Heroku PostgreSQL scheme fix

SQLAlchemy doesn't support postgres:// scheme for database connections.

https://help.heroku.com/ZKNTJQSK/why-is-sqlalchemy-1-4-x-not-connecting-to-heroku-postgres

You can’t change the heroku config; it’s set by the addon. But, you can modify the ENV var in-dyno before starting your process.

$ env DATABASE_URL=postgres://credential \
  bin/pg-env-fix --attachment DATABASE \
  printenv DATABASE_URL

[PGENVFIX] modifying DATABASE_URL
postgresql://credential

The innards

Write a script, call it something like launch.py (or launch.sh or whatever — depending on your language. I’m sure you could do this with sed in bash). TBH I don’t care what you call it 😄.

This scripts job is to:

• Read in the DATABASE_URL env var.
• Modify it, replacing postgres with postgreql
• Re-export it, overwriting the original.
• Launch a command using all the rest of the input parameters.

Then you can modify your Procfile so it does something like this:

web: ./launch bundle exec puma