Tell Oryx to configure gunicorn workers dynamically

[pamelafox]

Purpose

This PR enables PYTHON_ENABLE_GUNICORN_MULTIWORKERS on App Service. When Oryx sees that, it will auto configure gunicorn to use a worker count based off the formula of CPU_COUNT * 2 + 1. This should hopefully resolve issues like #272.

Here's Oryx docs about the config option:
https://github.com/microsoft/Oryx/blob/5239b0416cdddcf5bf0aef6703eb339efa865d67/doc/runtimes/python.md?plain=1#L101

The other approach is for us to specify our own startup script that does the same thing (as I describe in #272 (comment)), but for now, this is the quickest fix.

Does this introduce a breaking change?

[ ] Yes
[X] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[X] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

How to Test

• azd up
• Check Advanced Tools > Download as zip > default_docker.log, see that it spawned 3 workers
• Also SSH into App Service and check out /opt/startup/startup.sh, you'll see workers=3 in the command.

[pamelafox]

cc @jongio We may want to put this setting by default in core/host/appservice.bicep - the only reason its not default on Oryx is backwards compatibility issues.

[chip-davis]

Just chiming in that making this change fixed the issue I was having as mentioned in #272

[chuwik]

cc @jongio We may want to put this setting by default in core/host/appservice.bicep - the only reason its not default on Oryx is backwards compatibility issues.

+1 to making the change in core/host/appservice.bicep, feels like this should be specific to the app service config rather than in the main bicep file.

[vrajroutu]

@pamelafox Can you also look in to this? Adjust the number of workers based on the number of CPU cores

app/start.sh

#!/bin/sh  
  
echo ""  
echo "Loading azd .env file from current environment"  
echo ""  
  
while IFS='=' read -r key value; do  
    value=$(echo "$value" | sed 's/^"//' | sed 's/"$//')  
    export "$key=$value"  
done <<EOF  
$(azd env get-values)  
EOF  
  
if [ $? -ne 0 ]; then  
    echo "Failed to load environment variables from azd environment"  
    exit $?  
fi  
  
echo 'Creating python virtual environment "backend/backend_env"'  
python -m venv backend/backend_env  
  
echo ""  
echo "Restoring backend python packages"  
echo ""  
  
cd backend  
./backend_env/bin/python -m pip install -r requirements.txt  
if [ $? -ne 0 ]; then  
    echo "Failed to restore backend python packages"  
    exit $?  
fi  
  
echo ""  
echo "Restoring frontend npm packages"  
echo ""  
  
cd ../frontend  
npm install  
if [ $? -ne 0 ]; then  
    echo "Failed to restore frontend npm packages"  
    exit $?  
fi  
  
echo ""  
echo "Building frontend"  
echo ""  
  
npm run build  
if [ $? -ne 0 ]; then  
    echo "Failed to build frontend"  
    exit $?  
fi  
  
echo ""  
echo "Starting backend"  
echo ""  
  
cd ../backend  
xdg-open http://127.0.0.1:8000  
  
# Install gunicorn  
./backend_env/bin/pip install gunicorn  
  
# Adjust the number of workers based on the number of CPU cores  
workers=$(( $(nproc) * 2 ))  
  
# Start the backend using Gunicorn with multiple workers  
./backend_env/bin/gunicorn -w $workers -b 127.0.0.1:8000 app:app  
  
if [ $? -ne 0 ]; then  
    echo "Failed to start backend"  
    exit $?  
fi