From 0 to Kubernetes – Step 2, deploying K3s

The next step is to install K3s, which is simple enough:

• log in to your app server as your local user
• run the following command:

  sudo curl -sfL https://get.k3s.io | sh -s - --disable=traefik
  

• have some patience.

Once this is done you can see the status of your “cluster” with “kubectl get nodes”:

lemmy@akari:~> kubectl get nodes
NAME STATUS ROLES AGE VERSION
appsrv Ready control-plane,master 7d22h v1.20.4+k3s1

One thing worth talking about is –disable=traefik which I’ll do in the next part.

Let me just mention this page, which helped me a lot at this point.

Now there are some little tweaks that you might want to consider doing:

• Disabling IPv6 on your appserver:
  I found that after a reboot some of the services on my appserver would fail to start properly. In the system journal I could see them complain about invalid certificates, and on closer inspection I found that the pods tried to talk to each other using IPv6, but the self-signed certificates that K3s had generated didn’t include the right IPv6 information. The fix was simple enough, create a file /etc/sysctl.d/98-disable-ipv6.conf with a single line in it: “net.ipv6.conf.all.disable_ipv6=1”, then restart the server and you’ll find all pods running properly now.
• Making your K3s accessible for the regular local user without having to use sudo:
  By default the configuration files in /etc/rancher are only readable for root, so the local unprivileged user needs sudo. That can get a bit annoying, because a lot of tutorials that you’ll might want to follow once your K3s is up and running only mention the “naked” kubectl commands, so if you copy&paste them they’ll fail. Solution: create the environment file for the k3s service in /etc/systemd/system/k3s.service.env and put one line in it:

  mathias@appsrv:~$ sudo cat /etc/systemd/system/k3s.service.env
  K3S_KUBECONFIG_MODE="644"

  After a restart of K3s you should be able to use kubectl as the regular user without sudo.

• Make your K3s accessible from other hosts, i.e. your desktop computer:
  Once your regular user on your k3s host can use kubectl without sudo you can then copy the config file ~/.kube/config to other hosts and install kubectl on those. Make sure you edit that config file and change the server url to point at the right IP address.

Continued here.