Notes for Packagers

Sample configuration files

There are several samples of cyrus.conf(5) and imapd.conf(5) located in the doc/examples directory of the distribution tarball. Please install these to your preferred documentation directory (i.e. /usr/share/doc/cyrus-imapd) as a reference for your users.

Predefined configurations

The configuration file for master: cyrus.conf

When installing a predefined cyrus.conf(5) for your users, please pay attention to new features and how these may impact users. For example, for some time now, Cyrus has supported placing several standard DB files in temporary, or ephemeral, storage, such as memory backed filesystems like tmpfs (see below). This both boosts efficiency and ensures DB consistency in event of a crash or other system disruptive events. But, in light of this, actions which depend on the existence of these database files should not be placed in the START section of cyrus.conf(5).

Section Purpose

A new section, DAEMON, was added to cyrus.conf(5) in version 2.5. Please consult cyrus.conf(5) for details. Please refer to the notes in Section Descriptions pertaining to the distinctions between START, EVENTS and DAEMON sections.

In brief, the sorts of things which should go into the different sections are:

  • START
    • Programs which should be spawned by master(8) which are expected to cleanup after themselves
    • do not rely on any ephemeral files or resources
    • master(8) will not start until all entries in START have either ended or backgrounded themselves.
  • SERVICES
    • Service daemons managed by master(8)
    • master(8) will listen on ports or sockets as specified and dispatch new child processes as needed, destroy old or stale processes, etc.
  • EVENTS
    • Periodic processes which will be started by master(8) as specified.
  • DAEMON
    • Programs which should be spawned by master(8) which it should shut down and clean up after.

The configuration file for the various programs: imapd.conf

The sample imapd.conf(5) files must be adapted for use from site to site. Here, therefore, we’ll attempt to point you towards some reasonable settings which take advantage of recent improvements and features, and may help guide you and your users to a better performing Cyrus installation.

Ephemeral files and temporary filesystems

In addition to Unix domain sockets and lock files, several databases used by Cyrus programs may be located in temporary filesystems, such as those backed by RAM (i.e. tmpfs, md, etc.). Here’s a list of such files. In this example, the filesystem /run is on tmpfs:

proc_path: /run/cyrus/proc
mboxname_lockpath: /run/cyrus/lock
duplicate_db_path: /run/cyrus/deliver.db
statuscache_db_path: /run/cyrus/statuscache.db
ptscache_db_path: /run/cyrus/ptscache.db
tls_sessions_db_path: /run/cyrus/tls_sessions.db
lmtpsocket: /run/cyrus/socket/lmtp
idlesocket: /run/cyrus/socket/idle
notifysocket: /run/cyrus/socket/notify

Note

Any process which depends on these files already existing should not be placed in the START section of cyrus.conf(5), or the server will not start as expected.

New default settings

With the introduction of version 3.0, the defaults for some settings have changed. Please consult Upgrading to 3.0 for details.

New features

There are several features either new to version 3.0, or newly improved. Some of these may be features which previously were not considered ripe for packaging, but merit new consideration.

Please see the release notes Major changes since the 2.5.x series for more details and other recent changes.

  • Conversations
    • Server-side threading with reduced protocol chatter for mobile or other high-latency clients.
    • Required for JMAP support.
    • See the conversations options in imapd.conf(5)
  • JMAP
    • JSON Mail Access Protocol
    • Follow-on successor to IMAP (“J comes after I”) with a special focus on mobile and other clients with high-latency or unreliable connectivity.
    • Includes Calendaring, Contacts, Conversations, message delivery.
    • See httpmodules in imapd.conf(5)
  • Xapian
    • Higher quality full-text search support.
    • Required for JMAP support.
    • See the search_engine option in imapd.conf(5) and doc/README.xapian in the source distribution.
  • Archive partitions
    • Automatically migrate messages from posh, fast storage (think SSD) to cheap, slow storage (spinning rust).
    • Requires addition of an archive partition for each data partition.
    • See archive_* options in imapd.conf(5)
  • Backup
    • Replication-based backup to dedicated instance with efficient, compact scheme.
    • See Cyrus Backups

Please consider enabling these features in the imapd.conf(5) you ship in your packages.

Services in /etc/services

Listing named services through /etc/services aids in cross-system consistency and cross-platform interoperability. Furthermore, it enables administrators and users to refer to the service by name (for example in /etc/cyrus.conf, ‘listen=mupdate’ can be specified instead of ‘listen=3905’).

Some of the services Cyrus IMAP would like to see available through /etc/services have not been assigned an IANA port number, and few have configuration options.

The Cyrus IMAP server provides service interfaces via either TCP/IP ports or Unix domain sockets. For the former, Cyrus requires that there are proper entries in the host’s /etc/services file. The following are required for any host using the listed services:

pop3      110/tcp  # Post Office Protocol v3
nntp      119/tcp  # Network News Transport Protocol
imap      143/tcp  # Internet Mail Access Protocol rev4
imsp      406/tcp  # Internet Message Support Protocol (deprecated)
nntps     563/tcp  # NNTP over TLS
imaps     993/tcp  # IMAP over TLS
pop3s     995/tcp  # POP3 over TLS
kpop      1109/tcp # Kerberized Post Office Protocol
lmtp      2003/tcp # Lightweight Mail Transport Protocol service
smmap     2004/tcp # Cyrus smmapd (quota check) service
csync     2005/tcp # Cyrus replication service
mupdate   3905/tcp # Cyrus mupdate service
sieve     4190/tcp # timsieved Sieve Mail Filtering Language service

Make sure that these lines are present or add them if they are missing.