Disable Kubernetes ClusterIP service environment variables on pods - kubernetes

Question

Whenever a new pod is created in the cluster, environment variables related to the default Kubernetes clusterIP service are being injected into it.
Kubernetes clusterIp service running:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.116.0.1 <none> 443/TCP 27d
No matter on which namespace the pod is running, the following env vars will always appear:
KUBERNETES_SERVICE_PORT=443
KUBERNETES_PORT=tcp://10.116.0.1:443
KUBERNETES_PORT_443_TCP_ADDR=10.116.0.1
KUBERNETES_PORT_443_TCP_PORT=443
KUBERNETES_PORT_443_TCP_PROTO=tcp
KUBERNETES_SERVICE_PORT_HTTPS=443
KUBERNETES_PORT_443_TCP=tcp://10.116.0.1:443
KUBERNETES_SERVICE_HOST=10.116.0.1
I'm using enableServiceLinks=false as a mechanism to avoid service environment variables to be injected into pods, but it looks like it doesn't work for the default Kubernetes clusterIp service.
Deployment manifest:
apiVersion: apps/v1
kind: Deployment
metadata:
name: indecision-app-deployment
labels:
app: indecision-app
spec:
selector:
matchLabels:
app: indecision-app
template:
metadata:
labels:
app: indecision-app
spec:
enableServiceLinks: false
containers:
- name: indecision-app
image: hleal18/indecision-app:latest
ports:
- containerPort: 8080
Is it expected that enableServiceLinks=false also avoids the default Kubernetes clusterIP service of being injected?

Answer 1

In k8s source code you can find this comment:
// We always want to add environment variabled for master services
// from the master service namespace, even if enableServiceLinks is false.
and the code that adds these environemt variables:
if service.Namespace == kl.masterServiceNamespace && masterServices.Has(serviceName) {
if _, exists := serviceMap[serviceName]; !exists {
serviceMap[serviceName] = service
}
As you can see, kubelet adds services from masterServiceNamespace which defaults to "default".
Digging a bit more I have found out that there is a flag --master-service-namespace
--master-service-namespace The namespace from which the kubernetes master services should be injected into pods (default "default") (DEPRECATED: This flag will be removed in a future version.)
Now the flag is depricated and may be deleted in future.
Setting it on every kubelet should solve your issue but this is probably not the best thing to do as it is probably depricated for a reason.