I have this basic Dockerfile:

FROM nginx
RUN apt-get -y update && apt install -y curl

In the master node of my Kubernetes cluster I build that image:

docker build -t cnginx:v1 . 

docker images shows that the image has been correctly generated:

REPOSITORY                                 TAG                 IMAGE ID            CREATED             SIZE
cgninx                                     v1                  d3b1b19d069e        39 minutes ago      141MB

I use this deployment referencing this custom image:

apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2 
  template: 
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: cnginx
        image: cnginx:v1
        imagePullPolicy: Never
        ports:
        - containerPort: 80
      nodeSelector:
        nodetype: webserver

However the image is not found:

NAME                                READY     STATUS              RESTARTS   AGE
nginx-deployment-7dd98bd746-lw6tp   0/1       ErrImageNeverPull   0          4s
nginx-deployment-7dd98bd746-szr9n   0/1       ErrImageNeverPull   0          4s

Describe pod info:

Events:
  Type     Reason                 Age              From                Message
  ----     ------                 ----             ----                -------
  Normal   Scheduled              1m               default-scheduler   Successfully assigned nginx-deployment-7dd98bd746-szr9n to kubenode2
  Normal   SuccessfulMountVolume  1m               kubelet, kubenode2  MountVolume.SetUp succeeded for volume "default-token-bpbpl"
  Warning  ErrImageNeverPull      9s (x9 over 1m)  kubelet, kubenode2  Container image "cnginx:v1" is not present with pull policy of Never
  Warning  Failed                 9s (x9 over 1m)  kubelet, kubenode2  Error: ErrImageNeverPull

I have also tried using the default imagePullPolicy, and some other things such as tagging the image with latest...

So, how can I make Kubernetes use a locally generated docker image?