Django virtualenvwrapper environment variables in production - django

Question

I'm setting up a Django project on a server, following this guide on DigitalOcean. However, I'm very unfamiliar with Gunicorn and nginx, so I'm running into issues.
The server is running Ubuntu 18.04, Python 3.6.7, Django 2.1.3, virtualenvwrapper 4.8.4, gunicorn 19.9.0.
When running curl --unix-socket /run/gunicorn.sock localhost returns curl: (56) Recv failure: Connection reset by peer
I'm suspecting it is the way I handle the SECRET_KEY of Django.
I'm using virtualenvwrapper to handle my virtual environments and set environment variables in the postactivate and unset them in predeactivate in the following manner:
postactivate:
if [[ -n $SECRET_KEY ]]
then
export SECRET_KEY_BACKUP=$SECRET_KEY
fi
export SECRET_KEY='my-secret-key'
predeactivate:
if [[ -n $SECRET_KEY_BACKUP ]]
then
export SECRET_KEY=$SECRET_KEY_BACKUP
unset SECRET_KEY_BACKUP
else
unset SECRET_KEY
It's clear that the variables are not available unless the virtual env is activated. I retrieve the variables in settings.py with os.environ.get('SECRET_KEY').
How do gunicorn work with virtual environments? Is there a way to have gunicorn activate the environment?
Otherwise, what is best practice when it comes to the SECRET_KEY?
Thank you very much!
Edit: Added variable retrieval method.
Edit2: systemd service-file:
[Unit]
Description=gunicorn daemon
Requires=gunicorn.socket
After=network.target
[Service]
User=<name>
Group=www-data
WorkingDirectory=/home/<name>/projects/<projectname>/<appname>
ExecStart=/home/<name>/.virtualenvs/<appname>/bin/gunicorn \
--access-logfile - \
--workers 3 \
--bind unix:/run/gunicorn.sock \
<appname>.wsgi:application
[Install]
WantedBy=multi-user.target