Event 'leader-settings-changed'

Event > List of events > Lifecycle events > leader-settings-changed

Source: ops.LeaderSettingsChanged
See also: Leadership hook tools

The leader-settings-changed event is emitted when a leadership change occurs, all units that are not the new leader will receive the event. Also, this event is emitted if changes have been made to leader settings.

Contents:

Emission sequence

During startup sequence, for all non-leader units:

Scenario Example Command Resulting Events
Create unit juju deploy foo -n 2 install -> leader-settings-changed -> config-changed -> start (non-leader)

If the leader unit is rescheduled, or removed entirely. When the new leader is elected:

Scenario Example Command Resulting Events
Removal of leader juju remove-unit foo/0 (foo/0 being leader) leader-settings-changed (for all non leaders)

Since this event needs leadership changes to trigger, check out triggers for leader-elected as the same situations apply for leader-settings-changed.

Observing this event in Ops

In Ops, you can observe the event like you would any other:

self.framework.observe(
    charm.on.leader_settings_changed, 
    self._leader_settings_changed
)

With Ops, you can test for leadership with self.unit.is_leader() (ops.Unit.is_leader).

When writing unit tests with the OF harness, leadership is set with self.harness.set_leader(True) (ops.testing.Harness.set_leader).

Behind the scenes, OF uses the hook-tools is-leader, leader-set and leader-get to interact with juju regarding leadership.

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