The end of Dovecot Director?

[Aki Tuomi]

To be clear, we are not removing proxying features from Dovecot either. Just the director ring feature.

Aki

> On 21/10/2022 14:14 EEST Amol Kulkarni <amolk112k at gmail.com> wrote:
> 
> 
> Nginx has an mail proxy for pop, imap, smtp.
> Can it be used instead of director ?
> 
> 
> On Fri, 21 Oct 2022 at 16:21, <hi at zakaria.website> wrote:
> > On 2022-10-21 10:51, Zhang Huangbin wrote:
> >  >> On Oct 21, 2022, at 5:23 PM, hi at zakaria.website wrote:
> >  >> 
> >  >> I was wondering if one can achieve the same implementation with 
> >  >> haproxy without dovecot director?
> >  > 
> >  > The most important part of Director is it makes sure same mail user 
> >  > always proxied to same backend IMAP server.
> >  > 
> >  > If mailbox is in Maildir format (and stored on shared storage like 
> >  > NFS), accessing it from different server may corrupt Dovecot index 
> >  > files and mailbox becomes unaccessible. Director perfectly avoids this 
> >  > issue.
> >  > 
> >  > HAProxy can proxy mail user from same client IP to same backend IMAP 
> >  > server, but not same mail user from different IPs.
> >  > 
> >  > Quote (https://doc.dovecot.org/admin_manual/director/dovecotdirector/):
> >  > 
> >  > "Director can be used by Dovecot’s IMAP/POP3/LMTP proxy to keep a 
> >  > temporary user -> mail server mapping. As long as user has simultaneous 
> >  > connections, the user is always redirected to the same server. Each 
> >  > proxy server is running its own director process, and the directors are 
> >  > communicating the state to each others. Directors are mainly useful for 
> >  > setups where all of the mail storage is seen by all servers, such as 
> >  > with NFS or a cluster filesystem."
> >  > 
> >  > ----
> >  > Zhang Huangbin, founder of:
> >  > - iRedMail: Open source email server solution: 
> >  > https://www.iredmail.org/
> >  > - Spider: Lightweight, on-premises Email Archiving Software: 
> >  > https://spiderd.io
> >  
> >  Aha makes sense, although I was not able to see how can index files be 
> >  corrupted when its if will going to be updated, its in same manner as 
> >  from different connection, e.g. opening email account from different app 
> >  clients, with different connections, does not corrupt the index files?
> >  
> >  Also, Is it the issue Director resolving as well its with maintaining 
> >  the logged in dovecot connection to same backend? Anyhow, thanks for 
> >  your valuable efforts in clearing this :)
> >  
> >  I wondered if there is any other solution to avoid corrupting index 
> >  files? Perhaps if dovecot offer database indexing as well as login 
> >  sessions, it seems that this would eliminate Director requirement, and 
> >  offer better high availability, as for now userdb/authdb is only 
> >  available per my knowledge, and using database cluster resolves the 
> >  issue with user and auth queries during simultaneous connections to a 
> >  different backends.
> >  
> >  Otherwise, it seems in large enterprise deployment with high 
> >  availability a Director implementation will be needed, hopefully we will 
> >  find an alternative solution by the time Dovecot 3 is released.
> >  
> >  I might need to get my head around building dovecot with customised 
> >  modules and review the code which was removed and return it back, if 
> >  anyone is planning to this, and well off ahead of me, please let me 
> >  know, we might be able to help one another.
> >  
> >  With thanks.
> >  
> >  Zakaria.
> >