Install rails_admin and devise. Start setting it up.

config/database.yml

@@ -17,6 +17,9 @@
 default: &default
   adapter: postgresql
   encoding: unicode
+  host: db
+  username: postgres
+  password: password
   # For details on connection pooling, see Rails configuration guide
   # https://guides.rubyonrails.org/configuring.html#database-pooling
   pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>
@@ -80,6 +83,4 @@ test:
 #
 production:
   <<: *default
-  database: myapp_production
-  username: myapp
-  password: <%= ENV['MYAPP_DATABASE_PASSWORD'] %>
+  url: <%= ENV['DATABASE_URL'] %>