Kubernetes will create all the objects and services for Rancher, but it will not become available until we populate the tls-rancher-ingress secret in the cattle-system namespace with the certificate and key.

Combine the server certificate followed by any intermediate certificate(s) needed into a file named tls.crt. Copy your certificate key into a file named tls.key.

For example, acme.sh provides server certificate and CA chains in fullchain.cer file. This fullchain.cer should be renamed to tls.crt & certificate key file as tls.key.

Use kubectl with the tls secret type to create the secrets.

kubectl -n cattle-system create secret tls tls-rancher-ingress \
  --cert=tls.crt \
  --key=tls.key

Note: If you want to replace the certificate, you can delete the tls-rancher-ingress secret using kubectl -n cattle-system delete secret tls-rancher-ingress and add a new one using the command shown above. If you are using a private CA signed certificate, replacing the certificate is only possible if the new certificate is signed by the same CA as the certificate currently in use.

Using a Private CA Signed Certificate

If you are using a private CA, Rancher requires a copy of the CA certificate which is used by the Rancher Agent to validate the connection to the server.

Copy the CA certificate into a file named cacerts.pem and use kubectl to create the tls-ca secret in the cattle-system namespace.

kubectl -n cattle-system create secret generic tls-ca \
  --from-file=cacerts.pem=./cacerts.pem

Note: The configured tls-ca secret is retrieved when Rancher starts. On a running Rancher installation the updated CA will take effect after new Rancher pods are started.