Add the possibility to check if a file exist in a bucket

[sylvainar]

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Description

Currently, if we're using data source google_storage_bucket_object on a file that does not exist, the terraform plan exits with a 404 error. Could it be possible that we let this call return a null value, or something we can exploit in order to conditionally do things in the plan?

For better understanding, here's my usecase: I have a cloud function on GCP, its code is send via gsutil on our CI/CD platform, but I still want to provision this cloud function with terraform. I'd like to check if the source code of this function is present in the bucket. If not, I'd like to be able to skip the creation of the cloud function.

New or Affected Resource(s)

• google_storage_bucket_object

Potential Terraform Configuration

data "google_storage_bucket_object" "cf_source" {
  name   = "${terraform.workspace}/src.zip"
  bucket = "cf_bucket"
}

resource "whatever" "example" {
    count = "${data.google_storage_bucket_object.cf_source != null ? 1 : 0}"
}

References

• Maybe this is a more global issue according to this never-ending thread: Data sources should allow empty results without failing terraform#16380
• b/275624331

[rileykarson]

What's being asked for here is the opposite of intended behaviour for datasources nowadays, see #12873. At the time of this issue getting filed the behaviour was undefined, and we weren't sure what was best. Since then, datasources implicitly returning nulls has proven to cause hard-to-diagnose issues for customers, and the behaviour of the GCS object resource is consistent with current practices.

Additionally, given the evolving stance of the Terraform Core team at HashiCorp in hashicorp/terraform#16380 (comment) (and in numerous updates since then!), I don't believe kind of conditional configuration is an intended use case.

[github-actions]

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