Dovecot Pro Palomar Architecture

⚠️ TODO

Right now, this intro describes the cluster service, but not Palomar in general.

We should add documentation to this page that describes:

• sites
• users
• routing
• health checking
• administration
• statistics
• balancing
• ???

The Dovecot Pro Palomar Architecture in v3.x replaces the director component in older Dovecot versions with a new cluster service.

The cluster service provides:

• Load balancer between Dovecot Proxies and Backends
• User-stickiness to backends
• High availability for backends and other sites
• Load redistribution / user moving
• Multi-site support

The architecture aims to serve each user via a single backend at a time. This allows caching to work efficiently. When using object storage and multiple sites, it's possible that the user is served simultaneously by multiple sites when the sites' networks don't see each other (split brain). The obox format handles this by eventually merging the changes and moving the user handling back to a single site soon after the split brain is over.

Overview

Components

• Dovecot Proxy
• Dovecot Backend
• Cluster Controller
• Palomar GeoDB
• Storage
• OX Abuse Shield

Sites

In Palomar, a site is a collection of servers intended to operate and be maintained together by a single Cluster Controller.

A single Palomar installation can contain multiple sites.

Multi-Site

⚠️ TODO

Shared Infrastructure

⚠️ TODO

Authentication

⚠️ TODO

Storage

⚠️ TODO

GeoDB?

⚠️ TODO

Other

⚠️ TODO

Backend Monitoring

For health-checking purposes, Palomar uses "test users" to perform a variety of actions on the Backends. These test users are using the same endpoints as users, so this more accurately measures an end user's experience rather than relying on abstract metrics and statistics.

Information on how to configure these test users can be found at Palomar Monitoring Users.

Features

Automatic Load Rebalancing

See Palomar Load Rebalancing.

Logging

See Palomar Logging.