> ## Documentation Index
> Fetch the complete documentation index at: https://docs.streamnative.io/llms.txt
> Use this file to discover all available pages before exploring further.
> The Google Pub/Sub source connector allows you to write messages from Google Pub/Sub to Apache Pulsar.
# Google pubsub source
This connector is available as a built-in connector on StreamNative Cloud.
The [Google Cloud Pub/Sub](https://cloud.google.com/pubsub) source connector feeds data from Google Cloud Pub/Sub topics and writes data to Pulsar topics.
## Quick start
### Prerequisites
The prerequisites for connecting an Google PubSub source connector to external systems include:
1. Create Google PubSub Topic in Google Cloud.
2. Create the [Gcloud ServiceAccount](https://cloud.google.com/iam/docs/service-accounts-create) and create a public key certificate.
3. Create the [Gcloud Role](https://cloud.google.com/iam/docs/creating-custom-roles), ensure the Google Cloud role have the following permissions:
```text theme={null}
- pubsub.subscriptions.consume
- pubsub.subscriptions.create
- pubsub.subscriptions.get
- pubsub.subscriptions.update
- pubsub.topics.attachSubscription
```
4. Grant the service account the above role permissions.
### 1. Create a connector
The following command shows how to use [pulsarctl](https://github.com/streamnative/pulsarctl) to create a `builtin` connector. If you want to create a `non-builtin` connector,
you need to replace `--source-type google-pubsub` with `--archive /path/to/pulsar-io-google-pubsub.nar`. You can find the button to download the `nar` package at the beginning of the document.
If you are a StreamNative Cloud user, you need [set up your environment](https://docs.streamnative.io/docs/connector-setup) first.
```bash theme={null}
pulsarctl sources create \
--source-type google-pubsub \
--name pubsub-source \
--tenant public \
--namespace default \
--destination-topic-name "Your topic name" \
--parallelism 1 \
--source-config \
'{
"pubsubProjectId": "Your google pubsub project Id",
"pubsubTopicId": "Your google pubsub Topic name",
"pubsubCredential": "The escaped and compressed public key certificate you created above"
}'
```
The `--source-config` is the minimum necessary configuration for starting this connector, and it is a JSON string. You need to substitute the relevant parameters with your own.
If you want to configure more parameters, see [Configuration Properties](#configuration-properties) for reference.
You can also choose to use a variety of other tools to create a connector:
* [pulsar-admin](https://pulsar.apache.org/docs/3.1.x/io-use/): The command arguments for `pulsar-admin` are similar to those of `pulsarctl`. You can find an example for [StreamNative Cloud Doc](https://docs.streamnative.io/docs/connector-create#create-a-built-in-connector).
* [RestAPI](https://pulsar.apache.org/source-rest-api/?version=3.1.1): You can find an example for [StreamNative Cloud Doc](https://docs.streamnative.io/docs/connector-create#create-a-built-in-connector).
* [Terraform](https://github.com/hashicorp/terraform): You can find an example for [StreamNative Cloud Doc](https://docs.streamnative.io/docs/connector-create#create-a-built-in-connector).
* [Function Mesh](https://functionmesh.io/docs/connectors/run-connector): The docker image can be found at the beginning of the document.
### 2. Write data to Google PubSub topic
Send some messages to the Google Cloud PubSub using the [gcloud CLI tool](https://cloud.google.com/sdk/docs/install)
```shell theme={null}
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-0"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-1"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-2"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-3"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-4"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-5"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-6"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-7"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-8"
gcloud pubsub topics publish `{{Your PubSub Topic Name}}` --message="my-message-9"
```
### 3. Show data by Pulsar Consumer
If your connector is created on StreamNative Cloud, you need to authenticate your clients. See [Build applications using Pulsar clients](https://docs.streamnative.io/docs/qs-connect#jumpstart-for-beginners) for more information.
```java theme={null}
public static void main(String[] args) {
PulsarClient client = PulsarClient.builder()
.serviceUrl("{{Your Pulsar URL}}")
.build();
Consumer consumer = client.newConsumer(Schema.AUTO_CONSUME())
.topic("{{The topic name that you specified when you created the connector}}")
.subscriptionName(subscription)
.subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
.subscribe();
Consumer consumer = client.newConsumer()
.topic("{{The topic name that you specified when you created the connector}}")
.subscriptionName("test-sub")
.subscriptionInitialPosition(SubscriptionInitialPosition.Earliest)
.subscribe();
for (int i = 0; i < 10; i++) {
Message msg = consumer.receive();
consumer.acknowledge(msg);
System.out.println("Receive message " + new String(msg.getData()));
}
client.close();
}
// output
// Receive message my-message-0
// Receive message my-message-1
// Receive message my-message-2
// Receive message my-message-3
// Receive message my-message-4
// Receive message my-message-5
// Receive message my-message-6
// Receive message my-message-7
// Receive message my-message-8
// Receive message my-message-9
```
## Configuration Properties
Before using the Google PubSub source connector, you need to configure it. This table outlines the properties and the descriptions.
| Name | Type | Required | Sensitive | Default | Description |
| ------------------ | ------ | -------- | --------- | ------------------ | --------------------------------------------------------------------------------------------------------------- |
| `pubsubCredential` | String | true | true | "" (empty string) | The credential (JSON string) for accessing the Google Cloud. It needs to be compressed and escaping before use. |
| `pubsubProjectId` | String | true | false | "" (empty string) | The Google Cloud project ID. |
| `pubsubTopicId` | String | true | false | " " (empty string) | The topic ID. It is used to read messages from or write messages to Google Cloud Pub/Sub topics. |