I got stuck on the same problem of this post and couldn't make it work.
When I try to edit kube-proxy using kubeadm and the config file as hinted, I get the following error:
sudo kubeadm init --config ~/kube-proxy-custom.yaml
I0709 17:02:12.954172 67469 initconfiguration.go:207] loading configuration from "/home/andrea/kube-proxy-custom_old.yaml"
W0709 17:02:12.954627 67469 strict.go:54] error unmarshaling configuration schema.GroupVersionKind{Group:"kubeproxy.config.k8s.io", Version:"v1alpha1", Kind:"KubePro
while decoding JSON: json: cannot unmarshal string into Go struct field KubeProxyConfiguration.featureGates of type map[string]bool
v1alpha1.KubeProxyConfiguration.FeatureGates: ReadMapCB: expect { or n, but found ", error found in #10 byte of ...|reGates":"ServiceTop|..., bigger context ...|kubepr
"ServiceTopology=true","kind":"KubeProxyConfigurati|...
With kube-proxy-custom.yaml as:
apiVersion: kubeproxy.config.k8s.io/v1alpha1
kind: KubeProxyConfiguration
featureGates: "ServiceTopology=true"
I don't know if it's a go problem or if I'm doing anything wrong. I've tried with both k8s 1.17 and 1.18.5, go 1.13.5 and 1.14.4. Thank you for any feedback