For a rolling/mixed cluster upgrade (add new version to existing cluster
then shutdown old instances), the watches that ship by default
with monitoring may not get properly updated to the new version.
Monitoring watches can only get published if the internal state is
marked as dirty. If a node is not master, will also get marked as
clean (e.g. not dirty).
For a mixed cluster upgrade, it is possible for the new node to be
added, not as master, the internal state gets marked as clean so
that no more attempts can be made to publish the watches. This
happens on all new nodes. Once the old nodes are de-commissioned
one of the new version nodes in the cluster gets promoted to master.
However, that new master node (with out intervention like restarting
the node or removing/adding exporters) will never attempt to re-publish
since the internal state was already marked as clean.
This commit adds a cluster state listener to mark the resource dirty
when a node is promoted to master. This will allow the new resource
to be published without any intervention.
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