You can provide your own CA and certificates instead of the self-signed certificate to connect to Elasticsearch via HTTPS using a Kubernetes secret. The certificate must be stored under tls.crt and the private key must be stored under tls.key. If your certificate was not issued by a well-known CA, you must include the trust chain under ca.crt as well.

You need to reference the name of a secret that contains a TLS private key and a certificate (and optionally, a trust chain), in the spec.http.tls.certificate section.

spec:
  http:
    tls:
      certificate:
        secretName: my-cert

This is an example on how to create a Kubernetes TLS secret with a self-signed certificate:

$ openssl req -x509 -sha256 -nodes -newkey rsa:4096 -days 365 -subj "/CN=quickstart-es-http" -addext "subjectAltName=DNS:quickstart-es-http.default.svc" -keyout tls.key -out tls.crt
$ kubectl create secret generic my-cert --from-file=ca.crt=tls.crt --from-file=tls.crt=tls.crt --from-file=tls.key=tls.key