How to Import an Google Spanner Database IAM Binding into Terraform

Import Google Spanner Database IAM Binding with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Google Cloud Spanner resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live Google Spanner Database IAM Binding to managed Terraform.

terraback scan all gcp --project my-gcp-project

terraback gcp import --method bulk

The Terraform import block

Terraback emits a Terraform 1.5+ import block like the one below. Because the block lives in your configuration, the import is reviewable in a pull request and repeatable across environments.

import {
  to = google_spanner_database_iam_binding.readers
  id = "my-project/my-instance/my-database roles/spanner.databaseReader"
}

Example google_spanner_database_iam_binding configuration

Here is a realistic Google Spanner Database IAM Binding block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "google_spanner_database_iam_binding" "readers" {
  instance = google_spanner_instance.main.name
  database = google_spanner_database.main.name
  role     = "roles/spanner.databaseReader"
  members  = [
    "user:jane@example.com",
    "serviceAccount:app@my-project.iam.gserviceaccount.com",
  ]
}

Gotchas when importing a Google Spanner Database IAM Binding

• An iam_binding is authoritative for the role on that database: it overwrites the full member list, so any member omitted from members loses access.
• Use google_spanner_database_iam_member for additive grants when you do not want to own the entire role.
• The import ID uses slash-separated project/instance/database, then a space, then the role; this differs from the project IAM format.
• The binding targets one database; granting at the instance level instead requires google_spanner_instance_iam_binding.

Doing it manually with terraform import

The native approach is to write the google_spanner_database_iam_binding block by hand, then run terraform import google_spanner_database_iam_binding.example <import-id> for every resource, one at a time. That works for a handful of resources, but it does not scale: you author all the HCL yourself and repeat the command for each item. Terraback generates the HCL and the import blocks for your whole account in one pass.

Import other Google Cloud resources