Configuring HTTPS with a custom certificate

If you already have an SSL/TLS certificate for your domain you can follow the steps below to configure Knative to use your certificate and enable HTTPS connections.

Before you begin, you will need to configure Knative to use your custom domain.

Note: due to limitations in Istio, Knative only supports a single certificate per cluster. If you will serve multiple domains in the same cluster, make sure the certificate is signed for all the domains.

Add the Certificate and Private Key into a secret

Note, if you don’t have a certificate, you can find instructions on obtaining an SSL/TLS certificate using LetsEncrypt at the bottom of this page.

Assuming you have two files, which contains your certificate private key, and cert.pem which contains the public certificate, you can use the following command to create a secret that stores the certificate. Note the name of the secret, istio-ingressgateway-certs is required.

kubectl create --namespace istio-system secret tls istio-ingressgateway-certs \
  --key \
  --cert cert.pem

Configure the Knative shared Gateway to use the new secret

Once you have created a secret that contains the certificate, you need to update the Gateway spec to use the HTTPS.

To edit the shared gateway, run:

kubectl edit gateway knative-ingress-gateway --namespace knative-serving

Change the Gateway spec to include the tls: section as shown below, then save the changes.

# Please edit the object below. Lines beginning with a '#' will be ignored.
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
kind: Gateway
  # ... skipped ...
    knative: ingressgateway
    - hosts:
        - "*"
        name: http
        number: 80
        protocol: HTTP
    - hosts:
        - "*"
        name: https
        number: 443
        protocol: HTTPS
        mode: SIMPLE
        privateKey: /etc/istio/ingressgateway-certs/tls.key
        serverCertificate: /etc/istio/ingressgateway-certs/tls.crt

Once the change has been made, you can now use the HTTPS protocol to access your deployed services.

Obtaining an SSL/TLS certificate using Let’s Encrypt through CertBot

If you don’t have an existing SSL/TLS certificate, you can use Let’s Encrypt to obtain a certificate manually.

Warning: Certificates issued by Let’s Encrypt are only valid for 90 days. You must renew your certificate with the certbot tool again every 90 days.

  1. Install the certbot-auto script from the Certbot website.
  2. Use the certbot to request a certificate, using DNS validation. The certbot tool will walk you through validating your domain ownership by creating TXT records in your domain.
   ./certbot-auto certonly --manual --preferred-challenges dns -d '*'
  1. When certbot is complete, you will have two output files, privkey.pem and fullchain.pem. These files map to the and cert.pem files used above.

Obtaining an SSL/TLS certificate using LetsEncrypt with cert-manager

You can also use cert-manager to automate the steps required to generate a TLS certificate using LetsEncrypt.

Install cert-manager

To install cert-manager into your cluster, use kubectl to apply the cert-manager manifest:

kubectl apply --filename

or see the cert-manager docs for more ways to install and customize.

Configure cert-manager for your DNS provider

Once you have installed cert-manager, you’ll need to configure it for your DNS hosting provider.

Knative currently only works with the DNS01 challenge type for LetsEncrypt, which is only supported by a small number of DNS providers through cert-manager.

Instructions for configuring cert-manager are provided for the following DNS hosts:

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