I have no intentions of spelling everything out in detail. I am just going to indicate what worked for me. Also, my intention was merely to get Subversion working over HTTP, with basic password authentication...nothing fancy. If something I did conflicts with other blogs, I'll point it out, and explain why. My primary objective was to get a working setup - I can tweak it later. Once you know that something works, more or less, you're 90% there.
To cut to the chase, before I discovered that Ubuntu configures Apache 2.x in a non-standard way, I messed up the installation...both in /etc/apache2 and also in /usr/local/apache2. Because I'd started out by building Apache from a tarball, which I'm used to on other platforms. If you end up in the same fix, ruthlessly prune the above directories, and use Synaptic or another apt GUI to zap every package related to Apache2. Maybe even completely remove all Subversion-related packages ("Mark for complete removal" approach). Start with a clean slate, in other words.
Here's what Debian/Ubuntu does for Apache2 setup. The /etc/apache2 directory is where stuff happens. The central file is apache2.conf - this looks like the httpd.conf you are familiar with. In fact there is a /etc/apache2/httpd.conf..it starts out empty, and for the purposes of this discussion you won't need it.
apache2.conf includes, among other things, all *.conf and *.load files in /etc/apache2/mods-enabled. The former have configuration directives associated with the LoadModule directives found in the corresponding *.load files. apache2.conf also pulls in VirtualHost definitions in /etc/apache2/sites-enabled. The ports.conf file defines port numbers. The user/group for Apache2 is set in the envvars file.
If starting from scratch, just use apt-get (with sudo if necessary) to install apache2, then subversion, then libapache2-svn. If (it happened to me) you get complaints during the libapache2-svn package install of dav_svn not being found, you may discover that you have no dav_svn.conf and dav_svn.load in /etc/apache2/mods-available. A simple fix for this is just to create them yourself, as follows:
AuthName "Subversion Repository"
<LimitExcept GET PROPFIND OPTIONS REPORT>
LoadModule dav_svn_module /usr/lib/apache2/modules/mod_dav_svn.so
LoadModule authz_svn_module /usr/lib/apache2/modules/mod_authz_svn.so
Note that I've set this up for a single Subversion repository located at /var/svn/test, to be accessed with
Re-install libapache2-svn if you had to create these files for the aforementioned reason. Hopefully it will succeed.
Start or restart your server with
sudo /etc/init.d/apache2 start/restart
At this stage you ought to see your "It Works!" page at http://localhost/. If so, create your Subversion repository if necessary...in any case edit the /etc/apache2/mods-available/dav_svn.conf to reflect the actual location and the path you want to use to access it. Also, create a user with htpasswd, as in
sudo htpasswd -cm /etc/apache2/dav_svn.passwd myuser
Ensure that your repository user (chown -R) is www-data (the user as set up in envvars), and that you have appropriate permissions.
Note: I didn't even touch anything to do with virtual hosts. My successful setup is working with the 000-default virtual host...no others are defined, and I didn't edit the configuration file associated with the default host. Some blogs suggest that you must mess around with virtual hosts to get Subversion running with Apache2 on Ubuntu/Debian - that's not the case. i'm not suggesting that you shouldn't set up a virtual host to access your repo with - fill your boots. But at this point you probably just want to do Subversion things over HTTP and worry about details later.
Another note: if you do create virtual hosts, don't forget /etc/hosts.
I also didn't mess around with SSL. Once you get this far - in my experience - it's no big deal. In any case I don't need it...my repository is a private one for testing. The ones I really manage require users to be on a private network before they ever contemplate accessing a Subversion server.
One main point I'd like to make: don't trust blogs, including this one. Blog writers aren't usually trying to make your life miserable, either. But we forget that critical step (or all three of them) that really made the evolution succeed. We also forget that something often works in more than one way. Finally, we omit mention of things that are obvious to us, but not to others. Was the fact that Ubuntu configured Apache 2.x differently obvious to me? Hell no. And a lot of blog writers didn't say anything about that at all.