Best way to retrieve Google Cloud Run ID Token in n8n Cloud

Questions
1

I’m using n8n Cloud, so I cannot install custom libraries or modules.

I have a service running on Google Cloud Run that requires authentication. To access it, I need to generate a Google-signed ID token and include it in the Authorization: Bearer <token> header of my HTTP request.

Since n8n Cloud doesn’t support adding external libraries like google-auth-library, I’m struggling to find the best way to generate this ID token from within an n8n workflow.

So far, I’ve considered:

  • Creating a separate Google Cloud Function or Cloud Run service that returns an ID token when given a target_audience.
  • Trying to manually build a JWT and call the OAuth2 endpoint (but that’s not really feasible without crypto libraries).

Does anyone have a working setup for retrieving a Google-signed ID token in n8n Cloud or a good workaround you’d recommend?

Thanks in advance!

2

Hello @mknbusiness!

Honestly it is an interesting question and I have done some research to help you, you will have to tell me if it will really be like this :slightly_smiling_face:

  1. Create a lightweight Google Cloud Function (or Cloud Run service). Uses Application Default Credentials (ADC)

google.auth.default().fetchIdToken(targetAudience)

and returns the ID token as JSON

  1. From n8n, use an HTTP Request node to call this function with your target_audience.

  2. Use the returned ID token in another HTTP request to your private Cloud Run service:

Authorization: Bearer {{$json["id_token"]}}

3

I figured out how to do a very similar “JWT Client Adapter” thing (that doesn’t require extra libraries, so it should work on n8n cloud). Assuming you already have an HTTP based endpoint to “generate a Google-signed ID token” (JWT?), you might get some ideas about how to solve this interaction, and keep the credentials safe/hidden, from this post.