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Direct Resource External Reference Guide

TL;DR

status.externalRef should be used as the GCP identifier of the Config Connector resource.

Basic Rules

  • Config Connector should assign the status.externalRef value when it initially acquires or creates the GCP resource.

  • Config Connector should use status.externalRef as the GCP identifier to retrieve, update and delete (if applicable) the resource.

  • Config Connector should validate the spec corresponding identifiers (i.e. spec.projectRef spec.location, spec.resourceID) based on status.externalRef.

  • The status.externalRef value can be used as the resource reference <kind>Ref.External

  • Config Connector shall not write the Direct resources' resource ID back to the spec.resourceID field. Only users should configure the spec fields.1

reconcile diagram

API definition

type <Kind>Status struct {
   /* A unique specifier for the <Kind> workerpool resource in GCP.*/
   ExternalRef *string json:"externalRef,omitempty"
   ...
}

status.externalRef format

The status.externalRef shall use the cloud asset inventory as reference to build its value. The service domain can be omitted.

  • If a resource has multiple asset inventory, we choose the newer one in the resource name format list (normally the bottom ones).
  • If a resource is not supported in the asset inventory, we shall refer to the resources’ REST API references to use the resource path.

Enhancement to the service-generated ID resource

  • If a resource does not let user to specify the name or identifier, but its GCP service assigns an ID in the HTTP response, the Direct reconciler will use the service generated ID to build the status.externalRef, but not write back to the spec.resourceID.

  • If user specifies the service-generated ID in the spec.resourceID field, the Direct reconciler will acquire the resource if the status.externalRef is not assigned.

Backward compatibility for TF/DCL based reconcilers

The existing TF-based and DCL-based reconciliation treats the spec.resourceID as the single Source of Truth to identify a GCP resource. It writes back the spec.resourceID after reconciliation. Here are the known problems. Config Connector will keep the bahavior of these resources, until they are migrated to the Direct reconciler.

Footnotes

  1. Existing Terraform-based or DCL-based resources still have Config Connector written back to the spec.resourceID field for backward compatibility reasons. ↩