How to configure standalone confluent rest proxy

Question

I am running the standalone confluent kafka rest proxy from a docker image as described here. I also see the configuration options described here

My question is: how, or where, do I set the configuration options so that the proxy running in the docker container sees them?

I read the documentation but don't see how to add configuration options to the docker image.

I am using this docker compose yml:

---
version: '2'
services:

  rest-proxy:
    image: confluentinc/cp-kafka-rest:7.5.0
    ports:
      - 8082:8082
    hostname: rest-proxy
    container_name: rest-proxy
    environment:
      KAFKA_REST_HOST_NAME: rest-proxy
      KAFKA_REST_LISTENERS: "http://0.0.0.0:8082"
      KAFKA_REST_BOOTSTRAP_SERVERS: $BOOTSTRAP_SERVERS
      KAFKA_REST_SECURITY_PROTOCOL: "$SECURITY_PROTOCOL"
      KAFKA_REST_SASL_JAAS_CONFIG: $SASL_JAAS_CONFIG
      KAFKA_REST_SASL_MECHANISM: $SASL_MECHANISM
      KAFKA_REST_CLIENT_BOOTSTRAP_SERVERS: $BOOTSTRAP_SERVERS
      KAFKA_REST_CLIENT_SECURITY_PROTOCOL: "SASL_SSL"
      KAFKA_REST_CLIENT_SASL_JAAS_CONFIG: $SASL_JAAS_CONFIG
      KAFKA_REST_CLIENT_SASL_MECHANISM: $SASL_MECHANISM