frafra/k3s-tutorial

Personal notes - Learning how to use k3s

These notes are made mostly for myself, for didactical purposes. Pull requests are welcome.

Create a k3s cluster

...on Civo

civo k3s create test --remove-applications=traefik --nodes=1 --size=g2.xsmall --wait --save --switch

Traefik 2 is not supported on k3s; valid alternatives exist: k3s-io/k3s#817

...on VPS or bare metal

See: https://github.com/alexellis/k3sup

Deploy something on k3s

Preparation

Please be sure that your DNS is configured properly and install Helm.

Setup nginx

This step is required if Traefik has been removed.

helm repo add nginx-stable https://helm.nginx.com/stable
helm repo update
helm install nginx nginx-stable/nginx-ingress

Reference: https://docs.nginx.com/nginx-ingress-controller/installation/installation-with-helm/#installing-the-chart

Deploy a service

References:

• https://docs.nginx.com/nginx-ingress-controller/configuration/ingress-resources/basic-configuration/

kubectl apply -f is-osm-uptodate.yaml

Test if the service is reachable over HTTP.

Setup SSL

kubectl apply --validate=false -f https://github.com/jetstack/cert-manager/releases/download/v0.14.1/cert-manager.crds.yaml
kubectl create namespace cert-manager
helm repo add jetstack https://charts.jetstack.io
helm repo update
helm install \
  cert-manager jetstack/cert-manager \
  --namespace cert-manager \
  --version v0.14.1

References:

• https://cert-manager.io/docs/installation/kubernetes/#installing-with-helm

An alternative way to create a namespace is to apply the following YAML file:

apiVersion: v1
kind: Namespace
metadata:
  name: cert-manager

Setup letsencrypt

References:

• https://cert-manager.io/docs/configuration/acme/#creating-a-basic-acme-issuer
• https://letsencrypt.org/docs/acme-protocol-updates/#acme-v2-rfc-8555

kubectl apply -f letsencrypt-staging.yaml
kubectl apply -f letsencrypt.yaml

Use SSL

Uncomment the TLS section of is-osm-uptodate.yaml and the line referring to letsencrypt-staging, then update the deployment.

kubectl apply -f is-osm-uptodate.yaml

Try to connect over HTTPS and check if the fake certificate has been generated:

kubectl get secrets is-osm-uptodate-tls -o yaml | grep tls\.crt | awk '{ print $2 }' | base64 -d > cert
openssl x509 -in cert -text

Switch to the real letsencrypt certificate by commenting the line with letsencrypt-staging and uncommenting the following one, then update the deployment:

kubectl apply -f is-osm-uptodate.yaml