Heroku

Install Git and the Heroku CLI and log in using heroku login.

Then follow this guide to set up and deploy with Git:

# creat the app
heroku create -a python-shiny
# check that the heroku remote is added
git remote -v

Now we use the heroku.yml as our manifest to build the Docker image on Heroku:

# set the stack of your app to container:
heroku stack:set container

Check in your commits, then git push heroku main. This will build the image and deploy your app on Heroku.

Get the app URL from heroku info, then check the app.

Scaling on Heroku

heroku features:enable http-session-affinity

Change dyno type to allow scaling to >1:

# change dyno type 
heroku ps:type web=standard-1x

Scale the number of web dynos to 2:

heroku ps:scale web=2

It should say Status: Test complete.

Now let's disable session affinity:

heroku features:disable http-session-affinity

Visit the app URL again, refresh, and you'll see Status: Failure!.

Delete the app from the dashboard or use heroku apps:destroy --confirm=python-shiny (this will remove the git remote as well).

For the R version, edit the heroku.yml to use Dockerfile.lb-r:

build:
  docker:
    web: Dockerfile.lb-r

You can now repeat the steps above.