Problem/ Help needed with variable interpolation

1

I am trying to deploy my docker-based project, which encompasses multiple services (django, postgres, celery, redis, flower). I would like to use my Redis instance with two separate databases.

On my local machine I achieve this via the env vars CELERY_BROKER_URL=redis://redis:6379/1 and CACHE_URL redis://redis:6379/2.

For deployment on render, I tried the following in my render.yaml file

    - key: REDIS_URL
      fromService:
        name: redis
        type: redis
        property: connectionString
    - key: CELERY_BROKER_URL
      value: ${REDIS_URL}/1
    - key: CACHE_URL
      value: ${REDIS_URL}/2

However, as I’ve read later in the docs, variable interpolation does not work in render.yaml files yet and a workaround is to write start script that does the variable interpolation.

So I wrote the following redis_setup.sh script:

#!/bin/bash

# Get the Redis URL
BASE_URL=$REDIS_URL

# Create new environment variables with database numbers
export CELERY_BROKER_URL="${BASE_URL}/1"
export CACHE_URL="${BASE_URL}/2"

# Print the environment variables to verify they are set correctly
echo "Environment variables set:"
echo "BASE_URL: $BASE_URL"
echo "CELERY_BROKER_URL: $CELERY_BROKER_URL"
echo "CACHE_URL: $CACHE_URL"

which is then executed by the following startup.sh script:

#!/bin/bash
. /redis_setup.sh
python manage.py migrate
python manage.py collectstatic --noinput
exec gunicorn config.wsgi

which I use in the render.yaml , in the web service in dockerCommand: "/startup.sh"

When I check the logs of my web service after a deployment, I can see the values of CELERY_BROKER_URL and CACHE_URL printed out as expected as interpolated strings but I can’t see them in the “Environment Variables” in the dashboard on Tender nor if I start a shell session and run printenv nor can I access them in any other way.

What am I missing? How can I have Render pick up the two environment variables created in the script?

Many thanks in advance!