docker – nginx: [emerg] invalid variable name

I’m having a problem using an environment variable in nginx.conf using docker-compose and dockerFile

I get the following error:

nginx: [emerg] invalid variable name in /etc/nginx/nginx.conf:291

The problem line:

 set_hmac_sha1 $sig "$SECRET_KEY" "$cookie_sessionid $stream_username";

My dockerFile sets SECRET KEY the following way —>

Environment variable for re-authorization:

ENV SECRET_KEY=${SECRET_KEY}

My docker-compose links to:

env_file:
      - .docker-compose.env

My .docker-compose.env file finally defines the SECRET_KEY variable:

SECRET_KEY= "this is the Django secret_key"

I have an entrypoint.sh which I use has the following 2 lines at the bottom one of them which is the envsubst:

envsubst "$(env | sed -e 's/=.*//' -e 's/^/\$/g')" < \
  /etc/nginx/nginx.conf.template > /etc/nginx/nginx.conf

nginx -g 'daemon off;'

Also, maybe just for mentioning it–>

I Copy the custom nginx.conf to the container:

COPY nginx.conf /etc/nginx/nginx.conf.template