPermissions`	Returns permissions that a caller has on the specified resource. If the resource does not exist, this will return an empty set of permissions, not a `NOT_FOUND` error. Note: This operation is designed to be used for building permission-aware UIs and command-line tools, not for authorization checking. This operation may "fail open" without warning.

Module: googleapis.pubsub.v1.projects.topics.snapshots

Functions
`list`	Lists the names of the snapshots on this topic. Snapshots are used in Seek operations, which allow you to manage message acknowledgments in bulk. That is, you can set the acknowledgment state of messages in an existing subscription to the state captured by a snapshot.

Module: googleapis.pubsub.v1.projects.topics.subscriptions

Functions
`list`	Lists the names of the attached subscriptions on this topic.