Error 403: Error sending test message to Cloud PubSub: User not authorized to perform this action

Question

I want to set up a push notification watch but I receive an error response. What authorization I need?

Request:

// Google API
$client = getClient();

// POST request    
$ch = curl_init('https://www.googleapis.com/gmail/v1/users/me/watch');

curl_setopt_array($ch, array(
    CURLOPT_POST => TRUE,
    CURLOPT_RETURNTRANSFER => TRUE,
    CURLOPT_HTTPHEADER => array(
        'Authorization: Bearer ' . $client->getAccessToken()['access_token'],
        'Content-Type: application/json'
    ),
    CURLOPT_POSTFIELDS => json_encode(array(
        'topicName' => 'projects/xxxx/topics/xxxx',
        'labelIds' => ["INBOX"]
    ))
));

Response:

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "forbidden",
    "message": "Error sending test message to Cloud PubSub projects/xxxx/topics/xxxx : User not authorized to perform this action."
   }
  ],
  "code": 403,
  "message": "Error sending test message to Cloud PubSub projects/xxxx/topics/xxxx : User not authorized to perform this action."
 }
}

More details:

• The scope used is GMAIL_READONLY.
• The suscription and the topic exist and they were created in the same console.
• I tried to publish a new message from the console and it has worked.

Answer 1

From the page: https://developers.google.com/gmail/api/guides/push#grant_publish_rights_on_your_topic

Cloud Pub/Sub requires that you grant Gmail privileges to publish notifications to your topic.

To do this, you need to grant publish privileges to serviceAccount:[email protected]. You can do this using the Cloud Pub/Sub Developer Console permissions interface following the resource-level access control instructions.

(emphasis added)

Answer 2

You have to grant permission to topics. Go to your topics list Or click on the below link https://console.cloud.google.com/cloudpubsub/topic.

Then click on your topic

Then in right side permission tab, click on the ADD MEMBER button

Then enter the new member email or If your App have multiple user then you can enter allUsers. Then Select the role Pub/Sub Publisher and click on the Save button.
Note: This will make your topic public.