Replacing ClusterIP service with NodePort service fails

[wombat]

It had a service with type ClusterIP and wanted to switch it to type NodePortand it failed with the following message:
`The Service "xyz" is invalid.
spec.clusterIP: Invalid value: "": field is immutable``

I deleted the existing service and created the new one which worked fine.

[bprashanth]

How did you change it? sounds like you tried to apply an update with clusterIP=="" whereas the Service in the apiserver already had a clusterIP.

Fyi the easiest way to update a Service is simply to run kubectl edit svcName, and change the one field (in this case Type from ClusterIP to NodePort).

[wombat]

I just did a kubectl replace .... Using ´kubectl edit` from a CI is not possible so I just wanted to replace the service completely.
At first it looked like this:

apiVersion: v1
kind: Service
metadata:
  name: webapp
spec:
  ports:
    - port: 80
      targetPort: 80
  selector:
    name: webapp

afterwards:

apiVersion: v1
kind: Service
metadata:
  name: webapp
spec:
  type: NodePort
  ports:
    - port: 80
      targetPort: 80
  selector:
    name: webapp

[bprashanth]

A simple replace will try to update (get and re-put) which will try to preserve the clusterIP. A replace --force will delete and create. Does that work?

[wombat]

I can try later but I don´t understand why switching to NodePort leads to an error - I haven´t deleted the ip or similar.

[bprashanth]

Without debugging too deep I believe it's because kubectl replace will do a GET followed by a PUT. The put therefore has the ClusterIP set to some non "" value (the same value it's currently set to in etcd). This causes an update violation.

You can confirm by running kubectl replace blah --v=7 and observing the REST calls.

One might argue that this behavior is unexpected, or that we should allow the same value to pass through etc, @kubernetes/kubectl

[sheerun]

Maybe you could implement "destroy-handlers" for some keys. e.g. handler that runs when ClusterIP is changed to some other property and sets clusterIP to default value.

[thockin]

replace is a full replacement, not a patch. It is invalid to change ClusterIP, and in this case you are changing it from a value to "". To replace a Service you really have to do an R-M-W cycle. Get it, apply mutations, then write it back.