Deploying to fly.io

Has anyone deployed Sharetribe to fly.io and could share tips on how to make it work?
I was able to make Sharetribe work locally on my Linux machine, but running fly launch leads to an error caused by missing config/database.yml. I tried following their guide for MySQL databases, but still couldn’t make it work, with the error being:

script/entrypoint.sh: line 10: exec: --: invalid option