I have initialized https://hub.docker.com/r/jboss/keycloak/ on my Digital Ocean Docker Droplet.
$docker run -e KEYCLOAK_USER=admin -e -p 8080:8080 KEYCLOAK_PA
Publish port 8443 (HTTPS) and use it instead of 8080 (HTTP):
docker run \
--name keycloak \
-e KEYCLOAK_USER=myadmin \
-e KEYCLOAK_PASSWORD=mypassword \
-p 8443:8443 \
jboss/keycloak
Keycloak generates self signed cert for https in this setup. Of course, this is not a production setup.
Update
Use volumes for own TLS certificate:
-v //tls.crt:/etc/x509/https/tls.crt \
-v //tls.key:/etc/x509/https/tls.key \