For GCP a Service Account access key within the project is required. This most easily done as JSON file which can be uploaded to Scalr.

  • In the Google console navigate to API & Services -> Credentials.

  • Click on a Service Account or create one.

  • Add a key.

  • Choose JSON and Create.

resource "scalr_provider_configuration" "google" {
 name       = "google_main"
  account_id = "acc-xxxxxxxxx"
  google {
    project     = "my-project"
    credentials = "my-credentials"

The above is an example, please see the full provider documentation here.