instantlinux/dovecot repository overview

⁠dovecot

The dovecot imapd daemon in a small Alpine Linux container, with postfix for local delivery and procmail for filtering.

⁠Usage

Configuration is defined as files in a volume mounted as /etc/dovecot/conf.local. Within that directory:

• Define your local settings as dovecot.conf.

• If you have an LDAP server, put its settings in passdb section of dovecot.conf. The helm chart provided here can support either Active Directory or openldap.

• (Optional, to save startup time) generate a dh.pem file for TLS:

  openssl dhparam -dsaparam -out dh.pem 4096
  

  Copy

• (Optional, to save startup time) generate self-signed server.pem and server.key files for mounting to /etc/ssl/dovecot

  wget https://raw.githubusercontent.com/dovecot/core/release-2.3.4/doc/mkcert.sh
  wget https://dovecot.org/doc/dovecot-openssl.cnf
  # (edit dovecot-openssl.cnf to suit)
  ./mkcert.sh
  

  Copy

For settings, see etc-example directory and helm⁠ / docker-compose.yml. The k8s/Makefile.vars⁠ file defines default values.

Also configure postfix as described in the postfix image.

This repo has complete instructions for building a kubernetes cluster⁠ where you can launch with helm⁠ using make after customizing overrides of values.yaml⁠ after cloning this repo:

git clone https://github.com/instantlinux/docker-tools.git
cd docker-tools/k8s
make dovecot

To provide high availability across the cluster, the helm chart here includes an optional data-sync service to keep the inbox, mail and spool directories synchronized across 2 or more worker nodes. Minor data loss can occur when the service shifts from one worker to another, so this feature isn't recommended for large production deployments (when running on a cloud provider, simply use their block storage capabilities). That said, unison-based data-sync service has been rock-solid on a bare-metal cluster for years.

Auth is the most challenging aspect of implementing dovecot. Use the following command from with the container to verify user authentication:

doveadm auth login <user>

If using openldap, turn on openldap's log setting BER to view raw packet contents as you troubleshoot login from dovecot.

⁠Variables

Need more configurability? Edit the ConfigMap defined in the helm chart.

⁠Secrets

⁠Upgrade Notes

• When upgrading to 2.3.14+, replace any references to hash: with lmdb: in your config files.

• When upgrading to 2.4+, there are a lot of gratuitous config-directive changes⁠. The Docker image doesn't contain configs but the helm chart provided here has a configmap template that contains the following changes:

⁠Contributing

If you want to make improvements to this image, see CONTRIBUTING⁠.