First you need to set this buildpack as your initial buildpack with:
$ heroku buildpacks:add -i 1 https://github.com/heroku/heroku-buildpack-l2met-shuttle.git
You also need to define the URL of your L2met compatible endpoint:
$ heroku config:set L2MET_SHUTTLE_URL=<url>
Next, for each process that emit metrics, you will need to preface the command in your Procfile with
start-l2met-shuttle. In this example, we want only the web process to send metrics through
$ cat Procfile web: ./bin/start-l2met-shuttle bundle exec unicorn -p $PORT -c ./config/unicorn.rb -E $RACK_ENV worker: bundle exec rake worker
Rebuild your app for the changes to take effect.
Copy the snippet above into CLI.