Explicit reference causes import cycle error

[donovanmuller]

What happened?

With one specific GCP resource (google_service_networking_peered_dns_domain ) configured with an explicit Network reference, running make reviewable results in an error as described in this https://github.com/upbound/official-providers/pull/518#discussion_r943598464. Note that the Network reference is not automatically added via Upjet either.

https://github.com/upbound/official-providers/blob/7ac76a2a7d155838a7cc479b6dd8352357b1d79c/provider-gcp/config/cloudplatform/config.go#L93-L101

Removing the explicit reference allows for successful generation.

How can we reproduce it?

• Checkout commit 93afafc9361dfdf96bd2aa91d20cd2bdc29bebf3
• make && cd provider-gcp && make reviewable

What environment did it happen in?

• Crossplane Version: v1.9.0-up.2
• Provider Name: provider-gcp
• Provider Version: development - see https://github.com/upbound/official-providers/pull/518

[donovanmuller]

Another example of this error can be found in the InstanceGroupNamedPort resource config https://github.com/upbound/official-providers/blob/cba2980241265105e38d027b79b7486a69abb31b/provider-gcp/config/compute/config.go#L408-L415 In this example, the only way to get a reference to the InstanceGroup for the group field https://github.com/upbound/official-providers/blob/cba2980241265105e38d027b79b7486a69abb31b/provider-gcp/examples/compute/instancegroupnamedport.yaml#L11-L14 is to get it via the GKE Cluster's implicitly created nodePool attribute https://github.com/upbound/official-providers/blob/cba2980241265105e38d027b79b7486a69abb31b/provider-gcp/config/compute/config.go#L445-L459

However, adding the v1beta1.Cluster reference type in config/compute/config.go results in an import cycle.

[muvaf]

This is a general problem regarding references that we need to fix in upstream crossplane/crossplane-runtime#313 Though we may implement a proprietary reference resolver in Upjet to handle these cases.

[luebken]

Severity:low as we currently don't encounter this often. Please add your use-case if you encounter this.

[haarchri]

we have this case also for an zscaler provider

(⎈|kind-sop-local:N/A)➜  crossplane-provider-zpa git:(master) ✗ make run
19:34:31 [ .. ] go build linux_arm64
package github.com/xx/crossplane-provider-zpa/cmd/provider
        imports github.com/xx/crossplane-provider-zpa/apis
        imports github.com/xx/crossplane-provider-zpa/apis/zpaapplicationsegment/v1alpha1
        imports github.com/xx/crossplane-provider-zpa/apis/zpaservergroup/v1alpha1
        imports github.com/xx/crossplane-provider-zpa/apis/zpaapplicationserver/v1alpha1
        imports github.com/xx/crossplane-provider-zpa/apis/zpaservergroup/v1alpha1: import cycle not allowed
19:34:31 [FAIL]
make: *** [go.build] Error 1