How do I do a correct reverse-proxy to a Redis instance?

Question

I'm running an application called Ambar on a (Samba)fileserver. I want users in my network to be able to search for documents freely, and securely. Since Ambar runs on HTTP, and the server already has Apache on it from before, I decided to set up a reverse proxy to Ambar through port 443. Should be quite straight-forward, one might think, but no, apparently Ambar (running on Redis) says the following:

Possible SECURITY ATTACK detected. It looks like somebody is sending POST or Host: commands to Redis. This is likely due to an attacker attempting to use Cross Protocol Scripting to compromise your Redis instance. Connection aborted. (taken from docker-compose logs).

I can reach the app's GUI, but I can't do anything there. That's a good thing anyway, since at least I know it's not a certificate issue..

This is my Apache-config:

LoadModule ssl_module modules/mod_ssl.so


<VirtualHost *:443>
    ServerName ambar.internal

    ProxyPreserveHost On
    ProxyPass / http://ambar.internal:1000/
    ProxyPassReverse / http://ambar.internal:1000/

    SSLEngine on
    SSLCertificateFile /etc/ssl/certs/ambar.crt
    SSLCertificateKeyFile /etc/ssl/private/ambar.pem
</VirtualHost>

Edit: reverse-proxying with SSL/TLS activated from another machine does not work either.

Making manual modifications of Ambar packages isn't a great idea as the whole app comes with ready Docker containers. So my next attempt is to set up SSL in the docker-compose.yml file, but shouldn't there be a way to accomplish this with good-ol' reverse proxying?

Here is my docker-compose.yml:

version: "2.1"
networks:
  internal_network:
services:
  db:
    restart: always
    networks:
      - internal_network
    image: ambar/ambar-mongodb:latest
    environment:
      - cacheSizeGB=2
    volumes:
      - /opt/ambar/db:/data/db
    expose:
      - "27017"
  es:
    restart: always
    networks:
      - internal_network
    image: ambar/ambar-es:latest
    expose:
      - "9200"
    environment:
      - cluster.name=ambar-es
      - ES_JAVA_OPTS=-Xms2g -Xmx2g
    ulimits:
      memlock:
        soft: -1
        hard: -1
      nofile:
        soft: 65536
        hard: 65536
    cap_add:
      - IPC_LOCK
    volumes:
      - /opt/ambar/es:/usr/share/elasticsearch/data
  rabbit:
    restart: always
    networks:
      - internal_network
    image: ambar/ambar-rabbit:latest
    hostname: rabbit
    expose:
      - "15672"
      - "5672"
    volumes:
      - /opt/ambar/rabbit:/var/lib/rabbitmq
  redis:
    restart: always
    sysctls:
      - net.core.somaxconn=1024
    networks:
      - internal_network
    image: ambar/ambar-redis:latest
    expose:
      - "6379"
  serviceapi:
    depends_on:
      redis:
        condition: service_healthy
      rabbit:
        condition: service_healthy
      es:
        condition: service_healthy
      db:
        condition: service_healthy
    restart: always
    networks:
      - internal_network
    image: ambar/ambar-serviceapi:latest
    expose:
      - "8081"
    environment:
      - mongoDbUrl=mongodb://db:27017/ambar_data
      - elasticSearchUrl=http://es:9200
      - redisHost=redis
      - redisPort=6379
      - rabbitHost=amqp://rabbit
      - langAnalyzer=ambar_en
  webapi:
    depends_on:
      serviceapi:
        condition: service_healthy
    restart: always
    networks:
      - internal_network
    image: ambar/ambar-webapi:latest
    expose:
      - "8080"
    ports:
      - "8080:8080"
    environment:
      - uiLang=en
      - mongoDbUrl=mongodb://db:27017/ambar_data
      - elasticSearchUrl=http://es:9200
      - redisHost=redis
      - redisPort=6379
      - serviceApiUrl=http://serviceapi:8081
      - rabbitHost=amqp://rabbit
  frontend:
    depends_on:
      webapi:
        condition: service_healthy
    image: ambar/ambar-frontend:latest
    restart: always
    networks:
      - internal_network
    ports:
      - "1000:80"
    expose:
      - "1000"
    environment:
      - api=http://192.168.123.123:8080
  pipeline0:
    depends_on:
      serviceapi:
        condition: service_healthy
    image: ambar/ambar-pipeline:latest
    restart: always
    networks:
      - internal_network
    environment:
      - id=0
      - apiUrl=http://serviceapi:8081
      - rabbit_host=amqp://rabbit
  documentation:
    depends_on:
      serviceapi:
        condition: service_healthy
    image: ambar/ambar-local-crawler
    restart: always
    networks:
      - internal_network
    expose:
      - "8082"
    environment:
      - name=documentation
      - ignoreExtensions=.{exe,dll,rar,s,so}
      - apiUrl=http://serviceapi:8081
    volumes:
      - /media/Documentation:/usr/data