Comment 1 for bug 2012154

Maybe I'm missing some step when trying to reproduce the problem, but:

$ lxc launch ubuntu:focal apache2
$ lxc shell apache2
# apt update && apt install -y apache2
# a2dismod mpm_event
Module mpm_event disabled.
To activate the new configuration, you need to run:
  systemctl restart apache2
# a2enmod mpm_worker
Enabling module mpm_worker.
To activate the new configuration, you need to run:
  systemctl restart apache2
# a2enmod cgi
Enabling module cgid.
To activate the new configuration, you need to run:
  systemctl restart apache2
# systemctl restart apache2
# ls -la /run/apache2/
total 4
drwxr-xr-x 2 root root 80 Mar 21 02:28 .
drwxr-xr-x 24 root root 760 Mar 21 02:20 ..
-rw-r--r-- 1 root root 6 Mar 21 02:28 apache2.pid
srwx------ 1 www-data root 0 Mar 21 02:28 cgisock.16732
# cat > /var/www/html/foo.cgi << _EOF_
#!/usr/bin/perl
print "Content-type: text/html\n\n";
print "Hello, World.";
_EOF_
# chmod +x /var/www/html/foo.cgi
# vim /etc/apache2/sites-enabled/000-default.conf
...
        <Directory "/var/www/html">
                Options +ExecCgi
                AddHandler cgi-script .cgi
        </Directory>
...
:wq
# systemctl restart apache2

Then, in another terminal:

$ curl 10.96.142.106/foo.cgi
Hello, World.

I'm running:

# apt policy apache2
apache2:
  Installed: 2.4.41-4ubuntu3.14
  Candidate: 2.4.41-4ubuntu3.14
  Version table:
 *** 2.4.41-4ubuntu3.14 500
        500 http://archive.ubuntu.com/ubuntu focal-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu focal-security/main amd64 Packages
        100 /var/lib/dpkg/status
     2.4.41-4ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu focal/main amd64 Packages

Maybe there's something weird going with the CGI script?