The end of Dovecot Director?

[William Edwards]


> Op 27 okt. 2022 om 04:25 heeft Timo Sirainen <timo at sirainen.com> het volgende geschreven:
> 
> Director never worked especially well, and for most use cases it's just unnecessarily complex. I think usually it could be replaced with:
> 
> * Database (sql/ldap/whatever) containing user -> backend table.
> * Configure Dovecot proxy to use this database as passdb.
> * For HA change dovemon to update the database if backend is down to move users elsewhere
> * When backend comes up, move users into it. Set delay_until extra field for user in passdb to 5 seconds into future and kick the user in its old backend (e.g. via doveadm HTTP API).
> 
> All this can be done with existing Dovecot. Should be much easier to build a project doing this than forking director.

This is my train of thought as well. I believe the following would suffice for most setups.

A database with:

- Current vhost count per backend server. Alternatively, count the temporary user mappings.
- Backend servers.
- Temporary user mappings between user - backend server.

This database is accessible by all Dovecot proxies in case there’s multiple.

Steps when receiving a login:

- Check if a temporary user mapping exists.
- If so, proxy to the backend server in the temporary mapping. (To do: clean up mappings.)
- If not, pick the backend server with the lowest vhost count, create a temporary mapping, then increase the vhost count of the chosen backend server.

A monitoring service up/downs backend servers. E.g. by checking the port that we proxy to for each backend server. When a backend server is set to down, kick the user to force a reconnection. (Is that how Director ‘moves’ users?)