This interface layer handles the communication among Apache HBase peers.
This interface allows the peers of the HBase deployment to be aware of each other. This interface layer will set the following states, as appropriate:
-
{relation_name}.joined
A new peer in the HBase application has joined. The HBase charm should callget_nodes()
to get a list of tuples with unit ids and IP addresses for quorum members.-
When a unit joins the set of peers, the interface ensures there is no
{relation_name}.departed
state set in the conversation. -
A call to
dismiss_joined()
will remove thejoined
state in the peer conversation so this charm can react to subsequent peers joining.
-
-
{relation_name}.departed
A peer in the HBase application has departed. The HBase charm should callget_nodes()
to get a list of tuples with unit ids and IP addresses for remaining quorum members.-
When a unit leaves the set of peers, the interface ensures there is no
{relation_name}.joined
state set in the conversation. -
A call to
dismiss_departed()
will remove thedeparted
state in the peer conversation so this charm can react to subsequent peers departing.
-
For example, let's say that a peer is added to the HBase application deployment. The HBase charm should handle the new peer like this:
@when('hbase.installed', 'peer.joined')
def quorum_add(peer):
nodes = peer.get_nodes()
increase_quorum(nodes)
peer.dismiss_joined()
Similarly, when a peer departs:
@when('hbase.installed', 'peer.departed')
def quorum_remove(peer):
nodes = peer.get_nodes()
decrease_quorum(nodes)
peer.dismiss_departed()