I've got similar issue recently when connecting Quarkus to my ELK instance with TLS. Quarkus application needs a truststore to validate ELK server's certificate.

And your error may be due to SSLContext error, as even if you configure quarkus.tls.trust-all=true, your elk client may bypass this config and set its own SSLContext, which needs a certificate validation. I can be wrong.

First, you need to set your Elasticsearch cluster following this documentation : https://www.elastic.co/guide/en/elasticsearch/reference/6.8/configuring-tls.html#node-certificates and retrieve the Elasticsearch certificate from your instance.

If needed, you can check with openssl if the certificate is valid:

openssl x509 -in /path/to/elastic-stack-ca.crt -text -noout

Once it's done, import it into a trust-store (instead of the key-store) with keytool:

keytool -import -file elk.crt -alias elk -keystore truststore.p12 -storetype PKCS12 -storepass somePassword

Then update your Quarkus config:

quarkus:
  tls:
    trust-store:
      p12:
        path: /someAbsoultePath/truststore.p12
        password: somePassword