Clusters
========

Since version 0.9.0, apt-dater has special support of cluster hosts - 
apt-dater can be configured to do not install updates on hosts part of
a cluster simultaneously.

You need to specify a symbolic name of the cluster on each cluster in
/etc/apt-dater-host.conf:

 # If this host is part of (multiple) cluster(s), you might set a
 # symbolic name. Hosts with the same cluster name won't be upgraded
 # simultaneously by apt-dater (requires apt-dater 0.9 or above).
 @CLUSTERS = qw(my-db-cluster);

The cluster name should be unique. Hosts may be part of multiple
clusters (or cluster resources).

This feature requires the lockfile-progs or procmail package. apt-dater
uses their lockfile(-create|-remove) commands to realize mutexing.
