OCIS preview with ssl accelerator in front

I have a running ocis preview 1.6 with haproxy as ssl accelerator in front. The config is the same as for a test installation of hugo (https://gohugo.io/). The OCIS answer on p. 9200:

Client sent an HTTP request to an HTTPS server.

I assume the preview has builtin ssl with self-signed certs?
Is it possible to run the preview without ssl and get the ssl stuff from “outside”?
(haproxy with port forwarding from 443 to localhost:9200)

Sorry for the late answer.

You guessed right that oCIS is doing SSL out of the box.

You can disable it by setting this environment variable before starting oCIS:

export PROXY_TLS=false