Deactivate the postgres service if possible

[dmarteau]

The postgis/postgres service is enabled by default with no way to deactivate it: this is problematic when using a custom or a local database service.

Please find a way to deactivate the Postgres service and set a custom database configuration.

[rldhont]

@dmarteau is it possible in docker-compose to deactivate a service when it is needed by an other one ?

[dmarteau]

If postgis is now required for storing user database, then you may use a configuration where the postgres service run silently as backend i.e:

1. Do no publish public access to 5432
2. Don't use pgservice/pgpass, as they are also used by Qgis for SIG data.