containerd and crio should default to --network-plugin-cni --enable-default-cni

[tstromberg]

With v0.33.1 and:

minikube start --vm-driver=kvm2 --container-runtime=containerd with or without --network-plugin-cni,
CoreDNS is stuck in pending:

$ kubectl get pods --all-namespaces
NAMESPACE     NAME                                   READY     STATUS              RESTARTS   AGE
default       foo-56c8f67c67-58gfk                   0/1       Pending             0          6m
kube-system   coredns-86c58d9df4-2nh9j               0/1       ContainerCreating   0          6m
kube-system   coredns-86c58d9df4-k847v               0/1       ContainerCreating   0          6m
kube-system   etcd-minikube                          1/1       Running             0          5m
kube-system   kube-addon-manager-minikube            1/1       Running             0          5m
kube-system   kube-apiserver-minikube                1/1       Running             0          5m
kube-system   kube-controller-manager-minikube       1/1       Running             0          5m
kube-system   kube-proxy-t5nlj                       1/1       Running             0          6m
kube-system   kube-scheduler-minikube                1/1       Running             0          5m
kube-system   kubernetes-dashboard-ccc79bfc9-679n5   0/1       Pending             0          2m
kube-system   storage-provisioner                    0/1       Pending             0          6m

$ kubectl describe pod coredns-86c58d9df4-k847v -n kube-system
Name:               coredns-86c58d9df4-k847v
Namespace:          kube-system
Priority:           0
PriorityClassName:  <none>
Node:               minikube/192.168.122.227
Start Time:         Tue, 22 Jan 2019 10:33:51 -0800
Labels:             k8s-app=kube-dns
                    pod-template-hash=86c58d9df4
Annotations:        <none>
Status:             Pending
IP:                 
Controlled By:      ReplicaSet/coredns-86c58d9df4
Containers:
  coredns:
    Container ID:  
    Image:         k8s.gcr.io/coredns:1.2.6
    Image ID:      
    Ports:         53/UDP, 53/TCP, 9153/TCP
    Host Ports:    0/UDP, 0/TCP, 0/TCP
    Args:
      -conf
      /etc/coredns/Corefile
    State:          Waiting
      Reason:       ContainerCreating
    Ready:          False
    Restart Count:  0
    Limits:
      memory:  170Mi
    Requests:
      cpu:        100m
      memory:     70Mi
    Liveness:     http-get http://:8080/health delay=60s timeout=5s period=10s #success=1 #failure=5
    Environment:  <none>
    Mounts:
      /etc/coredns from config-volume (ro)
      /var/run/secrets/kubernetes.io/serviceaccount from coredns-token-rgjp8 (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             False 
  ContainersReady   False 
  PodScheduled      True 
Volumes:
  config-volume:
    Type:      ConfigMap (a volume populated by a ConfigMap)
    Name:      coredns
    Optional:  false
  coredns-token-rgjp8:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  coredns-token-rgjp8
    Optional:    false
QoS Class:       Burstable
Node-Selectors:  <none>
Tolerations:     CriticalAddonsOnly
                 node-role.kubernetes.io/master:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type     Reason           Age                From               Message
  ----     ------           ----               ----               -------
  Normal   Scheduled        6m                 default-scheduler  Successfully assigned kube-system/coredns-86c58d9df4-k847v to minikube
  Warning  NetworkNotReady  1m (x152 over 6m)  kubelet, minikube  network is not ready: [runtime network not ready: NetworkReady=false reason:NetworkPluginNotReady message:Network plugin returns error: cni plugin not initialized]

This works perfectly:

minikube start --vm-driver=kvm2 --container-runtime=containerd --network-plugin=cni --enable-default-cni

If --container-runtime=containerd is specified, we should default to good defaults to improve the user experience.

[afbjorklund]

Probably we can put the socket overrides in slightly smaller print, as well ? (the "extended version")
With the latest kubernetes checks, stating the CRI being used is now mandatory anyway...

https://github.com/kubernetes/minikube/blob/master/docs/alternative_runtimes.md

    --cri-socket=/var/run/crio/crio.sock \
    --extra-config=kubelet.container-runtime=remote \
    --extra-config=kubelet.container-runtime-endpoint=unix:///var/run/crio/crio.sock \
    --extra-config=kubelet.image-service-endpoint=unix:///var/run/crio/crio.sock

Same story there, the defaults are good enough.

[afbjorklund]

@tstromberg : this feature would be nice to have in 1.0