I wanted to use an external Database with my heroku application. But I'm unable to edit the configuration cariables. I tried using GUI, Which says, Cannot overwrite attachment values DATABASE_URL. While I tried using CLI as well. I used the command: heroku config:addDATABASE_URL="postgresql://username:password@IP:PORT"
. However, this throws an error ... is not a heroku command.
After trying out most these answers, I came across an update in 2016, here: the database needs to be detached first, then update the variable of the DATABASE_URL.
heroku addons:attach heroku-postgresql -a <app_name> --as HEROKU_DATABASE
heroku addons:detach DATABASE -a <app_name>
heroku config:add DATABASE_URL=