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#!/usr/bin/env python3
import os
import sys
sys.path.insert(0, os.path.join(os.environ['CHARM_DIR'], 'lib'))
from hookenv import relation_set, relation_get, log, relation_id
import random
def generateWorkerKey():
"""Return a random key of length 4,
which will be passed as new workers join."""
return ''.join(random.choice('0123456789ABCDEF') for i in range(4))
def master_application_relation_joined():
[name]-relation-joined is run only when that remote unit is first observed by the unit.
It should be used to relation-set any local unit settings that can be determined using no more than the name of the
joining unit and the remote private-address setting, which is always available when the relation is created and is
by convention not deleted.
You should not depend upon any other relation settings in the -joined hook because they’re not guaranteed to be
present; if you need more information you should wait for a -changed hook that presents the right information.
log(" ========= hook: master-application-relation-joined ========")
# Generate a worker-key
workerKey = generateWorkerKey()
# Get the remote unit name so that we can use that for a composite key.
remoteUnitName = os.environ.get('JUJU_REMOTE_UNIT', None) # remote_unit()
# Get the worker remote unit private-address for logging
workerAddr = relation_get('private-address', unit=remoteUnitName)
log(f"Joined with WORKER at private-address: {workerAddr}")
# Assemble the relation data.
relation_data = { f"{remoteUnitName}-worker-key": workerKey }
# Set the relation data on the relation.
relation_set(relation_id(), relation_settings=relation_data )
if __name__ == "__main__":