Hi Richard,
You can use other reverse proxies instead of Gluu docker-nginx. In fact, our Kubernetes distribution doesn't use docker-nginx in favor of Kubernetes Ingress.
Things to consider before using another reverse proxy:
1. TLS/SSL is needed at port 443
2. Rewrite rules are needed to conform to Gluu Server design. Examples: https://github.com/GluuFederation/community-edition-setup/blob/version_4.2.1/templates/https_gluu.conf, https://github.com/GluuFederation/docker-nginx/blob/4.2/templates/gluu_https.conf.ctmpl
Best regards,