google_storage_bucket_object is missing a generation output

[mattmoor]

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Terraform Version

Terraform v1.3.8
on darwin_arm64
+ provider registry.terraform.io/hashicorp/google v4.58.0
+ provider registry.terraform.io/hashicorp/random v3.4.3

Affected Resource(s)

• google_storage_bucket_object

Terraform Configuration Files

resource "random_id" "id" {
  byte_length = 4
}

resource "google_storage_bucket" "example-bucket" {
  name          = "mattmoor-example-${random_id.id.hex}"
  location      = "US"
  force_destroy = true

  uniform_bucket_level_access = true
}

resource "google_storage_bucket_object" "example-object" {
  name   = "example-object"
  bucket = google_storage_bucket.example-bucket.name
  content = <<EOF
    This is the object content I want to appear in GCS
  EOF
}

Debug Output

N/A

Panic Output

N/A

Expected Behavior

I would expect google_storage_bucket_object to have a .generation attribute.

Downstream resources referencing this object via:

gs://${google_storage_bucket.example-bucket.name}/${google_storage_bucket_object.example-object.name}

... will have a bad time because the reference doesn't reflect potential content changes in the object made by IaC.

🚨 This is why I am filing this as a bug, not a feature. 🚨

An example of such a resource: https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/dataflow_job

Generally downstream resources should reference a form like this, which incorporates the generation and is immutable:

gs://my-awesome-bucket/just-a-folder/cloud-storage.logo.png#1456530077282000

Actual Behavior

The only place the generation appears to be surfaced at all is embedded in media_link, e.g.

media-link = "https://storage.googleapis.com/download/storage/v1/b/mattmoor-example-9ade25ca/o/example-object?generation=1680001044297616&alt=media"

Steps to Reproduce

Try to access generation

Important Factoids

Mutable references in declarative infrastructure are incredibly problematic. Generally you want to reference immutable identifiers which change exactly when the resource changes, so that changes cascade through the dependency graph.

Better than simple vendor-enforced immutability is content-addressability, but alas the former is the best we are likely to see from GCS.

Another great example of this is tags vs. digests in Kubernetes, which is my personal "hill to die on".

References

This feels related but different: #10488

b/276933153

[benwatsonnandos]

This would be really useful. Here's a regex to extract the generation in Terraform:

generation = tonumber(regex("generation=(\\d+)", google_storage_bucket_object.archive.media_link)[0])

[jc0b]

This would be reaaally nice to be able to do, especially in conjunction with google_cloudfunctions2_function, which takes the generation of an object as an argument if you're using GCS for your storage_source.

[jakewan]

@jc0b It's funny you mention this. This issue is exactly what provided the ummmph I needed to move to Cloud Build triggers to deploy Cloud Function changes.

[github-actions]

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