The new Debian version “Trixie” has been available for upgrading from Debian “Bookworm” for several weeks now – and as a result, some of my readers have decided to update their mail server setup from my “Mail server with Dovecot, Postfix, MySQL, and Rspamd on Debian 10 Buster [v1.0] (German)”. The setup described for Debian Buster works just as well for Debian Bookworm – but Debian Trixie brings a change:
The configuration syntax has changed significantly in some respects, and old configurations from previous Dovecot versions can no longer be read. This article discusses the changes in the new version 2.4 and explains the migration using the example of the mail server instructions mentioned above. All changes take place in the file /etc/dovecot/dovecot.conf. No further changes (e.g., to the database schema or similar) are necessary.
By default LXD creates an internal network bridge called lxdbr0 which new containers are attached to (a network bridge in Linux is similar to a physical LAN switch). That way containers can talk to each other on the same network. Even the LXD host is connected to the same bridge. To make a service in a container reachable from the outside world, a proxy is used in most cases, e.g. Nginx for web services and HAProxy for any other services.
But what if you cannot or do not like to connect a service via a proxy? No problem! LXD can not only make use of a “host internal” network bridge, but any network bridge on your system. So let’s set up a network bridge that is linked to a public interface! The container’s network configuration will be similar to the one on your container host. A public IP address can be used directly.