Support use of Private Service Connect endpoint in GKE google_container_cluster resource

[ncapps]

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Description

Creating a VPC network peering connection between the cluster VPC and the control plane VPC is not allowed in some enterprise uses cases. An alternative solution is connect the cluster VPC and control plane VPC using a Private Service Connect (PSC) endpoint.

The Terraform resource, google_container_cluster, should allow creating a private cluster without specifying the master_ipv4_cidr_block. This use case is supported with the gcloud container clusters create command.

gcloud container clusters create private-cluster \
    --enable-master-authorized-networks \
    --enable-ip-alias \
    --enable-private-nodes \
    --enable-private-endpoint \
    --network="shared-vpc" \
    --subnetwork="shared-vpc-subnet" \
    --private-endpoint-subnetwork="shared-vpc-subnet-nodes"

Using Terraraform, we currently cannot create a private cluster without providing a value for master_ipv4_cidr_block.

This configuration results in a Terraform build phase error.

private_cluster_config {
    enable_private_endpoint     = true
    enable_private_nodes        = true
    private_endpoint_subnetwork = "projects/project-id/regions/region/subnetworks/shared-vpc-subnet-nodes"
}

Error message:

module.kubernetes-engine.google_container_cluster.cluster: Creating...
╷
│ Error: master_ipv4_cidr_block must be set if enable_private_nodes is true

New or Affected Resource(s)

• google_container_cluster

Potential Terraform Configuration

• Add support for creating a private cluster (standard) that utilizes Private Service Connect endpoints to connect the cluster VPC with the control plane VPC.

resource "google_container_cluster" "cluster" {
...
    private_cluster_config {
        enable_private_endpoint     = true
        enable_private_nodes        = true
        private_endpoint_subnetwork = "projects/project-id/regions/region/subnetworks/shared-vpc-subnet-nodes"
    }
}

References

• b/290344299

[ncapps]

I will work on a fix for this issue.

[sanmaym]

@ncapps @rileykarson Can I get some clarification on this PR ? Are you trying to create a GKE cluster with private nodes which operates with PSC instead of VPC Peering? Is that possible today? My understanding was that its only supported for public GKE clusters and GKE cluster with private nodes was not supported yet

[ncapps]

Hi @sanmaym, Yes - we are creating GKE clusters with private nodes that use PSC. We have been using this configuration for over a year now. We needed to provision and manage the clusters using gcloud until this change was applied to the Google Terraform provider.

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