Finally I decided to upgrade my home server from Debian 11 Bullseye to Debian 12 Bookworm; here you can read some notes about the upgrade: Aggiornamento da Debian 11 Bullseye a 12 Bookworm.

One change that deserves a dedicated page is the upgrade from MapServer 7.6.2 shipped with Debian 11 to MapServer 8.0.1 shipped with Debian 12; in fact it happened that almost all the MapServer based applications stopped working.

In version 8 it became mandatory to have a configuration file, the default location of which is /etc/mapserver.conf. See the syntax here: https://mapserver.org/mapfile/config.html. You must declare at least the MS_MAP_PATTERN path.

In the past I used to have some CGI-Mapserver services (as native MapServer or as WMS service) where the service URL contained the full path of the mapfile, something like this:

http://www.rigacci.org/cgi-bin/mapserv?map=/usr/local/lib/mapserver/mie-strade-wms.map&

It is not a good practice to accept from the internet a parameter that is the full path to a local file. MapServer 8 requires that you declare at least a pattern that the received mapfile must obey to. Better than that, you can define several aliases (short names pointing to the mapfiles wherever they resied) and accept from the client only that aliases, disallowing the requests for a full path mapfile. I opted for the latter mode:

# MapServer 8.0 Config File
# https://mapserver.org/mapfile/config.html
CONFIG
  MAPS
    # Define the aliases for mapfile paths.
    MIE_STRADE_WMS "/usr/local/lib/mapserver/mie-strade-wms.map"
  END
  ENV
    # Disallow using full path for mapfiles (use aliases defined in CONFIG:MAPS instead).
    MS_MAP_NO_PATH "true"
    # Limit mapfile access when using full paths, this setting is never used 
    # if CONFIG:ENV:MS_MAP_NO_PATH is set.
    MS_MAP_PATTERN "^/usr/local/lib/mapserver"
  END
END

In this way the above URL will be changed into:

http://www.rigacci.org/cgi-bin/mapserv?map=MIE_STRADE_WMS&