kube-lego: Automatically provision TLS certificates in Kubernetes

kube-lego automatically requests certificates for Kubernetes Ingress resources from Let's Encrypt.

ref:
https://github.com/jetstack/kube-lego
https://letsencrypt.org/

I run kube-lego v0.1.5 with Kubernetes v1.9.4, everything works very fine.

Deploy kube-lego

It is strongly recommended to try Let's Encrypt Staging API first.

# kube-lego/deployment.yaml
kind: Namespace
apiVersion: v1
metadata:
  name: kube-lego
---
kind: ConfigMap
apiVersion: v1
metadata:
  name: kube-lego
  namespace: kube-lego
data:
  LEGO.EMAIL: "[email protected]"
  # LEGO.URL: "https://acme-v01.api.letsencrypt.org/directory"
  LEGO.URL: "https://acme-staging.api.letsencrypt.org/directory"
---
kind: Deployment
apiVersion: apps/v1
metadata:
  name: kube-lego
  namespace: kube-lego
spec:
  replicas: 1
  selector:
    matchLabels:
      app: kube-lego
  template:
    metadata:
      labels:
        app: kube-lego
    spec:
      containers:
      - name: kube-lego
        image: jetstack/kube-lego:0.1.5
        ports:
        - containerPort: 8080
        env:
        - name: LEGO_LOG_LEVEL
          value: debug
        - name: LEGO_EMAIL
          valueFrom:
            configMapKeyRef:
              name: kube-lego
              key: LEGO.EMAIL
        - name: LEGO_URL
          valueFrom:
            configMapKeyRef:
              name: kube-lego
              key: LEGO.URL
        - name: LEGO_NAMESPACE
          valueFrom:
            fieldRef:
              fieldPath: metadata.namespace
        - name: LEGO_POD_IP
          valueFrom:
            fieldRef:
              fieldPath: status.podIP
        readinessProbe:
          httpGet:
            path: /healthz
            port: 8080
          initialDelaySeconds: 5
          timeoutSeconds: 1

ref:
https://github.com/jetstack/kube-lego/tree/master/examples

$ kubectl apply -f kube-lego/ -R

Configure the Ingress

  • Add an annotation kubernetes.io/tls-acme: "true" to metadata.annotations
  • Add domains to spec.tls.hosts.

spec.tls.secretName is the Secret used to store the certificate received from Let's Encrypt, i.e., tls.key and tls.crt. If no Secret exists with that name, it will be created by kube-lego.

# ingress.yaml
kind: Ingress
apiVersion: extensions/v1beta1
metadata:
  name: simple-project
  annotations:
    kubernetes.io/ingress.class: "gce"
    kubernetes.io/tls-acme: "true"
spec:
  tls:
  - secretName: kittenphile-com-tls
    hosts:
    - kittenphile.com
    - www.kittenphile.com
    - api.kittenphile.com
  rules:
  - host: kittenphile.com
    http:
      paths:
      - path: /*
        backend:
          serviceName: simple-frontend
          servicePort: http
  - host: www.kittenphile.com
    http:
      paths:
      - path: /*
        backend:
          serviceName: simple-frontend
          servicePort: http
  - host: api.kittenphile.com
    http:
      paths:
      - path: /*
        backend:
          serviceName: simple-api
          servicePort: http

ref:
https://kubernetes.io/docs/concepts/services-networking/ingress/#tls

$ kubectl apply -f ingress.yaml

You could find exact ACME challenge paths by inspecting your Ingress resource.

$ kubectl describe ing simple-project
...
TLS:
  kittenphile-com-tls terminates kittenphile.com,www.kittenphile.com,api.kittenphile.com
Rules:
  Host                 Path  Backends
  ----                 ----  --------
kittenphile.com
                       /.well-known/acme-challenge/*   kube-lego-gce:8080 (<none>)
                       /*                              simple-frontend:http (<none>)
www.kittenphile.com
                       /.well-known/acme-challenge/*   kube-lego-gce:8080 (<none>)
                       /*                              simple-frontend:http (<none>)
api.kittenphile.com
                       /.well-known/acme-challenge/*   kube-lego-gce:8080 (<none>)
                       /*                              simple-api:http (<none>)
...

You might want to see logs of kube-lego Pods for observing the progress.

$ kubectl logs -f deploy/kube-lego --namespace kube-lego

Create a Production Certificate

After you make sure everything works ok, you are able to request production certificates for your domains.

Follow these instructions:

  • Change LEGO_URL to https://acme-v01.api.letsencrypt.org/directory
  • Delete account secret kube-lego-account
  • Delete certificate secret kittenphile-com-tls
  • Restart kube-lego
$ kubectl get secrets --all-namespaces
$ kubectl delete secret kube-lego-account --namespace kube-lego && \
  kubectl delete secret kittenphile-com-tls

$ kubectl replace --force -f kube-lego/ -R
$ kubectl logs -f deploy/kube-lego --namespace kube-lego

ref:
https://github.com/jetstack/kube-lego#switching-from-staging-to-production

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