The autojoin directive enables nodes to join automatically just by communicating with the cluster, hence not requiring node directives in the ha.cf file. Since our communication is normally strongly authenticated, only nodes which know the cluster key can join (automatically or otherwise).
The general syntax of the autojoin directive is:
All legal autojoin directives are shown below:
autojoin none autojoin other autojoin any
The values you can give for the autojoin directive have the following meanings:
none: disables automatic joining.
other: allows nodes other than ourself who are not listed in ha.cf to join automatically. In other words, our node has to be listed in ha.cf, but other nodes do not.
any: allows any node to join automatically without being listed in ha.cf, even the current node.
Note that the set of nodes currently considered part of the cluster is kept in the hostcache file.