Baïkal (CalDAV) 0.7.0 in Gentoo

Just this past week, the new version of of Baïkal (0.7.0)—a PHP CalDAV and CardDAV server based on Sabre—was released, and one of the key changes was that support was added for more modern versions of PHP (like 7.4).

Since my personal Gentoo server is running the ~amd64 branch, I had to wait for this release in order to get my CalDAV server up and running. For the most part, installing Baïkal 0.7.0 was a straightforward process, but there were a couple of “gotchas” along the way.

The first (and most confusing) problem came after the installation/initial configuration when I tried to access my newly-created user’s calendar via the URL:

https://dav.MYDOMAIN.com/html/dav.php/calendar/MYUSERNAME/default

I knew that something was wrong when it wouldn’t even prompt me for credentials. Instead, the logs indicated the following error message:

[Tue Jun 02 14:13:05.529805 2020] [proxy_fcgi:error] [pid 32165:tid 139743908050688] [client 71.81.87.208:38910] AH01071: Got error 'PHP message: LogicException: Requested uri (/html/dav.php) is out of base uri (/s/html/dav.php/) in /var/www/domains/MYDOMAIN/dav/htdocs/vendor/sabre/http/lib/Request.php:184

I couldn’t figure out where the “/s/” was coming in before the “/html” portion, but that was certainly the cause of the error message. I filed an issue for it, and though I still don’t know the source of the problem, I was able to work around it by adding a trailing slash to the DocumentRoot for that particular vhost:

# pwd && diff -Nut dav.MYDOMAIN.conf.PRE-20200602_docroot dav.MYDOMAIN.conf
/etc/apache2/vhosts.d/includes
--- dav.MYDOMAIN.conf.PRE-20200602_docroot 2020-06-02 17:23:20.246281195 -0400 +++ dav.MYDOMAIN.conf 2020-06-02 17:20:59.892270352 -0400
@@ -1,7 +1,7 @@
- DocumentRoot "/var/www/domains/MYDOMAIN/dav/htdocs"
+ DocumentRoot "/var/www/domains/MYDOMAIN/dav/htdocs/"

After solving that strange problem, I was at least prompted for credentials when I accessed the calendar URL from above. After logging in, I ran into one more problem, though:

Class 'XMLWriter' not found

This problem was much easier to fix. I simply needed to add the ‘xmlwriter‘ USE flag to dev-lang/php (I also added ‘xmlreader‘ for good measure), emerge it again, and restart PHP-FPM. Other distributions (like CentOS) will likely need to install the ‘php-xml’ package (or something similar).

After that fix, I am happy to report that Baïkal 0.7.0 is working beautifully, and I have my calendars synced across all my devices. I personally use Thunderbird with Lightning on my computers, and a combination of DAVx⁵ with Simple Calendar Pro on my Android devices.