Can you run docker on heroku? That would be the easiest because we have official image jsreport/jsreport ready.
If not, please check out this notes
https://github.com/GoogleChrome/puppeteer/blob/master/docs/troubleshooting.md#running-puppeteer-on-heroku
Also our dockerfile could be useful
https://github.com/jsreport/jsreport/blob/master/docker/default/Dockerfile