How to Import an Google Pub/Sub Subscription into Terraform

Import Google Pub/Sub Subscription with Terraback (recommended)

Terraback reverse-engineers your live infrastructure: it reads the Google Cloud Pub/Sub resource with read-only credentials, generates the HCL, and produces the exact import block. Two commands take you from a live Google Pub/Sub Subscription 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_pubsub_subscription.orders
  id = "projects/my-project/subscriptions/orders-sub"
}

Example google_pubsub_subscription configuration

Here is a realistic Google Pub/Sub Subscription block. Terraback generates a fuller version from your actual resource attributes; this is a minimal, valid starting point.

resource "google_pubsub_subscription" "orders" {
  name  = "orders-sub"
  topic = google_pubsub_topic.orders.id

  ack_deadline_seconds = 20
}

Gotchas when importing a Google Pub/Sub Subscription

• topic must be the full topic path (projects/{project}/topics/{name}); a bare topic name will not match the existing subscription and forces recreation.
• topic is immutable: a subscription cannot be moved to another topic, so any change destroys and recreates it.
• Push versus pull delivery is determined by whether a push_config block is present; importing a push subscription without that block plans an in-place change to pull.
• Dead-letter and retry policies reference other topics and are separate concerns; the dead-letter topic and its IAM are not imported with the subscription.

Doing it manually with terraform import

The native approach is to write the google_pubsub_subscription block by hand, then run terraform import google_pubsub_subscription.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