To use TLS client authentication, set the `type` property to the value `tls`.
TLS client authentication uses a TLS certificate to authenticate.
The certificate is specified in the `certificateAndKey` property and is always loaded from a Kubernetes secret.
In the secret, the certificate must be stored in X509 format under two different keys: public and private.

NOTE: TLS client authentication can only be used with TLS connections.

.An example TLS client authentication configuration
[source,yaml,subs=attributes+]
----
authentication:
  type: tls
  certificateAndKey:
    secretName: my-secret
    certificate: public.crt
    key: private.key
----
