I needed to set up a Planet recently, and there appears to be very little online documentation about the process. To be fair, if you install it on Debian using apt-get, debconf will walk you through most of the setup, and it drops some examples into /usr/share/doc/planet to get you started, but here's my quick guide anyway:

How to install planetplanet on Debian

Follow these instructions at your own risk:

  1. sudo apt-get install planet
  2. Follow the prompts from the installer to fix up your basic configuration
  3. Create a virtualhost on your web server if necessary, and make the directory which the planet URL will map to
  4. Edit /etc/planet.conf to change the output_dir line to the directory you just created
  5. debconf should have set up a cron job to update the planet if you asked it to, but meanwhile you might find 'sudo planetplanet /etc/planet.conf' handy to manually update it whilst checking it's all working.