How do I write a rsyslog.d rule to send lines to a file?

I tried

# cat /etc/rsyslog.d/foo.sh 
:msg, contains, "foo" /var/log/foo.log
# systemctl restart rsyslog
# logger -t foo -p local0.info foo

But nothing appears in /var/log/foo.log. Even if I touch foo.log and "chmod 777" it, nothing appears. I've tried this on RHEL 8 and Ubuntu 25.04.