Description of problem:

User get sync error when changing network configuration on top of existing configuration

  - lastProbeTime: "2023-08-22T11:47:57Z"
    lastTransitionTime: "2023-08-22T11:47:57Z"
    message: 'The Spec could not be synced due to an input error: Dual-stack cluster
      cannot be created with empty Machine Networks'
    reason: InputError
    status: "False"
    type: SpecSynced

How reproducible:

Steps to Reproduce:

1. apply configuration with machine network cidr
2. change network configuration
3. getting the error

Actual results:

  - lastProbeTime: "2023-08-22T11:47:57Z"
    lastTransitionTime: "2023-08-22T11:47:57Z"
    message: 'The Spec could not be synced due to an input error: Dual-stack cluster
      cannot be created with empty Machine Networks'
    reason: InputError
    status: "False"
    type: SpecSynced

Expected results:

sync should work

Additional info:

Looks like the issue is that update function doesn't consider the existing values and expect a patch operation

https://github.com/openshift/assisted-service/blob/ba04805cce13bf9b32647539c33ee63f85831586/internal/cluster/validations/validations.go#L561

this issue is probably relevant to all the parameters, because the api is patch it means that it should take into account the existing values from the cluster

A workaround to this specific issue is to set a new valid value in the machine networks and then update it back into the old value.