cloud-functions v2 - fix reference to bucket_name

[wiktorn]

Use local variable for storage source as it is done for v1 functions.

When bucket_name is provided on input of the module then creation of v2 function fails with an error:

╷
│ Error: Invalid index
│ 
│   on .terraform/modules/[...]/modules/cloud-function/main.tf line 144, in resource "google_cloudfunctions2_function" "function":
│  144:         bucket = google_storage_bucket.bucket[0].name
│     ├────────────────
│     │ google_storage_bucket.bucket is empty tuple
│ 
│ The given key does not identify an element in this collection value: the collection has no elements.

These changes fixes this error.

Copied tests from v1 functions to ensure that v2 function is working properly.

[wiktorn]

One more thing I noticed with Cloud Functions v2 is that they do not support eventarc triggers.

Because of the difference in structure I think that the best approach is to create separate variable that contains necessary variables. If you are OK with this approach, I can work on that in separate PR.

[ludoo]

One more thing I noticed with Cloud Functions v2 is that they do not support eventarc triggers.

Because of the difference in structure I think that the best approach is to create separate variable that contains necessary variables. If you are OK with this approach, I can work on that in separate PR.

Sure. It would be great to also refactor the cloud function module to leverage Terraform 1.3 optional, like we've been doing for several other modules. Would you be up for it?

[wiktorn]

@ludoo sure, I'll come back with another PR soon.