Building on eckes' answer, adding daemon as a read-only user to any repo will render it accessible via the git:// protocol, assuming you have git-daemon configured (ships with git, may require minimal configuration).
While I haven't verified the exact process for GNU/Linux, on FreeBSD it works like so:
The following assumes you have a working git + gitolite system configured at /usr/local/git.
# echo 'git_daemon_enable="YES"' >> /etc/rc.conf
# echo 'git_daemon_directory="YES"' >> /etc/rc.conf
# echo 'git_daemon_flags="--syslog --detach --base-path=/usr/local/git"' >> /etc/rc.conf
# service git-daemon start
If you want to have all repositories automatically public, append --export-all to the git_daemon_flags above. Otherwise, add the daemon user with at least R privileges to whichever repos you want to make public, and gitolite will handle the rest.
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