How to launch gunicorn inside Docker

gunicorn-docker-start.sh

#!/bin/bash
#
# Start backend using Gunicorn web server.
#
# - Run as a standalone UNIX daemon
# - Run inside a Docker container
# - Read config file for more settings that cannot be given on command line
#
# See https://docs.gunicorn.org/en/stable/settings.html
#

# https://stackoverflow.com/a/25518345/315168
if [ -f /.dockerenv ]; then
    # Launched within Docker
    echo "Launching as a Docker container"
    LISTEN=0.0.0.0:3456
else
    echo "Launching as a UNIX daemon"
    # Launched standalone,
    # assume prod server
    LISTEN=127.0.0.1:3456
fi

gunicorn \
  --name backend \
  --config=gunicorn-config.py \
  --bind $LISTEN \
  --preload \
  --workers 16 \
  --threads 2 \
  --timeout 30 \
  --max-requests 500 \
  --env "SCRIPT_NAME=/api" \
  --access-logfile logs/gunicorn_access.log \
  --error-logfile logs/gunicorn_error.log \
  "backend.server.server:gunicorn_entry_point()"

echo "gunicorn exited, exit code $?"