On Tue, Oct 7, 2025 at 12:45 PM Patrick Cernko via dovecot < dovecot@dovecot.org> wrote:

Hello List,

I am proud to announce my project "wormhole". This is an extension for Dovecot 2.4.1. It allows to continue the use of the replication feature of Dovecot that was removed with the 2.4 release.

History: I started this project by forking the replication code of Dovecot 2.3.21.1 and porting it to 2.4. The first result was a patch for Dovecot 2.4.1. While working with the code, I realized that it is possible to provide the feature as a plugin / extension. In the first release of the plugin, I tried to integrate it with the existing dsync commands for doveadm. This required an API for access to the dsync commands, which I proposed to the Dovecot developers in https://github.com/dovecot/core/pull/249 . Unfortunately, my pull request was rejected, though I can understand the reasons for that. Without the required API, I had to switch to another approach: I forked the dsync code from doveadm to provide a new set of commands: "repl" and "repl-server". These commands work similar to "sync" and "dsync-server" but use additional functions required by the replication feature. This approach was released as version 0.3 of the plugin. With version 0.4 I renamed the project to wormhole. Before that it was just called dovecot-replication (see https://codeberg.org/errror/dovecot-replication). I thought that the project should have a more unique name. Currently I'm working on designing a test suite for wormhole. Doing unit tests of the components is not sufficient IMHO. The test suite should check the whole replication feature using two running dovecot instances that replicate the users' mailboxes. Having a sophisticated test suite will help in future development and bug tracking.

The code can be found on my codeberg site at: https://codeberg.org/errror/wormhole

There is also a web page on my personal homepage at: https://people.mpi-klsb.mpg.de/~pcernko/wormhole.shtml

The project is still missing documentation. For the moment, configuration is similar to the existing Dovecot 2.3 documentation.

Upgrading from 2.3: When using the included patch for Dovecot, the plugin should be 100% compatible with existing Dovecot 2.3 servers. This compatibility should allow uninterrupted upgrades of the service by replacing Dovecot on one server and then the other one. After the upgrade, the plugin can be reconfigured to work without the patch for Dovecot. Upgrading without the patch is also possible. During the upgrade (aka "while one server still runs 2.3") some aspects of the replication will not work or lack performance. Upgrading is not yet tested very well and missing documentation also. I will work on that soon.

I hope to get some feedback, pull requests or bug reports via mail or at codeberg (preferred).

Patrick Cernko <pcernko@mpi-klsb.mpg.de> +49 681 9325 5815 Joint Scientific IT and Technical Service Max-Planck-Institute für Informatik & Softwaresysteme

While I have never needed replication, this is a very welcome development and I believe the community will greatly benefit from it. Some people who were stuck on 2.3.x due to the removal of the replication feature will find this a welcome move. I thank you on their behalf :)

-- Best regards, Odhiambo WASHINGTON, Nairobi,KE +254 7 3200 0004/+254 7 2274 3223 In an Internet failure case, the #1 suspect is a constant: DNS. "Oh, the cruft.", egrep -v '^$|^.*#' ¯\_(ツ)_/¯ :-) [How to ask smart questions: http://www.catb.org/~esr/faqs/smart-questions.html]

On Tue, Oct 7, 2025 at 12:45PM Patrick Cernko via dovecot <[1]dovecot@dovecot.org> wrote:

 Hello List,

 I am proud to announce my project "wormhole". This is an extension for
 Dovecot 2.4.1.
 It allows to continue the use of the replication feature of Dovecot that
 was removed
 with the 2.4 release.

 History:
 I started this project by forking the replication code of Dovecot
 2.3.21.1 and
 porting it to 2.4. The first result was a patch for Dovecot 2.4.1.
 While working with the code, I realized that it is possible to provide
 the feature as
 a plugin / extension. In the first release of the plugin, I tried to
 integrate it
 with the existing dsync commands for doveadm. This required an API for
 access to the
 dsync commands, which I proposed to the Dovecot developers in
 [2]https://github.com/dovecot/core/pull/249 . Unfortunately, my pull
 request was
 rejected, though I can understand the reasons for that.
 Without the required API, I had to switch to another approach: I forked
 the dsync
 code from doveadm to provide a new set of commands: "repl" and
 "repl-server". These
 commands work similar to "sync" and "dsync-server" but use additional
 functions
 required by the replication feature. This approach was released as
 version 0.3 of the
 plugin.
 With version 0.4 I renamed the project to wormhole. Before that it was
 just called
 dovecot-replication (see
 [3]https://codeberg.org/errror/dovecot-replication). I thought
 that the project should have a more unique name.
 Currently I'm working on designing a test suite for wormhole. Doing unit
 tests of the
 components is not sufficient IMHO. The test suite should check the whole
 replication
 feature using two running dovecot instances that replicate the users'
 mailboxes.
 Having a sophisticated test suite will help in future development and
 bug tracking.

 The code can be found on my codeberg site at:
 [4]https://codeberg.org/errror/wormhole

 There is also a web page on my personal homepage at:
 [5]https://people.mpi-klsb.mpg.de/~pcernko/wormhole.shtml

 The project is still missing documentation. For the moment,
 configuration is similar
 to the existing Dovecot 2.3 documentation.

 Upgrading from 2.3:
 When using the included patch for Dovecot, the plugin should be 100%
 compatible with
 existing Dovecot 2.3 servers. This compatibility should allow
 uninterrupted upgrades
 of the service by replacing Dovecot on one server and then the other
 one. After the
 upgrade, the plugin can be reconfigured to work without the patch for
 Dovecot.
 Upgrading without the patch is also possible. During the upgrade (aka
 "while one
 server still runs 2.3") some aspects of the replication will not work or
 lack
 performance.
 Upgrading is not yet tested very well and missing documentation also. I
 will work on
 that soon.

 I hope to get some feedback, pull requests or bug reports via mail or at
 codeberg
 (preferred).
 --
 Patrick Cernko <[6]pcernko@mpi-klsb.mpg.de> +49 681 9325 5815
 Joint Scientific IT and Technical Service
 Max-Planck-Institute fuer Informatik & Softwaresysteme

While I have never needed replication, this is a very welcome development and I believe the community will greatly benefit from it. Some people who were stuck on 2.3.x due to the removal of the replication feature will find this a welcome move. I thank you on their behalf :)

Best regards, Odhiambo WASHINGTON, Nairobi,KE +254 7 3200 0004/+254 7 2274 3223 In an Internet failure case, the #1 suspect is a constant: DNS. "Oh, the cruft.", egrep -v '^$|^.*#' -\_(Tu)_/- :-) [How to ask smart questions: [7]http://www.catb.org/~esr/faqs/smart-questions.html]

References

Visible links

1. mailto:dovecot@dovecot.org
2. https://github.com/dovecot/core/pull/249
3. https://codeberg.org/errror/dovecot-replication
4. https://codeberg.org/errror/wormhole
5. https://people.mpi-klsb.mpg.de/~pcernko/wormhole.shtml
6. mailto:pcernko@mpi-klsb.mpg.de
7. http://www.catb.org/~esr/faqs/smart-questions.html