Example reactive charm to test register_trigger

test_config_changed.py

from charms.reactive import when, when_not, set_flag
from charmhelpers.core.hookenv import log, config

from charms.reactive.flags import register_trigger

# Register a trigger so that we can respond to config.changed, even if
# it's being cleared by another handler
register_trigger(when='config.changed',
                 set_flag='trigger.config')


@when_not('test-config-changed.installed')
def install_test_config_changed():
    set_flag('test-config-changed.installed')


@when('config.changed')
def log_config_changed():
    cfg = config()
    log("#### config-changed state handled: {}".format(cfg))


@when('trigger.config')
def trigger_config_changed():
    cfg = config()
    log("#### trigger_config_changed called: {}".format(cfg))