1. The problem

Debugging push notification issues requires skill and effort. It's very helpful to be able to send targeted push notification to designated device for testing purposes.

In this blog, I will document how to achieve it.

A heads-up, the main hurdle lies in retrieveing an access token for authentication. Compared to the legacy API that used a server key, the new one requires a bit of extra work to get the API to function properly (for good reason).

2. The solution

Endpoint:

POST https://fcm.googleapis.com/v1/projects/{YOUR-PROJECT-ID}/messages:send

Get {YOUR-PROJECT-ID} from Firebase console, Project Settings > General

Body:

{
   "message":{
      "token": "FCM token on device",
      "notification":{
        "body":"This is an FCM notification message!",
        "title":"FCM Message"
      }
   }
}

Headers:

Content-Type: application/json

Authorization: Bearer {accessToken}

To retrieve accessToken, you need:

1. gcloud CLI

2. Private key file in JSON format (From Project Settings > Service Accounts.)

Using GOOGLE_APPLICATION_CREDENTIALS environment variable:

GOOGLE_APPLICATION_CREDENTIALS=/path/to/your/secret.json /path/to/your/google-cloud-sdk/bin/gcloud auth application-default print-access-token

An access token will be printed to the terminal. Use it for the Authorization header.

Thank you for reading! Cheers!