How to install Canonical Kubernetes in LXD¶
Canonical Kubernetes can also be installed inside an LXD virtual machine. This is a great way, for example, to test out clustered Canonical Kubernetes without the need for multiple physical hosts.
Why an LXD virtual machine and not a container? LXD privileged containers are no longer supported and some Kubernetes services, such as the Cilium CNI, cannot run inside unprivileged containers. Furthermore, by using virtual machine we ensure that the Kubernetes environment is well isolated.
Install LXD¶
Install LXD via snaps:
sudo snap install lxd
sudo lxd init
Start an LXD VM for Canonical Kubernetes¶
Create the VM that Canonical Kubernetes will run in.
lxc launch ubuntu:22.04 k8s-vm --vm -c limits.cpu=2 -c limits.memory=4GB
Install Canonical Kubernetes in an LXD VM¶
Install Canonical Kubernetes within the VM.
lxc exec k8s -- sudo snap install k8s --classic --channel=1.32-classic/stable
Note
Substitute your desired channel in the above command. Find the
available channels with snap info k8s and see the channels
explanation page for more details on channels, tracks and versions.
Access Canonical Kubernetes services within LXD¶
Assuming you accepted the default bridged networking when you initially setup LXD, there is minimal effort required to access Canonical Kubernetes services inside the LXD VM.
Simply note the interface IP address from the command:
lxc list k8s-vm
+--------+---------+------------------------+------------------------------------------------+-----------------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+--------+---------+------------------------+------------------------------------------------+-----------------+-----------+
| k8s-vm | RUNNING | 10.122.174.30 (enp5s0) | fd42:80c6:c3e:445a:216:3eff:fe8d:add9 (enp5s0) | VIRTUAL-MACHINE | 0 |
+--------+---------+------------------------+------------------------------------------------+-----------------+-----------+
and use this to access services running inside the VM.
Expose services to the VM¶
You’ll need to expose the deployment or service to the VM itself before
you can access it via the LXD VM’s IP address. This can be done using
k8s kubectl expose. This example will expose the deployment’s port 80 to a
port assigned by Kubernetes.
We will use Microbot as it provides a simple HTTP endpoint to expose. These steps can be applied to any other deployment.
First, initialise the k8s cluster with
lxc exec k8s-vm -- sudo k8s bootstrap
Now, let’s deploy Microbot (please note this image only works on x86_64).
lxc exec k8s-vm -- sudo k8s kubectl create deployment \
microbot --image=dontrebootme/microbot:v1
Then check that the deployment has come up.
lxc exec k8s-vm -- sudo k8s kubectl get all
…should return an output similar to:
NAME READY STATUS RESTARTS AGE
pod/microbot-6d97548556-hchb7 1/1 Running 0 21m
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.152.183.1 <none> 443/TCP 21m
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/microbot 1/1 1 1 21m
NAME DESIRED CURRENT READY AGE
replicaset.apps/microbot-6d97548556 1 1 1 21m
Now that Microbot is up and running, let’s make it accessible to the LXD
VM by using the expose command.
lxc exec k8s-vm -- sudo k8s kubectl expose deployment microbot --type=NodePort --port=80 --name=microbot-service
Get the assigned port. In this example, it’s 32750:
lxc exec k8s-vm -- sudo k8s kubectl get service microbot-service
…returns output similar to:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
microbot-service NodePort 10.152.183.188 <none> 80:32750/TCP 27m
With this, access Microbot from our host but using the VM’s address that we noted earlier.
curl 10.122.174.30:32750
Stop/remove the VM¶
The k8s-vm VM you created will keep running in the background until it is
either stopped or the host computer is shut down. Stop the running VM at any
time by running:
lxc stop k8s-vm
And it can be permanently removed with:
lxc delete k8s-vm