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Setting up SSL using cert-manager through HTTP-01 challenge

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In this page we will see how can we create SSL certificate using cert-manager through HTTP-01 challenge

What are HTTP-01 and DNS-01 challenge ?

The DNS-01 and HTTP-01 challenges are two methods used in the ACME (Automated Certificate Management Environment) protocol for validating domain ownership when requesting SSL/TLS certificates, typically for securing websites.

DNS-01 challenge involves creating a DNS TXT record with a specific value provided by the certificate authority (CA) to prove domain ownership. This method is usually preferred when automating certificate issuance because it doesn't require a publicly accessible web server but does require control over the domain's DNS records.

On the other hand, HTTP-01 challenge requires hosting a specific file with a token provided by the CA on the web server associated with the domain. The CA performs an HTTP request to verify that the token exists at a specific URL, confirming domain ownership. This method is suitable for domains with web servers that are publicly accessible.

Why HTTP-01 ?

It is sometimes not possible to pass the authentication keys of the DNS server to cert-manager to perform DNS-01 challenge. For cases like these a web server can be hosted in the kubernetes cluster through which HTTP-01 challenge can be completed and certificate can be generated.

Generating Certificate Cert-manager and Istio.

  1. Make sure cert-manager is installed in the cluster. For this head over to the Integrations tab, click on the three dots on your cluster card.

  2. Click Manage Applications and install cert-manager.

  3. Export these variables 

    export DOMAIN="" # enter your domain name here, can't we wildcard as it is not supported for HTTP-01 challenge
export EMAIL=""

  4. Create the Issuer with http01 challenge. Issuer should be created in istio-system namespace only.

    k apply -f -<<EOF
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: letsencrypt-prod-cluster
  namespace: istio-system
spec:
  acme:
    email: $EMAIL
    server: https://acme-v02.api.letsencrypt.org/directory
    privateKeySecretRef:
      name: letsencrypt-prod-cluster
    solvers:
    - http01:
        ingress:
          class: istio
EOF

  5. Create the certificate. Certificate should be created in istio-system namespace only.

    k apply -f -<<EOF
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
  name: letsencrypt-prod-cert
  namespace: istio-system
spec:
  secretName: letsencrypt-prod-secret
  duration: 2160h # 90d
  renewBefore: 360h # 15d
  isCA: false
  privateKey:
    algorithm: RSA
    encoding: PKCS1
    size: 2048
  usages:
    - server auth
    - client auth
  dnsNames:
    - "$DOMAIN"
  issuerRef:
    name: letsencrypt-prod-cluster
EOF

  6. The certificate will be in False state 

    kubectl get certificates.cert-manager.io -n istio-system
NAME                    READY   SECRET                   AGE
letsencrypt-prod-cert   False   letsencrypt-prod-secret   12m

  7. This will create a pod, service and an ingress in istio-system namespace. 

    kubectl get pods,svc,ing -n istio-system -l acme.cert-manager.io/http01-solver=true

  8. We need to copy the service name and the port number from this ingress 

    SERVICE_NAME=$(kubectl get ing -n istio-system -l  acme.cert-manager.io/http01-solver=true  -ojsonpath='{.items[0].spec.rules[0].http.paths[0].backend.service.name}')
PORT_NUMBER=$(kubectl get ing -n istio-system -l  acme.cert-manager.io/http01-solver=true  -ojsonpath='{.items[0].spec.rules[0].http.paths[0].backend.service.port.number}')

  9. We need to create a VirtualService object with the ingress details 

    k apply -f -<<EOF
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: letsencrypt-prod-vs
  namespace: istio-system
spec:
  hosts:
  - "$DOMAIN"
  gateways:
  - istio-system/tfy-wildcard
  http:
  - match:
    - uri:
        prefix: /
    rewrite:
      uri: /
    route:
    - destination:
        host: SERVICE_NAME
        port:
          number: $PORT_NUMBER
EOF

  10. Now we will edit tfy-istio-ingress in Deployments tab under Helm section.

    1. Make suretfy-istio-ingress is running.

    2. Edit tfy-istio-ingress to check if httpsRedirect is set to false

    3. Edit the HTTPS section of the gateway to credentialName to have the value of spec.secretName of the certificate we created above. Keep the protocol for tls[1] to HTTPS

      tfyGateway:
  name: tfy-wildcard
  spec:
    servers:
      - tls:
          httpsRedirect: false
        port:
          name: http-tfy-wildcard
          number: 80
          protocol: HTTP
        hosts:
          - $DOMAIN
      - tls:
          mode: SIMPLE
          credentialName: letsencrypt-prod-secret
        port:
          name: https-tfy-wildcard
          number: 443
          protocol: HTTPS
        hosts:
          - $DOMAIN
    selector:
      istio: tfy-istio-ingress

  11. Once this is done we need to create a DNS record in the DNS server to allow $DOMAIN to point to the load balancer created by the cloud provider. To get the IP or the hostname, run the below command 

    kubectl get svc tfy-istio-ingress -n istio-system
NAME                TYPE           CLUSTER-IP    EXTERNAL-IP      PORT(S)                                      AGE
tfy-istio-ingress   LoadBalancer   10.0.58.231   <YOUR-IP-HERE>   15021:30547/TCP,80:32123/TCP,443:30997/TCP   11h

  12. Once this is done we will wait for the certificate to get in the ready state.

  13. Once the certificate gets in the ready state, we can edit the httpsRedirect: true

Updated 8 months ago