This interface layer handles the communication between Apache HBase and its clients. The provider of this interface provides HBase services. The consumer requires the existence of a provider to function.

Charms providing the Apache HBase services provide this interface. This interface layer will set the following states, as appropriate:

• {relation_name}.joined The provider has been related to a client. At this point, the provider should broadcast availability details:

  • If HBase is running and HDFS/Zookeeper are available:
    • send_connection(master_port, regionserver_port, thrift_port, hostname, zk_connect)
  • If HBase is not running or HDFS/Zookeeper are not available:
    • clear_hbase_started()

• {relation_name}.ready HBase configuration details have been sent. The provider and client should now be able to communicate.

HBase provider example:

@when('hbase.installed')
@when('hadoop.hdfs.ready', 'zookeeper.ready', 'client.joined')
def serve_client(hdfs, zk, client):
    client.send_connection(
        get_master_port(), get_region_port(), get_thrift_port(),
        get_fqdn(), get_zk_connect(zk))

@when('client.joined')
@when_not_all('hbase.installed', 'hadoop.hdfs.ready', 'zookeeper.ready')
def stop_serving_client(client):
    client.clear_hbase_started()

Clients require this interface to connect to Apache HBase. This interface layer will set the following states, as appropriate:

• {relation_name}.joined The client charm has been related to a HBase provider. At this point, the charm waits for HBase configuration details.

• {relation_name}.ready HBase is now ready for clients. The client charm should get HBase configuration details using:

  • hbase_servers() returns a list of HBase unit dicts: {host: 'xyz', master_port: n, regionserver_port: m, thrift_port: o, zk_connect: 'zk1,zk2,zk3' }

HBase client example:

@when('hbase.joined')
@when_not('hbase.ready')
def wait_for_hbase(hbase):
    hookenv.status_set('waiting', 'Waiting for HBase to become available')


@when('hbase.ready')
@when_not('myservice.configured')
def configure(hbase):
    for unit in hbase.hbase_servers():
        add_hbase(unit['host'], unit['master_port'], unit['regionserver_port'])
    set_state('myservice.configured')

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