First added here, the Echo proxy is a thin Express app that proxies traffic sent to the echo-api-production.herokuapp.com URL. Version 6.7.0 of the app now sends Echo requests to echo.artsy.net, a domain we control. Older versions of the app send requests directly to Heroku, so we couldn't remove that app. Also, we couldn't deploy that app because dependencies no longer existed (see CX-386 for more info).

It's very important that this proxy app continues to run. To deploy new versions, check out the heroku-proxy-to-s3 branch locally, commit changes, push to GitHub, and deploy to Heroku:

heroku login
git push heroku +head:master # Pushes whatever commit you're on to Heroku to deploy