In my mesh, I am connecting to 3rd party services over TLS (specifically Strimzi's Kafka which is in the same k8 cluster, but w/o Istio sidecar). Normally I would install the certificate authority needed to the Java service, but with Istio terminating I'm not sure how to do so. If I put the public certificate in a secret, can I have a Secret Discovery Service (SDS) help manage it on the Envoy proxy (something like Secure Ingress SDS but for within the mesh)?
I've read this documentation, but it seems to be about replacing the generated certificates, which I don't want to do (I like the automatic maintenance within the cluster). https://istio.io/docs/tasks/security/plugin-ca-cert/
I have also added the 3rd party CAs as mounts to /etc as specified in this answer, but they aren't picked up by Envoy as certificates (checked via logs and istioctl tool).
How do you add additional certificate authorities to Istio Citadel so they are delivered to Envoy proxies in the security bundle?