compute: unable to resize instance group to 0

[matihost]

https://github.com/googleapis/google-cloud-go/blob/main/compute/apiv1/instance_group_managers_client.go#L1301

When size is 0, the size parameter is not added to HTTP param - and server returns 400 bad request - leading to unability to resize intance group to 0.

The gcloud cli works:

gcloud compute instance-groups managed resize NAME  --zone=ZONE --size=0

[codyoss]

cc @noahdietz WDYT? A bug perhaps?

[noahdietz]

Yep, this is a bug. There are only 3 int32 fields in compute that are marked as REQUIRED (and thus not optional->*int32), and I believe the intention of this code was to prevent sending unset fields (default empty) in the request. In the event that a number field is REQUIRED, 0 is a valid value and we must send it.

This does potentially open up users to some confusing errors/scenarios if they don't set the field (because there isn't a good way to enforce required fields in Go unless they are pointers) and the default empty 0 is sent.

We probably want to include some extra documentation to the method to ensure it is explicitly set by the user. I will open an issue on the generator to fix this and we can close this one when it is regenerated. Extra documentation might come in a separate issue/PR as that might benefit non-diregapic clients as well.

[noahdietz]

Opened googleapis/gapic-generator-go#819 to track the bug fix.

[noahdietz]

https://pkg.go.dev/cloud.google.com/[email protected] should have the fix

google-cloud-go/compute/apiv1/instance_group_managers_client.go

Lines 1297 to 1302 in 5563382

	params := url.Values{}
	if req != nil && req.RequestId != nil {
	params.Add("requestId", fmt.Sprintf("%v", req.GetRequestId()))
	}
	params.Add("size", fmt.Sprintf("%v", req.GetSize()))