CVS/GCP: Trident fails for shared VPCs

[okrause]

Describe the bug
Creating a PVC fails when using a shared-VPC on GCP. Please see details below.

Environment
Create two projects in GCP. Make one project into a host project by sharing its VPC to the other project (which becomes a service project). See https://cloud.google.com/vpc/docs/provisioning-shared-vpc

• Trident version: 21.01.0
• Trident installation flags used: standrad
• Container runtime: [e.g. Docker 19.03.1-CE]
• Kubernetes version: recent GKE
• Kubernetes orchestrator: GKE
• Kubernetes enabled feature gates: -
• OS: Ubuntu
• NetApp backend types: CVS for GCP
• Other:

Root cause analysis and problem resolution
CVS API expect the service project number. This is build in gcp/api/gcp.go in makeURL:

func (d *Client) makeURL(resourcePath string) string {
	return fmt.Sprintf("%s/v2/projects/%s/locations/%s%s", d.config.APIURL, d.config.ProjectNumber,
		d.config.APIRegion, resourcePath)
}

The same project number is used to craft the network parameter:

trident/storage_drivers/gcp/gcp_cvs.go

Line 719 in b0d5734

gcpNetwork := fmt.Sprintf("projects/%s/global/networks/%s", d.Config.ProjectNumber, network)

gcpNetwork := fmt.Sprintf("projects/%s/global/networks/%s", d.Config.ProjectNumber, network)

This works fine in the standalone project case. For shared-VPCs, the network sting needs to include the host project number, not the service project number.

This is how this was solved for the CVS/GCP Terraform provider: https://github.com/NetApp/terraform-provider-netapp-gcp/blob/28a6f92d1eb5a2250a1398966bd6ed5eaf9a6be0/gcp/volume.go#L314

	var projectID string
	if request.SharedVpcProjectNumber != "" {
		projectID = request.SharedVpcProjectNumber
	} else {
		projectID = c.GetProjectID()
	}
	request.Network = fmt.Sprintf("projects/%s/global/networks/%s", projectID, request.Network)

[balaramesh]

This has been fixed with e4b47c and will be available with Trident v21.04