docker-registry.tmpl

proxy_pass                       http://REGISTRY_PORT_5000_TCP_ADDR:REGISTRY_PORT_5000_TCP_PORT;
proxy_set_header  Host           $http_host;   # required for docker client's sake
proxy_set_header  X-Real-IP      $remote_addr; # pass on real client's IP
proxy_set_header  Authorization  "";
proxy_read_timeout               900;

docker.conf

# For going into conf.d/
server {
  listen       80;
  server_name  whatever.example.com;

  client_max_body_size      0;
  chunked_transfer_encoding on;

  location / {
    auth_basic            "Restricted";
    auth_basic_user_file  conf.d/htpasswd;

    # https://github.com/docker/distribution/issues/397
    add_header            Docker-Distribution-Api-Version registry/2.0 always;

    # We'll auto generate this file
    include               /docker-registry.conf;
  }
}

launch.sh

#!/bin/sh

cp /etc/nginx/conf.d/docker-registry.tmpl /docker-registry.conf
[ -z "${REGISTRY_PORT_5000_TCP_ADDR}" ] && echo "\$REGISTRY_PORT_5000_TCP_ADDR is not set" || sed -i "s/REGISTRY_PORT_5000_TCP_ADDR/${REGISTRY_PORT_5000_TCP_ADDR}/" /docker-registry.conf
[ -z "${REGISTRY_PORT_5000_TCP_PORT}" ] && echo "\$REGISTRY_PORT_5000_TCP_PORT is not set" || sed -i "s/REGISTRY_PORT_5000_TCP_PORT/${REGISTRY_PORT_5000_TCP_PORT}/" /docker-registry.conf

/usr/sbin/nginx -g "daemon off;"