You can add the HTTP service to runit's system-wide service supervision through the update-service(8) program:
# update-service --add dir fnord
fnord-conf arranges for tcpsvd(8) to listen for TCP connections on the address ip:80, and to run the fnord program under the uid and gid of acct, chroot'ed to webroot, for incoming connections. The name acct must not contain any special characters.
fnord-conf creates an automatically rotated log directory in dir/log/main. The logs are owned by logacct, and the corresponding svlogd(8) process runs under the uid and gid of logacct. The name logacct must not contain any special characters.