How to configure the system traefik of k3os and perist the config over reboots

HOW_TO_change_and_persist_k3os_traefik_config.md

Problem: If you change the k3os traefik configuration in /var/lib/rancher/k3s/server/manifests/traefik.yaml directly, all changes will be lost after a reboot.

Solution:

1. sudo vi /var/lib/rancher/k3os/config.yaml
2. Add to the top level k3os part the following:

  k3s_args:
  - server
  - "--no-deploy=traefik"

3. Add the changed traefik configuration to the write_files section. This could be look like this:

write_files:
- content: |-
    apiVersion: helm.cattle.io/v1
    kind: HelmChart
    metadata:
      name: traefik
      namespace: kube-system
    spec:
      chart: https://%{KUBERNETES_API}%/static/charts/traefik-1.81.0.tgz
      set:
        rbac.enabled: "true"
        ssl.enabled: "true"
        ssl.enforced: "true"
        acme.enabled: "true"
        acme.challengeType: "tls-alpn-01"
        acme.email: "admin@yourdomain.com"
        acme.staging: "false"
        metrics.prometheus.enabled: "true"
        kubernetes.ingressEndpoint.useDefaultPublishedService: "true"
        image: "rancher/library-traefik"
  owner: root
  path: /var/lib/rancher/k3s/server/manifests/traefik.yaml
  permissions: '0755'

A complete config could look like this:

k3os:
  k3s_args:
  - server
  - "--no-deploy=traefik"
sshAuthorizedKeys:
- github:yourGithubUserName
write_files:
- content: |-
    apiVersion: helm.cattle.io/v1
    kind: HelmChart
    metadata:
      name: traefik
      namespace: kube-system
    spec:
      chart: https://%{KUBERNETES_API}%/static/charts/traefik-1.81.0.tgz
      set:
        rbac.enabled: "true"
        ssl.enabled: "true"
        ssl.enforced: "true"
        acme.enabled: "true"
        acme.challengeType: "tls-alpn-01"
        acme.email: "admin@yourdomain.com"
        acme.staging: "false"
        metrics.prometheus.enabled: "true"
        kubernetes.ingressEndpoint.useDefaultPublishedService: "true"
        image: "rancher/library-traefik"
  owner: root
  path: /var/lib/rancher/k3s/server/manifests/traefik.yaml
  permissions: '0755'

4. sudo k3os cfg --boot

Thats it.