HTTP modules

About http module support

This assumes you already have the relevant modules enabled in your Cyrus installation, either via packages, or through a manual installation.

CalDAV, CardDAV and WebDAV all provide their functionality through an http server. Cyrus HTTP is NOT a general purpose HTTP server (such as Apache httpd). Its feature set is limited to:

  • Calendaring (CalDAV)
    • Acts as a calendar and scheduling server by using IMAP mailboxes as calendar collections and RFC 5322 messages to store iCalendar data.

    • Allows non-CalDAV/remote calendar clients to query freebusy information of Cyrus CalDAV users via freebusy URLs.

    • Allows scheduling transactions between separate calendaring and scheduling systems via the iSchedule protocol (currently only used within a Cyrus Murder).

    • Acts as a Time Zone Distribution Service by serving iCalendar (VTIMEZONE) data to client systems.

  • Contacts (CardDAV)
    • Acts as a contacts server by using IMAP mailboxes as addressbook collections and RFC 5322 messages to store vCard data.

  • File Storage (WebDAV)
    • Acts as a remote storage server server by using IMAP mailboxes as collections and RFC 5322 message to store files.

  • JMAP support
    • Allows synchronization of mail clients via the JSON Mail Access Protocol (JMAP).

  • Other (RSS, static content)
    • Serves static content (such as the RSS feed list template and the CalDAV/CardDAV web GUIs).

    • Serves IMAP mailboxes as RSS feeds.

HTTPD Configuration

General configuration

The Cyrus httpd service is configured using options in imapd.conf(5).

The support for RSS, CalDAV, and CardDAV is divided into separate modules which run as part of the Cyrus httpd service. Selection of which module(s) are enabled is done by setting the httpmodules option. By default, no modules are enabled.

Cyrus httpd also can serve static content, the location of which is set by the httpdocroot option. Any content contained in the specified directory (including sub-directories) will be served as static content only. Cyrus httpd does NOT have the ability to execute any server-side scripts.


As with other Cyrus services, the Cyrus httpd service uses Cyrus SASL to perform its authentication.

Similar to plaintext login commands supported by the other Cyrus services (IMAP LOGIN, POP3 USER/PASS), the Cyrus httpd service determines whether to advertise the HTTP Basic authentication scheme based on the allowplaintext option and whether the client has connected over a TLS protected connection (HTTPS). BASIC authentication does not depend on a Cyrus SASL plugin.

The advertisement of the other HTTP authentication schemes is controlled by the SASL mech_list option option. For Cyrus httpd the DIGEST-MD5, GSS-SPNEGO, NTLM, SCRAM-SHA-1, and SCRAM-SHA-256 values enable support for the Digest, Negotiate (Kerberos only), NTLM, SCRAM-SHA-1, and SCRAM-SHA-256 authentication schemes respectively, provided that the plugins are installed on the server.

For end users

Some information must be passed on to your end users so that they know how to configure their clients in order to access their data on Cyrus. The list below needs to be customized to your specific hostnames.

  • CalDAV
    • Many clients find calendars automatically if you provide the correct server, username and password.

    • Otherwise, use the direct URL: https://<servername>/dav/calendars/user/<userid>/<calendar>/

  • Freebusy
    • https://<servername>/freebusy/user/<userid> - considers all CalDAV collections of the user

    • https://<servername>/freebusy/user/<userid>/<collection-name> - considers a single CalDAV collection

    • Query parameters can be added to the URL per Section 4 of Freebusy Read URL.

  • CardDAV
    • Many clients find addressbooks automatically if you provide the correct server, username and password.

    • Otherwise, use the direct URL:https://<servername>/dav/addressbooks/<userid>/<addressbook>

    • The address book(s) are automatically filtered based on the username and password supplied.

  • WebDAV
    • https://<servername>/dav/drive/user/<userid>

  • RSS
    • https://<servername>/rss/

    • Serves up all mailboxes (read-only) that the authenticated user has access to.