Backend Documentation

Start Server

To start the Flask server, we will first create or attach to a tmux session. First, check to see if there is an existing tmux server session using the following command:

tmux list-sessions

If there are no sessions running, we will start a new tmux server session as follows:

tmux new -s server

If there is already a session running, we can connect to it directly:

tmux attach-session -t server

Once inside the tmux server session, we will want to enter our virtual environment containing dependencies for running the web server. If a local virtual environment hasn't yet been set up, the following commands can be used at the root backend directory to do so:

python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

This virtual environment can be released at any time by using the following command:

deactivate

Finally, we will initialize the Flask web server application by using Gunicorn, a portable WSGI (Web Server Gateway Interface). The Gunicorn launcher will automatically import configuration settings from the conf/gunicorn.conf.py file and spool up the Flask application in main.py. This can be done with the following command (inside tmux and within the virtual environment from above):

venv/bin/gunicorn main:app -c conf/gunicorn.conf.py

env/bin/gunicorn main:app -c conf/gunicorn.conf.py

Stop Server

Safely shutting down the web server can be done by simply attaching to the tmux session as illustrated above and entering CTRL+C. Note that the tmux server should not be externally shut down or killed as this will result in the background Gunicorn workers being orphaned (which can only be cleared out by restarting the instance or manually sending a SIGKILL to the worker PIDs).