Colors of Noise

Apple's Calendarserver uses a file based XML backend by default. This has the disadvantage that new users must be added manually and groups can't be maintained dynamically - the calendarserver needs to be restarted.

Therefore we added a simple Name Service Switch based directory service to the Debian packages - it's best to use 1.2.dfsg-4 or newer. Using this, all users known to the system via getent passwd can have calendars and group calendars can be maintained as simple groups of users. Where your system gets it's user and group information from can be configured via /etc/nsswitch.conf e.g.:

 passwd: files ldap
 group:  files ldap

looks up users and groups in /etc/{passwd,groups} and using ldap via libnss-ldap. For more details use man nsswitch.conf. All of this can be configured dynamically without the need to restart calendarserver.

Calendarserver Configuration

To enable the NSS backend in calendarserver comment out the XML File Directory Service via <!-- ... --> in /etc/caldavd/caldavd.plist then add the NSS one. This example has all the parameters you can set:

<!-- NSS directory service -->
<key>DirectoryService</key>
<dict>
    <key>type</key>
    <string>twistedcaldav.directory.nss.NssDirectoryService</string>
<key>params</key>
<dict>
    <key>realmName</key>
    <string>Your Realm</string>

    <!-- Don't treat user ids smaller than firstValidUid as calendarserver users -->
    <key>firstValidUid</key>
    <integer>1000</integer>
    <!-- Don't treat user ids larger than lastValidUid as calendarserver users -->
    <key>lastValidUid</key>
    <integer>65533</integer>

    <!-- Groups starting with this prefix are considered calendarserver groups -->
    <key>groupPrefix</key>
    <string>caldavd-</string>

    <!-- Don't treat group ids smaller than firstValidGid as calendarserver groups -->
    <key>firstValidGid</key>
    <integer>1000</integer>
    <!-- Don't treat group ids larger than lastValidGid as calendarserver groups -->
    <key>lastValidGid</key>
    <integer>65533</integer>
    <!-- use username@mailDomain as calender user mail addresses -->
    <key>mailDomain</key>
    <string>example.com</string>
    </dict>
 </dict>

The firstValidUid and lastValidUid parameters allow you to specify which users have calendars. By default uids in the range [1000,65533] are being used. This way system users like lp, mail, news backup and nobody are excluded.

Shared calendars are represented by groups of users. The group name must start with groupPrefix to avoid collisions with system users - the default is caldavd-. The members of these groups are allowed to read/write the calendar. The firstValidGid, lastValidGid have the same meaning as the uid ones above but since you already specified a prefix you normally can simply omit them.

The mailDomain parameter can be used to specify a default mail domain. In the exmaple above a user foo ends up with mail address of foo@example.com - this information is used by some clients for free busy lists and invitations.

The values above - except for the realmName and mailDomain - are the defaults build into calendarserver, so if these suite your needs you can simply skip them:

<!-- NSS directory service -->
<key>DirectoryService</key>
<dict>
    <key>type</key>
         <string>twistedcaldav.directory.nss.NssDirectoryService</string>
    <key>params</key>
    <dict>
        <key>realmName</key>
        <string>sigxcpu.org</string>

        <key>mailDomain</key>
        <string>sigxcpu.org</string>
    </dict>
 </dict>

After changing this don't forget to restart calendarserver using /etc/init.d/calendarserver restart.

Adding users and groups

Using the configuration above all users in the range [firstValidUid,lastValidUid] readily have a calendar to access at:

http://localhost:8008/calendars/users/<user>/calendar

Adding a new user is now as easy as adduser <newuser>. The calendar get's created once the user tries to access his calendar for the first time. To add a shared calendar at:

http://localhost:8008/calendars/groups/test/calendar

simply do a addgroup caldavd-test. Then simply add users to this group: adduser test <user>. To see which users can access this particular shared calendar you can use:

getent group caldav-test

and to see all shared calendars use:

getent group | grep ^caldavd-

To see which calendars a user can access look at the output of id.

Note that {add,del}{user,group} manipluate users and groups in /etc/passwd and /etc/group only. If you're using other name service switch backends like ldap or postgresql you can use the corresponding tools instead.

Limitations

User authentication currently only works using Kerberos. This is the recommended form of authentication anyways. Let me know if you have problems setting this up.