Xandikos is a lightweight yet complete CardDAV/CalDAV server that backs onto a Git repository.

Xandikos (Ξανδικός or Ξανθικός) takes its name from the name of the March month in the ancient Macedonian calendar, used in Macedon in the first millennium BC.

Extended documentation can be found on the home page.

Implemented standards

The following standards are implemented:

• RFC 4918/RFC 2518 (Core WebDAV) - implemented, except for LOCK operations (COPY/MOVE implemented for non-collections)
• RFC 4791 (CalDAV) - fully implemented
• RFC 6352 (CardDAV) - fully implemented
• RFC 5397 (Current Principal) - fully implemented
• RFC 3253 (Versioning Extensions) - partially implemented, only the REPORT method and {DAV:}expand-property property
• RFC 3744 (Access Control) - partially implemented
• RFC 5995 (POST to create members) - fully implemented
• RFC 5689 (Extended MKCOL) - fully implemented
• RFC 6578 (Collection Synchronization for WebDAV) - fully implemented
• RFC 7953 (Calendar Availability) - fully implemented
• RFC 6638 (CalDAV Scheduling Extensions) - fully implemented
• RFC 5546 (iCal iTIP) - implemented for REQUEST, REPLY, CANCEL
• RFC 6047 (iCalendar Message-Based Interoperability Protocol — iMIP) - implemented for REQUEST, REPLY, CANCEL; outbound delivery is off by default and configured via --imip-send
• draft-bitfire-webdav-push (WebDAV-Push) - implemented; enabled with --webdav-push. Uses Web Push (RFC 8030) with VAPID (RFC 8292) and aes128gcm message encryption (RFC 8291).

The following standards are not implemented:

• RFC 7809 (CalDAV Time Zone Extensions) - not implemented
• RFC 7529 (WebDAV Quota) - not implemented
• RFC 4709 (WebDAV Mount) - intentionally not implemented
• RFC 4324 (iCAL CAP) - not implemented

Scheduling notes

CalDAV scheduling (RFC 6638) works end-to-end when every attendee is a principal on the same Xandikos server: an organiser's PUTs and DELETEs are turned into iTIP REQUEST/CANCEL/REPLY messages, delivered into the attendees' inboxes, and auto-applied to their default calendars; attendees' RSVPs flow back into the organiser's stored event. ATTENDEE entries on the organiser's stored event are annotated with a SCHEDULE-STATUS parameter recording the delivery outcome.

Outbound iMIP for remote attendees is off by default. Set --imip-send=sendmail to pipe through a local sendmail-compatible binary, or --imip-send=smtp with --smtp-host/--smtp-port and (optionally) --smtp-encryption=starttls|ssl, --smtp-user/--smtp-password-file. --smtp-from sets the From: header; the originating organiser/attendee goes in Reply-To:. Each switch has a matching XANDIKOS_* environment variable (XANDIKOS_IMIP_SEND, XANDIKOS_SMTP_HOST, XANDIKOS_SMTP_FROM, etc.) for Docker deployments.

Inbound iMIP arrives via the xandikos import-imip subcommand, typically piped from a Dovecot Sieve rule — see examples/sieve.example and examples/xandikos-import-imip. For deployments that prefer to deliver from an MTA directly, xandikos serve --imip-listen=unix:/path/to/sock (or host:port) exposes an LMTP endpoint that accepts iMIP messages and stores them in the configured principal's schedule inbox. See examples/dovecot-lmtp.example for a server-wide setup using a Dovecot sieve_before script and a single Postfix transport entry — no per-user configuration. XANDIKOS_IMIP_LISTEN / XANDIKOS_IMIP_LISTEN_MODE / XANDIKOS_IMIP_LISTEN_GROUP environment variables work for Docker deployments. The listener uses the optional aiosmtpd dependency (pip install 'xandikos[imip-listen]'). Server-generated traffic carrying Auto-Submitted: auto-generated is skipped to avoid loops.

See DAV compliance for more detail on specification compliance.

Limitations

• Multi-user support is experimental.

Supported clients

Xandikos has been tested and works with the following CalDAV/CardDAV clients:

• Vdirsyncer
• caldavzap/carddavmate
• evolution
• DAVx5 (formerly DAVDroid)
• sogo connector for Icedove/Thunderbird
• aCALdav syncer for Android
• pycardsyncer
• akonadi
• CalDAV-Sync
• CardDAV-Sync
• Calendarsync
• Tasks
• AgendaV
• CardBook
• Apple's iOS
• homeassistant's CalDAV integration
• pimsync
• davcli
• Thunderbird

Dependencies

At the moment, Xandikos supports Python 3 (see pyproject.toml for specific version) as well as Pypy 3. It also uses Dulwich, Jinja2, icalendar, and defusedxml.

E.g. to install those dependencies on Debian:

sudo apt install python3-dulwich python3-defusedxml python3-icalendar python3-jinja2

Or to install them using pip:

python setup.py develop

Container

A Containerfile is also provided; see the comments on the top of the file for configuration instructions. The container image is regularly built and published at ghcr.io/jelmer/xandikos. For each release, a v$RELEASE tag is available - e.g. v0.2.11 for release 0.2.11. For a full list, see the Container overview page.

The container image can be configured using environment variables:

• PORT - Port to listen on (default: 8000)
• METRICS_PORT - Port for metrics endpoint (default: 8001)
• LISTEN_ADDRESS - Address to bind to (default: 0.0.0.0)
• DATA_DIR - Data directory path (default: /data)
• CURRENT_USER_PRINCIPAL - User principal path (default: /user/)
• ROUTE_PREFIX - URL route prefix (default: /)
• AUTOCREATE - Auto-create directories (true/false)
• DEFAULTS - Create default calendar/addressbook (true/false)
• DEBUG - Enable debug logging (true/false)
• DUMP_DAV_XML - Print DAV XML requests/responses (true/false)
• NO_STRICT - Enable client compatibility workarounds (true/false)
• EAGER - Pre-populate indexes at startup for faster initial queries (true/false)

See examples/docker-compose.yml and the man page for more info.

Running

Xandikos can either directly listen on a plain HTTP socket, or it can sit behind a reverse HTTP proxy.

Testing

To run a standalone (no authentication) instance of Xandikos, with a pre-created calendar and addressbook (storing data in $HOME/dav):

./bin/xandikos --defaults -d $HOME/dav

A server should now be listening on localhost:8080.

Note that Xandikos does not create any collections unless --defaults is specified. You can also either create collections from your CalDAV/CardDAV client, or by creating git repositories under the contacts or calendars directories it has created.

Production

The easiest way to run Xandikos in production is by running a reverse HTTP proxy like Apache or nginx in front of it. The xandikos script can either listen on the local host on a particular port, or it can listen on a unix domain socket.

For example init system configurations, see examples/.

Client instructions

Some clients can automatically discover the calendars and addressbook URLs from a DAV server (if they support RFC:5397). For such clients you can simply provide the base URL to Xandikos during setup.

Clients that lack such automated discovery require the direct URL to a calendar or addressbook. In this case you should provide the full URL to the calendar or addressbook; if you initialized Xandikos using the --defaults argument mentioned in the previous section, these URLs will look something like this:

http://dav.example.com/user/calendars/calendar

http://dav.example.com/user/contacts/addressbook

Contributing

Contributions to Xandikos are very welcome. If you run into bugs or have feature requests, please file issues on GitHub. If you're interested in contributing code or documentation, please read CONTRIBUTING. Issues that are good for new contributors are tagged new-contributor on GitHub.

Help

There is a #xandikos IRC channel on the OFTC IRC network, and a Xandikos mailing list.