Invalid Argument error when calling signJWT

Question

I am following this documentation https://cloud.google.com/iam/docs/reference/credentials/rest/v1/projects.serviceAccounts/signJwt to generate a signed JWT

Path Parameter: name: projects/-/serviceAccounts/test-acc@123.iam.gserviceaccount.com

This is my request body

{
  "delegates": []
  "payload": "{'sub': 'test-acc@123.iam.gserviceaccount.com', 'iat': 1661250118, 'exp': 1661253718, 'aud': 'https://www.googleapis.com/auth/iam'}"
}

I am getting this invalid argument error.

Am I missing something in the payload?

I dont think I have any issues with permission as I was able to get success response when I tried generateAccessToken api call

Answer 1

This worked for me by replacing all single quotes ( ' ) with \" (escaping double quotes)

{ "delegates": [], "payload": "{"sub": "test-acc@123.iam.gserviceaccount.com", "iat": 1661250118, "exp": 1661253718, "aud": "https://www.googleapis.com/auth/iam"}" }

Answer 2

You are missing a comma after "delegates": [], in the request body. It should follow the structure:

{
  "delegates": [
    string
  ],
  "payload": string
}