Docker postgres change username and password

Question

I am using the mdillon/postgis image as my containerized database. I have created a database that is owned by a user I created using the image's username and password environment variables. Now I need to changes that user's username and password.

I successfully changed the password but I could not change the username because you can change the current user's username.

I tired logging in as the postgres user but I get an error saying theres is no such user.

Any ideas?

Answer 1

Connect to the database as the firstly created user (lets call that user old_user ) and create a new superuser

CREATE USER mysuperuser WITH SUPERUSER CREATEDB CREATEROLE LOGIN PASSWORD 'mysuperuser'

Now disconnect and connect again as that suepruser. Then change old_user user's password:

ALTER USER "old_user" WITH PASSWORD 'new_password';

Then change old_user user's username:

ALTER USER old_user RENAME TO "new-user";

Finally reconnect as the new-user and delete the superuser

DROP USER mysuperuser;

You can see all users with:

SELECT usename
FROM pg_catalog.pg_user;