Ecto.reset inside docker container does not work

Question

I am building a RESTful API with Phoenix and PostgreSQL and run the Phoenix app and the database in separate docker containers using docker-compose. If I attach a shell to the Phoenix container and type mix ecto.reset to reset the database, I get the following error:

** (Mix) The database for Home.Repo couldn't be dropped: ERROR 55006 (object_in_use): 
database "home" is being accessed by other users

There are 10 other sessions using the database.

I already tried this:

REVOKE CONNECT ON DATABASE dbname FROM PUBLIC, username;

SELECT 
    pg_terminate_backend(pid) 
FROM 
    pg_stat_activity 
WHERE 
    pid <> pg_backend_pid()
    AND datname = 'database_name';

What am I doing wrong?

Answer 1

You shouldn't stop only the cowboy webserver in this case, as it requires many phoenix dependencies to be up again, and most likely there will be a Supervision tree to restore the process if you find it and kill it yourself. So, as mentioned before, you should stop your whole phoenix server with Application.stop(:your_app) inside iex, and then do ecto.reset and start it again.

Although, you shouldn't need to use ecto reset within a running application, ecto.reset does the following: "ecto.drop", "ecto.create", "ecto.migrate". You should check if the drop is really necessary, as that is what's impossible to do in a running application that relies on database.

If you're resetting for testing purposes, for example, then you should also check Ecto.Sandbox, that sets up a copy database for each test: https://hexdocs.pm/ecto/Ecto.Adapters.SQL.Sandbox.html#content