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Installing Virtlet on a real cluster

For Virtlet to work, the following prerequisites have to be fulfilled on the nodes which will run them:

  1. Node names must be resolvable via DNS configured on the nodes
  2. AppArmor and SELinux must be disabled on the nodes

Virtlet deployment consists of preparing the nodes and then deploying the Virtlet DaemonSet.

Installing CRI Proxy

Virtlet requires CRI Proxy package to be able to run as DaemonSet on the nodes and support runnings system pods like kube-proxy there. To install CRI Proxy, please follow the steps from its documentation. Repeat it on each node that's going to run Virtlet.

Deploying Virtlet DaemonSet

First, you need to apply extraRuntime=virtlet label to each node that will run Virtlet DaemonSet (replace XXXXXX with the node name):

kubectl label node XXXXXX extraRuntime=virtlet

Then you need to install image translations configmap. You can use the default one:

curl https://raw.githubusercontent.com/Mirantis/virtlet/master/deploy/images.yaml >images.yaml
kubectl create configmap -n kube-system virtlet-image-translations --from-file images.yaml

Then you can deploy Virtlet DaemonSet:

kubectl apply -f https://raw.githubusercontent.com/Mirantis/virtlet/master/deploy/virtlet-ds.yaml

By default it has KVM enabled, but you can configure Virtlet to disable it. In order to do so, create a configmap named virtlet-config in kube-system prior to creating Virtlet DaemonSet that contains key-value pair disable_kvm=y:

kubectl create configmap -n kube-system virtlet-config --from-literal=disable_kvm=y

After completing this step, you can look at the list of pods to see when Virtlet DaemonSet is ready:

kubectl get pods --all-namespaces -o wide -w

Testing the installation

To test your Virtlet installation, start a sample VM:

kubectl create -f https://raw.githubusercontent.com/Mirantis/virtlet/master/examples/cirros-vm.yaml
kubectl get pods --all-namespaces -o wide -w

And then connect to console:

$ kubectl attach -it cirros-vm
If you don't see a command prompt, try pressing enter.

Press enter and you will see:

login as 'cirros' user. default password: 'cubswin:)'. use 'sudo' for root.
cirros-vm login: cirros
Password:
$

Escape character is ^]

You can also ssh into the VM. There's a scripts vmssh.sh that you can use to access the VM. You can download it from Virtlet repository along with test ssh key:

wget https://raw.githubusercontent.com/Mirantis/virtlet/master/examples/{vmssh.sh,vmkey}
chmod +x vmssh.sh
chmod 600 vmkey

vmssh.sh needs kubectl to be configured to access your cluster.

./vmssh.sh cirros@cirros-vm

Removing Virtlet

In order to remove Virtlet, first you need to delete all the VM pods.

You can remove Virtlet DaemonSet with the following command:

kubectl delete daemonset -R -n kube-system virtlet

After doing this, remove CRI proxy from each node by reverting the changes in Kubelet flags, e.g. by removing /etc/systemd/system/kubelet.service.d/20-virtlet.conf in case of kubeadm scenario described above. After this you need to restart kubelet and remove the CRI Proxy binary (/usr/local/bin/criproxy) and its node configuration file (/etc/criproxy/node.conf).