$Id$
There's a lot of misinformation out there regarding steps necessary to get
mysql (and optionally php or Perl) running properly inside of a chroot Apache
install (the default option in OpenBSD). Fortunately, it's not as difficult
as most people seem to think. Here's the steps I've used to install and
configure mysql to run inside a chrooted Apache (to support MediaWiki (also
in ports, requires php, also in ports)) on OpenBSD (3.9 as of this
writing; should be pretty much the same for later versions):

0) install MediaWiki (or whatever LAMP-style application you're using; if
it's in ports, it will automagically install the current php and MySQL
packages as well). The following assume OpenBSD-3.9 on i386; substitute your
current version and architecture:
$ export PKG_PATH=ftp://ftp.usa.openbsd.org/pub/OpenBSD/3.9/packages/i386/
$ ftp -a ftp.usa.openbsd.org
ftp> cd /pub/OpenBSD/3.9/packages
ftp> ls i386 pkglist
output to local-file: pkglist? [y]
ftp> bye
$ grep -i mediawiki pkglist
-r--r--r--  1 anonftp  wheel    1948308 Sep  4  2005 mediawiki-1.4.4.tgz
-r--r--r--  1 anonftp  wheel    2312650 Apr  8 09:38 mediawiki-1.5.8.tgz
$ sudo pkg_add -v mediawiki-1.5.8
  ... stuff ...

1) IF YOU DIDN'T ALREADY DO STEP 0 (ABOVE):
$ grep mysql-server pkglist
-r--r--r--  1 anonftp  wheel    4778789 Sep  4  2005 mysql-server-4.0.24p1.tgz
$ sudo pkg_add -v mysql-server-4.0.24p1
  OR, if you enjoy compiling large applications from source:
$ cd /usr/ports/databases/mysql && env SUBPACKAGE="-server" sudo make install

2) create necessary directories and symlinks
# mkdir -p /var/www/var/run/mysql/ /var/www/var/mysql
# chown _mysql:_mysql /var/www/var/run/mysql /var/www/var/mysql
# ln -s /var/www/var/run/mysql /var/run
# ln -s /var/www/var/mysql /var

3) add appropriate stuff to /etc/rc.local to start chroot mysqld on boot:
# cat >>/etc/rc.local
if [ X"${mysqld_flags}" != X"NO" -a -x /usr/local/bin/mysqld_safe ]; then
    echo -n ' mysqld'
    /usr/local/bin/mysqld_safe --datadir=/var/www/var/mysql \
    --pid-file=/var/www/var/run/mysql/mysql.pid >/dev/null 2>&1 &
fi
^D

4) create your /etc/my.cnf - socket and datadir locations are critical:
# cat >>/etc/my.cnf
[client]
# sockets go in chroot - the following are symlinks to the real sockets
socket = /var/www/var/run/mysql/mysql.sock
[mysqld]
socket = /var/www/var/run/mysql/mysql.sock
# working dir also goes in chroot
datadir = /var/www/var/mysql
# don't listen on a TCP/IP port at all - if you're going to be running a
# networked mysql, you will want to comment this next line:
skip-networking
^D

5) at this point, chroot mysqld should be starting properly on boot and be
ready for database configuration (there are plenty of resources out there on
this topic; google and mysql.com are your friends here). I recommend
testing the startup sequence outlined in /etc/rc.local to be sure that mysqld
will in fact start up as expected (reboot your machine if you're really
paranoid, but in general this is not necessary). You will of course also want
to have Apache starting on boot:

# echo httpd_flags= >>/etc/rc.conf.local

6) OPTIONAL: if you installed PHP (similar instructions for other
ports/packages), _follow_the_post-install_directions:

$ ls /var/db/pkg|grep php
php5-core-5.0.4p0/
php5-gd-5.0.4/
php5-mysql-5.0.4/
php5-pear-5.0.4/
$ pkg_info -M php5-core-5.0.4p0
Information for php5-core-5.0.4p0

Install notice:
To finish the install, enable the php5 module with:
    /usr/local/sbin/phpxs -s

To enable parsing of PHP scripts, add the following to
/var/www/conf/httpd.conf:
    
    AddType application/x-httpd-php .php

Copy the config file below into /var/www/conf/php.ini
/usr/local/share/examples/php5/php.ini-recommended

Don't forget that the default OpenBSD httpd is chrooted
into /var/www by default, so you may need to create support
directories such as /var/www/tmp for PHP to work correctly.

$ pkg_info -M php5-mysql-5.0.4
Information for php5-mysql-5.0.4

Install notice:
Enable this module in php.ini using the following command:

      /usr/local/sbin/phpxs -a mysql

----
If you're more comfortable with a GUI interface, you might also want to
install phpmyadmin (in ports, of course).

If you need Perl inside your chroot environment, I suggest reading my
document on installing Kwiki in chroot
<http://darkuncle.net/sysadmin/kwiki_in_chroot.txt> and the relevant OpenBSD
FAQ <http://www.openbsd.org/faq/faq10.html#httpdchroot>.