Restore mongodb database after all services have started

I have a docker-compose.yml file containing 2 services, one container for the meteorjs application and one container for my mongodb database.
This is my docker-compose.yml
version: ‘3’

services:
  app:
    image: myapp
    build:
      context: .
      dockerfile: Dockerfile
    volumes:
      - backup:/backup
    ports:
      - '3000:3000'
    depends_on:
      - mongo
    environment:
      ROOT_URL: ${APP_ROOT_URL:-http://application-url}
      MONGO_URL: mongodb://mongo:27017/meteor
      PORT: 3000
      NODE_ENV: production

  mongo:
    image: mongo:latest
    build:
      context: .
      dockerfile: mongo.Dockerfile
    command:
      - --storageEngine=wiredTiger
    volumes:
      - data:/data/db
      - backup:/backup
    ports:
      - '27017:27017'
    environment:
      MONGO_INITDB_DATABASE: meteor

volumes:
  data:
  backup:

Now, my application downloads a database (scp) into the /backup volume (I don’t have scp or ssh on the mongodb container).
Then, I have a script on my mongodb container that restores the database ( mongorestore ) using the database in /backup.

My problem is that the database in /backup is not available when the mongodb container is started, I tried creating a separate Dockerfile for my mongodb container

FROM mongo

COPY ./sync-prod-with-ci-db.sh /docker-entrypoint-initdb.d/sync-prod-with-ci-db.sh

RUN chmod 777 /docker-entrypoint-initdb.d/sync-prod-with-ci-db.sh

The above Dockerfile comes following the official Mongo Docker Documentation, unfortunately that doesn’t work too (should it work? am I missing something here?)

When a container is started for the first time it will execute files with extensions .sh and .js that are found in /docker-entrypoint-initdb.d . Files will be executed in alphabetical order. .js files will be executed by mongo using the database specified by the MONGO_INITDB_DATABASE variable, if it is present, or test otherwise. You may also switch databases within the .js script.

My sync-prod-with-ci-db.sh script :

#!/usr/bin/env bash

DB_SNAPSHOT_NAME='database-snapshot.tar.gz'

echo "Restoring prod DB snapshot to Mongo Container ..."

tar -xzvf /backup/${DB_SNAPSHOT_NAME}

mongorestore -h 127.0.0.1 --drop -d meteor ./backup/my_database

How can I run the sync-prod-with-ci-db.sh script AFTER both the mongo and the myapp containers have started? I would like for it to be done automatically when I run docker-compose up -d --build

PS: IF I RUN THE SCRIPT MANUALLY IT WORKS