You have a gitolite install on host $MASTER, and you want a mirror on $SLAVE. Here is one way to do that. $CLIENT is your workstation, that need not be the same as $MASTER or $SLAVE.
On $CLIENT, install gitolite on $SLAVE. It is ok to re-use your gitolite admin key here, but make sure you have both public and private key in .ssh, or confusion ensues. Note that when gitolite asks you to double check the "host gitolite" ssh stanza, you probably want to change hostname to $SLAVE, at least temporarily (if not, at least the checkout of the gitolite-admin repo will fail) You may want to copy .gitolite.rc from $MASTER when gitolite fires up an editor.
On $CLIENT copy the "gitolite" stanza of .ssh/config to gitolite-mirror to a stanza called e.g. gitolite-slave fix the hostname of the gitolite stanza so it points to $MASTER again.
On $MASTER, as gitolite user, make passphraseless ssh-key. Probably you should call it something like 'mirror'
Still on $MASTER. Add a stanza like the following to $gitolite_user/.ssh/config
host gitolite-mirror hostname $SLAVE identityfile ~/.ssh/mirror
ssh gitolite-mirrorat least once to test and set up any "know_hosts" file.
On $CLIENT change directory to a checkout of gitolite admin from $MASTER. Make sure it is up to date with respect origin
Edit .git/config (or, in very recent git, use
git remote seturl --push --add) so that remote origin looks like
fetch = +refs/heads/*:refs/remotes/origin/* url = gitolite:gitolite-admin pushurl = gitolite:gitolite-admin pushurl = gitolite-slave:gitolite-admin
Add a stanza
repo @all RW+ = mirror
to the bottom of your gitolite.conf Add mirror.pub to keydir.
Now overwrite the gitolite-admin repo on $SLAVE
git push -f
Note that empty repos will be created on $SLAVE for every repo on $MASTER.
The following one line post-update hook to any repos you want mirrored (see the gitolite documentation for how to automate this) You should not modify the post update hook of the gitolite-admin repo.
git push --mirror gitolite-mirror:$GL_REPO.git
Create repos as per normal in the gitolite-admin/conf/gitolite.conf. If you have set the auto post-update hook installation, then each repo will be mirrored. You should only push to $MASTER; any changes pushed to $SLAVE will be overwritten.