In .env.development.local, enter values for those.
HARVEST_ACCESS_TOKEN=
HARVEST_ACCOUNT_ID=
Create a development token here.
After creating the token, choose the account you want to monitor. It's Account ID will appear under it.
HARVEST_USER_ID=
When connected to Harvest, click on your name (top-right) and then My
Profile. Your user ID will be displayed in the URL (/people/12345/edit).
If you want to keep it running while working on other Rails projects, specify a port:
PORT=3001 bin/dev
And then open http://localhost:3001.