nilref panic when configuring leader election

[tomasaschan]

The Kubebuilder Book includes a tutorial on setting up a manager to use a custom config file, e.g. volume-mounted from a config map. As part of this tutorial, it is suggested to run

options := ctrl.Options{Scheme: scheme}
options, err := options.AndFrom(ctrl.ConfigFile().AtPath(configPath).OfKind(&MyCustomConfigType{}))
// ...

where MyCustomConfigType is defined something like this:

import (
    metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    cfg "sigs.k8s.io/controller-runtime/pkg/config/v1alpha1"
)

type MyCustomConfigType struct {
    metav1.TypeMeta `json:",inline"`

    cfg.ControllerManagerConfigurationSpec `json:",inline"`
    
    // add custom config props here
}

If the config file does not provide any configuration for leader election (which should be OK, since the element is optional in the config type), you'll get a nilref panic in setLeaderElectionConfig, since obj.LeaderElection == nil.