macOS 10.15.5 Rails 5.2.4.2 Docker 19.03.12
When deploying with Heroku in the Docker environment and then updating, execute the following command to update the contents of the Docker container.
terminal
#Log in
$ heroku container:login
#push
$ heroku container:push web
#Reflect at the end
$ heroku container:release web
This will update the contents of the Docker container deployed on Heroku!
If there is no problem when reflecting it on the browser in the Docker environment, but a migration error occurs on Heroku ...
In that case, you need to migrate separately on Heroku.
terminal
$ heroku run rails db:migrate
After that, if you reload Heroku without deploying it as it is, it will be displayed normally in the browser!