stub42 / interface-cassandra

Cassandra interface for charms.reactive Juju charms

charms.reactive Endpoint for Cassandra clients. To use, add 'interface:cassandra' to your layer.yaml:

includes:
    - layer:basic
    - interface:cassandra

Flags

• endpoint.{endpoint_name}.joined: The relation has been joined, but may not be available.
• endpoint.{endpoint_name}.available: The Cassandra database is available.

Usage

For a relation defined in metadata.yaml named 'mydb':

from charms import reactive
from charms.reactive.flags import register_trigger
register_trigger('endpoint.mydb.changed', clear_flag='myapp.configured')

@when('endpoint.mydb.available')
@when_not('myapp.configured')
def configure():
    ep = reactive.endpoint_from_flag('endpoint.mydb.available')
    do_config(ep.details)
    ep.write_cqlshrc('root')
    reactive.set_flag('myapp.configured')

Details

The 'details' property on the endpoint provides a list-like collection (a charms.reactive.endpoint.KeyList) of CassandraDetails objects:

class CassandraDetails(object):
    relation_id = None
    username = None  # None if authentication is disabled
    password = None
    cluster_name = None
    datacenter = None
    rack = None
    native_transport_port = None
    rpc_port = None
    hosts = None  # set of IP addresses

The list may be iterated over or access by relation id:

>>> ep = charms.reactive.endpoint_from_flag('endpoint.mydb.available')
>>> any_details = ep.details[0]
>>> all_details = set(ep.details)
>>> rel_details = ep.details['db:0']