pod networking : flannel

aravipati

Hi [Sebastian],

Since the exam is using Ubuntu Xenial (16.04) and Kubernetes v1.6.2, I am trying to create a cluster using these versions. And I am trying to do this in Vagrant so that I can test locally.

My topology has one master and one worker. I also ensured that both the nodes have Docker 1.12.6~cs13-0~ubuntu-xenial.

[On the master] I created the cluster using the following command:

  kubeadm init --pod-network-cidr=10.244.0.0/16 --kubernetes-version=v1.6.2 --apiserver-advertise-address=10.0.0.10

I edited kube-flannel.yml to add "--iface=eth1" and then did 

  kubectl apply -f kube-flannel.yml

I can see that a new pod is created for flannel and it is "Running". However the dns pod is stuck in "Pending".

The master node is also stuck in "NotReady".

I checked the logs for the flannel pod and it has no errors. I also ensured that a flannel configuration file exists in "/etc/cni/net.d/10-flannel.conflist".

I also connected to the etcd pod and did a query as I expect flannel to insert a KV. But etcdctl returned no results.

[On the worker] I joined the worker node to the cluster and can see that a new flannel pod is created. However the worker is also stuck in "NotReady". I can see that the worker node has the flannel configuration file in "/etc/cni/net.d/10-flannel.conflist".

The cluster goes to "Ready" if I use the Weave plugin

  kubectl apply -f https://git.io/weave-kube-1.6

Is there a flannel manifest that is specific to Kubernetes 1.6.2?

Thanks.

serewicz

There was an update to flannel which required access to portmap, but this was not included in any documentation. If you load 

wget https://github.com/projectcalico/cni-plugin/releases/download/v1.9.1/portmap

Move the binary to the expected directory and change the access mode.

sudo mv portmap /opt/cni/bin/portmap

sudo chmod 755 /opt/cni/bin/portmap


Find the current kube-dns container that is not in a
Running state.

kubectl get pods --all-namespaces
    ....
    kube-system kube-dns-545bc4bfd4-xtwn7 0/3 ContainerCreating 0 26m
    ....

Delete the container. It should spawn a new container which
will show a Running state quickly. Your container names
will be different.

kubectl delete pod kube-dns-545bc4bfd4-xtwn7 -n kube-system

kubectl get pods --all-namespaces

Regards,

fcioanca

Hi,

The CKA exam was updated to Kubernetes 1.9.1 this morning.

Thank you,

Flavia