Wildcard Let's Encrypt certs on Kubernetes with Traefik

Ingredients

For this recipe we will need:

• A VPS instance or other server preferably with 1GB ram
• AWS Route 53 DNS zone
• A kubernetes cluster. In our case k3s
• cert-manager

Steps

1. First get a server 😄 Scaleway, Amazon Lightsail, DigitalOcean and Vultr are among the popular and affordable choices. You can get a decent VPS for as less as maybe 6$/mo (at the time of this writing) that will easily get the job done.

2. Choose your favorite distro. This exercise has been done on Ubuntu 18.04 but other distros will also work fine. Just pick your favorite one and install your k3s server.

3. Head over to k3s.io and follow the recommended method to install a single node k3s directly on your host.
   

   bash

   curl -sfL https://get.k3s.io | sh -
   # Check for Ready node, takes maybe 30 seconds
   k3s kubectl get node  

4. Since k3s comes with traefik ingress controller baked-in, you can go ahead and create an ingress for your domain right away. This example from the documentation will get you started.

   traefik UI service & ingress yaml

   apiVersion: v1
   kind: Service
   metadata:
     name: traefik-web-ui
     namespace: kube-system
   spec:
     selector:
       k8s-app: traefik-ingress-lb
     ports:
     - name: web
       port: 80
       targetPort: 8080
   ---
   apiVersion: extensions/v1beta1
   kind: Ingress
   metadata:
     name: traefik-web-ui
     namespace: kube-system
   spec:
     rules:
     - host: traefik-ui.minikube
       http:
         paths:
         - path: /
           backend:
             serviceName: traefik-web-ui
             servicePort: web
             

5. Create your DNS record sets to match your domain and static IP on AWS Route 53. While you are here note your AWS_HOSTED_ZONE_ID

6. In the IAM console of AWS create a user with administrator access to your AWS account.

7. Note the AWS_ACCESS_KEY_ID & the AWS_SECRET_ACCESS_KEY for the account you created in the previous step.

8. Deploy Cert-manager on your cluster

9. Configure DNS01 challenge (recommended)

10. You should end up with an Issuer yaml file like this. Apply and enjoy 🎉

apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
...
spec:
acme:
...
solvers:
- selector:
  dnsZones:
  - 'example.com'
- dns01:
  # Valid values are None and Follow
  cnameStrategy: Follow
  route53:
    region: eu-central-1
    accessKeyID: <Access ID for less-privileged.example.org here>
    hostedZoneID: <Zone ID for less-privileged.example.org here>
    secretAccessKeySecretRef:
      ...